U.S. GEOLOGICAL SURVEY CIRCULAR 1054 

A User's Manual for a 

Method of Map Scanning and 

Digital Editing for 

Thematic Map Production and 

Data-Base Construction 
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A User's Manual for a 

Method of Map Scanning and 

Digital Editing for 

Thematic Map Production and 

Data-Base Construction 

By DAVID R. SOLLER, WILL R. STETTNER, KENNETH j. 

LANFEAR, and DOUGLAS S. AITKEN 

U.S. GEOLOGICAL SURVEY CIRCULAR 1054 
U.S. DEPARTMENT OF THE INTERIOR 

MANUEL LUJAN, Jr., Secretary 

U.S. GEOLOGICAL SURVEY 

Dallas L. Peck, Director 

Any use of trade, product, or firm names in this publication is for descriptive 

purposes only and does not imply endorsement by the U.S. Government 

UNITED STATES GOVERNMENT PRINTING OFFICE: 1990 

Free on application to the 

Books and Open-File Reports Section 

U.S. Geological Survey 

Federal Center, Box 25425 

Denver, CO 80225 

Library of Congress Cataloging in Publication Data 

A user's manual for a method of map scanning and digital editing for thematic map production and data-base construction I by David R. Soller ... 

[et al.]. 

p. em. - (U.S. Geological Survey circular; 1054) 

Includes bibliographical references (p. 

Supt. of Docs. no.: 119.412:1054 

1. Digital mapping. 2. Scanning systems. I. Soller, David Rugh. II. Series. 

GA139.U8 1990 

526-dc20 90-13921 

CIP 
CONTENTS 

Abstract 1 

Introduction 1 

Acknowledgments 2 

Background Discussion 2 

Justifications for a Digital Approach to Map Production 2 

The Test Map 2 

Line Accuracy and Scanner Resolution 3 

Our Method 3 

About the User's Manual Format and Syntax 5 

A. Preparing for Map Scanning 5 

B. Map Scanning 6 

B-1. Getting Started 6 

B-2. Setting the Scanning Parameters 6 

B-3. Setting Other Parameters 8 

B-4. Initiating the Scan 9 

B-5. Background Scanning 9 

C. Preliminary Editing Using TekniCAD 10 

C-1. Getting Started 10 

C-2. Displaying the Scanned Image 10 

C-3. Deleting Lines 11 

C-4. Repairing Line Breaks 12 

C-5. Repositioning Points and Line Segments 12 

C-6. Tracing Linework 13 

C-7. Saving Edited Linework and Exiting TekniCAD 13 

C-8. Saving Files to Backup Tape 13 

C-9. Deciding Whether to Edit in TekniCAD or ARC/INFO 14 

D. Transferring the Map Data to the ARC/INFO Environment 14 

E. Preparing ARC/INFO Coverages for Editing 15 

E-1. Initiating ARC/INFO and Describing the Display Device 15 

E-2. Copying Coverages 15 

E-3. Adding Latitude-Longitude Tic Marks to Each Coverage 16 

E-4. Converting Tic Coordinates from Scanner Units to Latitude and Longitude 17 

E-5. Selecting a Map Projection and Projecting the Empty Coverage 18 

E-6. Transforming Coverages to Map Projection Coordinates 18 

E-7. Delineating the Boundaries of Maps Lacking Neatlines 19 

E-8. Checking and Adjusting Registration 21 

F. Editing the Coverages in ARCEDIT 22 

F-1. Setting Up an ARCEDIT Session 22 

F-2. Cleaning Up the Linework 23 

F-3. Ordering the ID Numbers in the Attribute Tables 23 

F-4. Adding Polygon Information to Each Coverage 24 

F-5. Assigning Item Values to Arcs on the basis of Polygon Item 

Values 25 

F-6. Checking for Tagging Errors 26 

Contents Ill 
IV Contents 

Our Method-Continued 

F. Editing the Coverages in ARCEDIT -Continued 

F-7. Combining Coverages and Eliminating Sliver Polygons 27 

F-8. Unsplitting Arcs 29 

G. Generating Color Separates for Map Printing 30 

G-1. Converting Map Data from ARC/INFO to Scitex Format 30 

G-2. Transferring the Scitex-Format Files from ARC/INFO to Scitex 32 

G-3. Scitex Processing to Produce Color Separates 32 

G-4. Converting ARC/INFO Coverages to DLG Format and Outputting to 

Tape 34 

References Cited 35 

Appendix, Description of the Prototype Method 36 

FIGURE 

1. Diagram showing steps in digital production of maps by our method 4 

METRIC CONVERSION FACTORS 

Multiply By 

inch (in.) 25.4 

foot (ft) 0.3048 

millimeter 0.03937 

meter 3.281 

To obtain 

millimeter (mm) 

meter (m) 

inch 

foot 
A User's Manual for a Method of Map Scanning and 

Digital Editing for Thematic Map Production and 

Data-Base Construction 

By David R. Soller, Will R. Stettner, Kenneth j. Lanfear, and Douglas S. Aitken 

Abstract 

This report describes a method of scanning manuscript maps, manipulating the digital map data, and outputting the data as color separates for map printing. The 

edited digital data can be used to build a data base for 

analysis in a geographic information system (GIS). This 

new combination of digital techniques was applied to an 

unpublished regional geologic map. We selected a Tektronix autovectorizing scanner, ARC/INFO GIS software, 

and a Scitex digital plotter to prepare the map separates 

for printing. 

This method is intended to enhance existing digital 

map production capabilities. It is appropriate for research 

projects that need a digital map data base for analysis but 

cannot justify the time and expense of contractual services 

for map scanning, manual digitizing, or digital map editing. It is not necessarily the best or only approach to 

digital map production or creation of digital data bases; 

rather, it is an interim method, parts of which will soon 

become obsolete. Meanwhile, this method could be 

adopted, in part or in total, by others. 

This report is organized as a user's manual, providing 

detailed step-by-step descriptions of the method. It is 

limited in scope and cannot address all the topics and user 

skills that are required. Therefore, it is intended for users 

having at least a rudimentary understanding of the various 

hardware and software systems involved. 

INTRODUCTION 

Traditionally, maps have been created, revised, and 

reinterpreted by hand on paper or on scale-stable base 

materials and then have been prepared for printing. For 

many maps and research projects, traditional cartographic 

techniques are still preferred. However, for an increasing 

number of map projects, digital computer technologies offer 

an approach to map production that holds certain advantages, such as the compilation of a digital data base that can 

Manuscript approved for publication, July 19, 1990. 

be used for scientific analysis. In recent years, computerization of geographically referenced data has increased, and 

sophisticated geographic information system (GIS) software 

has been written to store and manipulate these data. This 

technology is continually improving and changing. In the 

past, it has not been feasible for many thematic maps, 

which have unique formats. Rather, computer techniques 

were the domain of large projects that required the handling 

of many data and the standardization of the format of map 

data. Such projects, through this standardization, achieved 

cost-efficient map production. 

In the past few years, the growing interest in GIS and 

GIS data bases, supported at the U.S. Geological Survey 

(USGS) by its regional GIS research laboratories, has 

spurred research into the applicability of computer techniques to a wider range of unpublished thematic maps. One 

such thematic map was used to develop the combination of 

methods discussed in this report. That map depicts the 

three-dimensional framework of glacial deposits covering 

25 percent of the continental United States and is referred to 

in this report as the "test map" and the "Quaternary 

sediments map"; it will be published in four sheets (Soller, 

in press a-d). It was originally destined for preparation by 

conventional cartographic techniques. Instead, a digital, 

computer-based approach was selected for two reasons. 

First, the map is large and complex, and it was judged that 

digital techniques would yield greater legibility than would 

conventional preparation of color separates (separate negatives for each color that will be used to produce the map). 

Second, the map data were needed in a digital format for 

GIS-based research. 

Initially, this map project relied on a prototype 

method that used existing digital production capabilities at 

the USGS. The method was developed by C.J. Cialek 

(USGS, written commun., 1987) and was discussed by Utz 

and others (1988). The prototype method had many tasks 

and required numerous transfers of the map data between 

different computer systems. Much time was needed for 

reformatting and computer processing, and operator costs 

Introduction 
were high. Because of more recently developed hardware 

and software, parts of that method are now obsolete. 

However, the prototype method is briefly described in this 

report (see appendix) to provide a historical perspective on 

the evolution of digital map production. 

For the Quaternary sediments map, we wanted a more 

cost-effective method that could make use of new hardware 

and software. We also desired more control over the 

scheduling and performance of data processing and editing. 

In developing the new method, two objectives were 

addressed: first, an informal, readily accessible means for 

individual scientists to acquire digital data from unpublished maps in order to conduct digitally based research, 

and, second, more efficient methods of manipulating digital 

manuscript maps and of converting manuscript maps into 

color separates for printing. 

For our method, we chose to scan the Quaternary 

sediments map on a Tektronix autovectorizing scanner, a 

relatively low cost device that captures linework at acceptable levels of resolution. Manual digitizing was not considered a viable option because of the large format of the 

Quaternary sediments map and the need for rapid production with high levels of accuracy. We chose to use 

ARC/INFO GIS software (a product of ESRI (Environmental Systems Research Institute), Inc., Redlands, Calif.) for 

data manipulation because it fulfills our requirements and 

because it is commonly used at the USGS. Scitex equipment was used to process and plot the color separates 

because it has a high level of resolution, produces highquality printing screens, and can plot complete negatives for 

large-format maps (having maximum dimensions of about 

40X73 in.). All work except Scitex processing can be done 

by scientists with equipment open to general use in the GIS 

research laboratories of the USGS. 

Like the prototype method, ours is an interim 

method, parts of which will soon become obsolete. In the 

rapidly changing field of digital mapping and cartography, 

the evolution of methods and equipment is both commonplace and welcome. In time, our method's primary value 

will be to document one small part of that evolution. 

Acknowledgments 

The authors extend their appreciation to Russell H. 

Campbell, David E. Catts, Cynthia M. Crampsey, Todd T. 

Fitzgibbon, Thomas L. Johnson, and David W. Stewart (all 

USGS) for reviewing the manuscript and the method and to 

Elizabeth E. Good (USGS) for a careful and thoughtful 

editorial review. The authors acknowledge the work of 

Christopher J. Cialek (USGS) in developing the prototype 

method that enabled digital processing of the Quaternary 

sediments map to begin. Thanks also to Brian S. Bennett 

(USGS), for performing the ARCSCITEX conversion, and 

to Carl L. Rich (USGS), for providing a tape-writing 

program. This report was supported mostly by Innovative 

Projects funding from the GIS Policy Task Force of the 

USGS; special thanks to Nick VanDriel for his encouragement. Additional salary support was provided by the 

National Geologic Mapping Program and the National 

Water Summary Program. 

BACKGROUND DISCUSSION 

Justifications for a Digital Approach to Map 

Production 

Digital techniques for map production are continually 

being created and refined by many individuals and organizations. In the past, production costs at the USGS for 

digitally produced thematic maps have been significantly 

greater than those for conventionally prepared maps. However, these costs cannot be fairly compared because digital 

techniques have yet to be standardized; each digitally 

produced thematic map has, in essence, been a methodsresearch project. The need to print the Quaternary sediments map has resulted in two new production methods: the 

prototype method and the method described in this report. 

Because the Quaternary sediments map has not yet been 

printed, publication costs (including costs for all phases of 

the digital procedure) are not known. However, costs for 

map scanning and assigning attributes to map features 

according to our method are significantly less than those 

costs for the prototype method. As existing methods are 

refined and new ones are developed, digital map production 

costs should continue to decline. 

For many thematic maps, the most significant reason 

to produce a map by digital techniques is that a digital data 

base is created by the process. This data base can have 

many uses whose importance may overshadow that of the 

printed map. Unlike the printed map, the data base is 

dynamic. It can be updated and reinterpreted, and a revised 

map or a derivative map can be published with relatively 

minor effort or expense. The data base can be analyzed in 

conjunction with other data bases to provide information in 

support of scientific research or interdisciplinary topics, 

such as land-use and environmental management. 

Another reason for printing maps from digital data is 

that the inherent precision of digitally produced color 

separates permits a greater level of map detail than that 

possible by conventional techniques: more complex map 

units and patterns are possible, and the author can have 

greater control over map colors and appearance. Digital 

map production can, therefore, encourage the design of new 

types of maps incorporating different and more effective 

approaches to data presentation. 

The Test Map 

The test map used to develop both the prototype 

method and our method is a 1:1,000,000-scale manuscript 

2 A User's Manual for a Method of Map Scanning and Digital Editing 
map showing Quaternary deposits for the glaciated area of 

the United States east of the Rocky Mountains (Soller, in 

press a-d). Parts of southern Ontario, areas beneath the 

Great Lakes, and parts of the submerged eastern seaboard 

are also shown on the map. The map shows the character of 

sediments exposed at the surface, the thickness of Quaternary sediments, and where possible, certain buried Quaternary units. This map is very large, and it requires the use of 

scratch boundaries (lines that are not intended for plotting 

but that are used to separate areas filled by different colors) 

and blocked-out areas (areas where a color is blocked out 

beneath pattern elements to allow another color to print). 

The use of scratch boundaries and blocked-out areas 

requires precise registration during printing, and it was 

determined that conventional map production methods 

would not give satisfactory results for a map of this size and 

detail. 

The Quaternary sediments map spans four map sheets 

and has an overall size of roughly 4X 12ft. The largest sheet 

is approximately 42X55 in. The topographic base map on 

each sheet is composed of a hand-mosaicked group of 

4 ox 6° quadrangles from the International Map of the World 

Series or Army Map Service 1:1,000,000-scale maps; all 

these maps are available from the USGS. Because each 

quadrangle has unique map projection parameters, and 

because these map sheets include as much as 12° of latitude 

and longitude, a precise mosaic is impossible. In order to 

preserve the registration of the geologic information to the 

base map without sacrificing the spatial integrity of the 

digital data base, entire map sheets were not scanned. 

Rather, the four layers of geologic information shown on 

the map (character of sediments exposed at the surface, 

thickness of Quaternary sediments, buried units and surface 

veneer units, and miscellaneous point and line information) 

were scanned separately for each 4°X6° quadrangle, and the 

scanned data were recombined on the base map. 

We designed and tested our method on the smallest of 

the four map sheets (Soller, in press d). This sheet is 

composed of four 1:1,000,000-scale quadrangles, shows 

the continentally glaciated parts of Montana and western 

North Dakota, and has a physical size of about 12X32 in. 

Because the sheet contains mapped areas on small parts of 

four adjoining quadrangles, we decided to scan the entire 

sheet in one piece, and we selected map projection parameters that were a compromise for the four quadrangles. We 

required 59 hours to scan, edit, and prepare the map for 

Scitex processing (steps 1-13 discussed below). 

Line Accuracy and Scanner Resolution 

Planning a new method to supersede the prototype 

required adoption of new equipment as well as new techniques. The most significant change in hardware was the 

use of a Tektronix scanner that is accessible to general 

users. It is a relatively low cost device, and it has lower 

resolution than the Scitex scanner. The Tektronix scanner 

operates at a resolution of 0.0833 mm (0.00328 in.). In 

Scitex pixels, this translates to a resolution of 12 pixels per 

millimeter, which, in Scitex terminology, is denoted as 

RES 12. Although the Scitex can operate from RES4 to 

RES47, a resolution of RES17 (or sometimes RES34) is 

commonly used for thematic maps. 

In order to compare output from the two scanners, we 

performed a Scitex RES 17 scan of the map area scanned by 

the Tektronix. Because the Tektronix-scanned data had 

been edited on the Tektronix workstation and in ARC/INFO 

and had been projected, transformed, and combined with 

other map data in ARC/INFO, we were not able to directly 

compare the raw, scanned data. The Tektronix-scanned 

data, which were manipulated as required to create the fully 

edited data base, could not be expected to preserve the line 

positions exactly as scanned. Nevertheless, we compared 

Scitex-generated film plots of both the Scitex and Tektronix 

scans by visual inspection. This comparison indicated that 

the scribed lines (on the scan copy) were as faithfully 

reproduced by the Tektronix scanner as by the Scitex 

scanner. 

Despite the results from our visual comparison of the 

scans, the lower resolution of the Tektronix may concern 

some users. The lower resolution may seem to indicate that 

the Tektronix scanner will produce digital lines whose 

positional accuracy is unacceptably low. However, for most 

thematic maps, the resolution of the scanner is high compared to the precision with which a line can be placed on the 

map by the author, in part because lines on thematic maps 

are interpretive. As a geologic map is being constructed, the 

author must consider a variety of information from a 

number of sources to determine where lines will be drawn. 

Because the geologist must postulate and rely on stratigraphic, temporal, and process-oriented models to explain 

the fragments of physical information available, geologic 

contact lines are interpretive features that have a certain 

amount of positional uncertainty. This uncertainty may or 

may not be constant and definable for the entire map. Lines 

are especially interpretive on maps of smaller scale, such as 

the Quaternary sediments map. In addition to these inherent 

uncertainties in line position, small changes in line location 

are introduced by conventional scribing or digital plotting 

for map printing. On the basis of these considerations, we 

think that the lower resolution of the Tektronix scanner is 

not significant for thematic maps. 

OUR METHOD 

Our method is based on three hardware and software 

systems: the Tektronix 4991 autovectorizing scanner and 

editing workstation, ARC/INFO running on a Prime computer, and the Scitex Response-280 editing workstation and 

plotter. All steps before Scitex processing are controlled by 

the user (for example, the project scientist or map editor). 

Our Method 3 
MANUSCRIPT 

MAP 

convert to 

ARC/INFO format ~ 

z 

prepare map to project and register w 

be scanned :E 

each map coverage z 

0 

a: 

~ > 

edit lines z ~ ffi ' scan and w 

z ·' >< o:E w a:Z ~ tag polygons and edit ~ 

~0 z 0 ~~ W> 

~z 

w 

edit 

GIS DATA 

BASE 

w 

::E 

z 

0 

a: 

> z 

w 

0 

u. 

z 

=:: 

0 

a: 

<C 

combine selected 

convert coverages 

to Scitex format 

en 

color separates 

(negatives) 

PAPER 

MAP 

Figure 1. Steps in digital production of maps by our method. GIS, geographic information system; ftp, file transfer 

protocol, a means for electronic data transfer; mag., magnetic. 

The method is summarized below and in figure 1: 

( 1) Author linework or scribed copy is scanned on the 

Tektronix 4991 autovectorizing scanner and automatically recorded onto the disk of the Tektronix editing 

workstation. 

(2) For each map separate, scanned linework is partially 

edited on the Tektronix workstation by using 

TekniCAD software. Map symbols and their leaders 

are removed, and most gaps in lines are repaired. 

This step may be omitted, and all editing may be 

done in ARC/INFO; the choice depends on the 

availability of equipment, the expertise of the editor, 

and the operations to be performed. 

(3) Edited map files are transferred by Ethernet cable and 

ftp (file transfer protocol) software to the computer 

4 A User's Manual for a Method of Map Scanning and Digital Editing 
that contains the ARC/INFO GIS software. If Ethernet is not available, Kermit software can be used. 

(4) Files are converted to ARC/INFO line coverages by a 

routine written by one of the authors (Lanfear). 

System software written since our method was 

established permits conversion of TekniCAD files 

to IGES (Initial Graphics Exchange Specification) format on the Tektronix workstation by the 

TCADIGES command and conversion of the 

IGES-format files to ARC/INFO coverages by the 

IGESARC command (T.T. Fitzgibbon, USGS, oral 

commun., 1990). 

(5) Prior to line and polygon editing, all coverages for a 

given map (for our test map, all coverages for a 

1: 1 ,000 ,000-scale quadrangle) must be precisely 

registered to each other; if necessary, the TRANSFORM command in ARC or the ADJUST command in ARCEDIT may be used. As part of this 

registration procedure, coverages are transformed to 

the appropriate map projection. 

(6) Lines are edited in ARCEDIT to ensure their continuity. Lines must be continuous before the correct 

polygon topology can be established. Editing efficiency is improved by using an AML (Arc macro 

language) program with pulldown menus, which 

was written by one of the authors (Lanfear). 

(7) Polygon topology is built, label points are placed in 

each polygon, and items are added, as needed, to 

the newly created polygon attribute table (.PAT). 

Polygon label points are assigned values, or tagged, 

by using the tag subroutine of Lanfear's ARCEDIT 

AML or another method, as discussed in section 

F-4. 

(8) The validity of map data is checked in ARCPLOT on 

a graphics display terminal. After any errors have 

been corrected in ARCED IT, electrostatic plots are 

generated for a final check. 

(9) Two coverages, character of surficial deposits and 

thickness of Quaternary sediments, are combined so 

that resultant polygons contain information from 

both coverages and can, therefore, be assigned 

unique map colors. Coverage items are renamed as 

appropriate, the coverages are merged with the 

UNION or INTERSECT command, and sliver polygons are removed with the ELIMINATE command. 

(10) The validity of map data is checked in ARCPLOT on 

a graphics display terminal. After any errors have 

been corrected in ARCED IT, electrostatic plots are 

generated for a final check. 

( 11) At this point, coverages can be developed into a GIS 

data base (not discussed in this report). 

(12) Coverages are converted to Scitex format with the 

ARCSCITEX or PLOTSCITEX command. 

(13) Files are written to magnetic tape. 

( 14) Files are read onto the Scitex system for generation of 

negatives. This procedure can be lengthy and complex.; it is briefly discussed in this report. 

About the User's Manual Format and Syntax 

Because this report is a user's manual, we have 

provided certain instructions on basic system commands 

and operations, such as operation of the autovectorizing 

scanner. These instructions are generalized; for further 

information, see the user documentation provided by the 

manufacturers. We assume that the user has at least a 

rudimentary knowledge of general map and cartographic 

concepts (for example, map projections), the PRIMOS and 

UNIX operating systems, graphics terminals, ARC/INFO, 

and file management concepts. General skills such as 

reading and writing to magnetic tapes, for file backup or for 

transfer of map data to other computer systems, are beyond 

the scope of this report. 

In this manual, all system and user dialog is indented 

and set off from the text by spaces. System prompts and 

information appear in normal (roman), uppercase and lowercase letters. For the Tektronix scanner and workstation, 

the system prompt in this manual is "system prompt>"; for 

PRIMOS, the system prompt is "OK,"; for ARC, it is 

"Arc:"; and for INFO, it is "ENTER COMMAND>". 

Within the system-user dialog, notes or instructions to the 

user are shown in italics. Commands entered by the user 

appear in uppercase BOLD type, except for the Tektronix 

commands, which appear in lowercase bold type. Command variables commonly appear in lowercase and are 

confined between angle brackets, < >. These command 

variables include file and coverage names. They can be 

entered in either uppercase or lowercase in ARC or in 

PRIMOS and are reported by these two systems in uppercase. In INFO, all commands and variables must be entered 

in uppercase letters. On the Tektronix, all commands and 

variables must be entered in lowercase letters. A carriage 

return (the return key) is shown as <cr>. 

A. Preparing for Map Scanning 

If the map to be scanned has dense, continuous lines 

of uniform thickness, then the digital map editing can be 

quick. Therefore, an author's lines may need to be scribed 

prior to scanning. In devising our method, we scribed the 

author's lines in order to minimize editing problems. Lines 

were scribed with a thickness (weight) of 0.004 in.; 

negatives that were used as scan copies had line weights of 

0.004-0.005 in. Thinner lines were tried (for example, 

0.002 in.), but they did not scan well; the lines were 

recorded as broken line segments because they were too thin 

to be consistently detected by the scanner, which has a 

resolution of 0.00328 in. (0.0833 mm). A thicker line was 

not used because of the tight spacing of the linework. 

A. Preparing for Map Scanning 5 
Latitude and longitude marks were added to each map 

separate for registration purposes; the marks were small 

crosses, not a grid of lines. 

For some maps, the author's linework may be 

scanned with good results. Choice of the type of scan copy 

is a matter of judgment and economy: if the author's 

linework is complex, or if the time allotted for editing is 

limited, scribing the linework is appropriate because it will 

yield a higher quality scan copy that needs relatively little 

editing. Aronoff (1989, p. 107) noted that map preparation 

(that is, redrafting or scribing) before manual digitizing can 

reduce the costs of digital capture by as much as 50 percent. 

If linework is not too complex, and if time and personnel 

can be allotted for map editing, it can be appropriate to use 

author's line work as the scan copy. We experimented with 

scanning the author's linework for the smallest sheet of the 

Quaternary sediments map and achieved satisfactory results 

because the linework was relatively dense and continuous. 

The author's linework has since been used as the scan copy 

for other parts of the Quaternary sediments map. 

B. Map Scanning 

B-1. Getting Started 

We used a Tektronix 4991 autovectorizing scanner, 

which is connected to a UNIX-based Tektronix model4325 

graphics workstation with graphics tablet. The workstation 

stores Tektronix scanning software (TekScan) and editing 

software (TekniCAD). TekScan controls all scanning operations and converts scanned data from raw vector format 

(. VEC file extension) to TekniCAD format (. TDA file 

extension). This scanning workstation is easy to use and can 

provide high-quality map data for GIS data bases and for 

thematic graphic reproduction. It is used in several USGS 

locations, and where one is housed in a USGS regional GIS 

research laboratory, it is accessible to all trained users. 

Before starting the scanning procedure, consult personnel responsible for the equipment and obtain their 

approval to operate it. To scan a map, log onto the 

workstation, and load the scan copy onto the scanner drum. 

Do not block the groove on the drum near its right edge, as 

the groove must be clear for the scanner to operate properly. 

If a negative or a clear-film positive is used, place the 

emulsion side against the drum for the better scan. Next, 

initiate the TekScan software: 

system prompt> tekscan <cr> 

This command causes the TekScan Main Menu to be 

displayed. The user responds to all TekScan menus by 

entering the number corresponding to the desired choice. 

The return key is not required when choosing from the 

menus. 

B-2. Setting the Scanning Parameters 

The user should select appropriate values for scanning parameters to optimize the quality of the digital output. 

Although default settings for scanning parameters are provided by TekScan, they are not optimal for most scan copies 

and should be used only as a guide. The user must modify 

the parameter settings to suit the copy medium and the 

quality and complexity of the linework. To view and 

modify the scanning parameters, select option 1 on the 

Main Menu to access the Scanner Control Menu: 

Main Menu 

1 . Change Parameters 

2. Start Scan and Convert VEC File to TekniCAD 

TDA File 

3. Start Scan 

4. Convert Scanned VEC File to TekniCAD TDA 

File 

5. Convert Scanned VEC File to GSS PIX File 

6. Convert GSS PIX File to TekniCAD TDA File 

7. Exit 

Please choose one of the above: 1 

After option 1 is selected, the Scanner Control Menu is 

displayed: 

Scanner Control Menu 

1. Show Scanning Parameters 

2. Change Scanning Parameters 

3. Show Drawing Environment Parameters 

4. Change Drawing Environment Parameters 

5. Show Communication/Display Parameters 

6. Change Communication/Display Parameters 

7. Read all Parameter Files (.TSS,.TSE,.TSC) 

8. Save all Parameter Files (.TSS,.TSE,.TSC) 

Please choose one of the above: 2 

After option 2 is selected from the Scanner Control Menu, 

the Scanning Parameters Menu is displayed; default parameters can be viewed and changed by selecting option 2. 

Scanning Parameters Menu 

1. Read Scanning Parameters from a File (.TSS) 

2. Enter New Scanning Parameters 

3. Save Current Scanning Parameters to a File 

(.TSS) 

Please choose one of the above: 2 

The following menu will appear: 

Scanning Parameters 

1 . Scan Units 

2. Background Type 

Metric 

: Light 

6 A User's Manual for a Method of Map Scanning and Digital Editing 
3. Dot Trapping Size 

4. Void Trapping Size 

5. Smoothing 

6. Reflectance Threshold 

7. Growing Layers 

8. Thinning Layers 

9. ScanArea 

A. Vectorizing Tolerance 

B. Short Vector Length 

C. Short Vector Tolerance 

D. Bell 

Please choose one of the above: 

sxs pixels 

1 pixel 

Enabled 

42% 

0 

2 

100.00, 300.00, 

100.00, 300.00 

0.097 

0.000 

0.000 

Enabled 

The default settings appear to the right of the colons. These 

default settings vary because users can redefine them. If 

option 1 had been selected from the Scanning Parameters 

Menu, then parameter settings would be read and displayed 

from a preexisting parameter file (.TSS). 

From this menu, the user can customize the parameter 

settings for each scan. Consult the Tektronix user's manual 

and operator's manual for complete information on the 

scanning parameters. Parameter settings can be modified in 

any order and can be modified more than once before 

exiting this menu. Certain parameters have only two possible settings, and the user can only alternate between the two 

settings by selecting that option number. Other parameters 

(for example, see "Reflectance Threshold" and "Scan Area" 

below) can accept a range of settings. The optimal settings 

depend on a number of factors, including the condition of 

the image to be scanned. To determine the best setting for 

parameters such as Reflectance Threshold, use the Scan 

Area parameter to select a small area of the image to scan as 

a test. Through an iterative series of test scans, optimal 

parameter settings can be determined. If you decide to use 

default settings, return to the Main Menu with the escape 

key. To retreat toward the Main Menu, one menu at a time, 

use the delete key. The scanning parameters are described 

below: 

Scan Units. -Choices for Scan Units are Metric 

(millimeters) or English (inches). The choice can be important to subsequent data-processing steps; map data are 

scanned in units of the chosen measurement system, and the 

unit of measure is retained in TekniCAD and in output files. 

Background Type. -Choices for Background Type 

are Light or Dark. Select Light for scanning positives, 

Dark, for negatives. Opaque media (paper copies) should 

be positioned on the drum face up; transparent media 

(negatives or clear-film positives) should have the emulsion 

against the drum surface. If placement of the appropriate 

side against the drum causes the map to be inverted (that is, 

if the map's east side is on the left side of the drum and if 

the south side is facing upward), then the Mirror Image 

parameter in the Communication/Display Parameters Menu 

must be set to On (see section B-3, "Setting Other 

Parameters"). 

Dot Trapping Size. -Discrete points of scanned 

information smaller than the selected Dot Trapping Size 

will be deleted automatically. This function is useful for 

deleting the scanned images of dust specks, which commonly adhere to the scan copy or drum. Choices are 1 x 1, 

3X3, or 5X5 pixels. Because pixels are quite small (0.0833 

mm or 0.00328 in. square) relative to thematic map 

linework, the maximum Dot Trapping Size (5X5 pixels) is 

recommended. 

Void Trapping Size. -Voids in line work are filled 

automatically. Size options for Void Trapping Size are the 

same as those for Dot Trapping Size. We used 1 x 1 pixel 

for Void Trapping Size because our lines were thin and our 

linework was closely spaced. 

Smoothing. -Choices for Smoothing are Enabled or 

Disabled. We recommend that Smoothing be enabled, 

which will cause 1-pixel-wide protrusions or indentations to 

be removed. The autovectorizer does this processing task 

after void and dot trapping. 

Reflectance Threshold.-The scanner determines 

what will be written to the digital file by comparing the 

reflectance of the pixel currently being scanned to the 

reflectance of the background. Reflectance is the ratio of 

reflected to incident light. The scanner senses linework on 

a map by bouncing a beam of light off the map and into a 

detector. If light reflected from the pixel is above the 

threshold value for dark Background Type or below the 

threshold value for light Background Type, then that pixel 

will be written to the digital file. Otherwise, that pixel will 

be considered to contain no data (for example, not part of a 

geologic contact line). For a light background map such as 

a clear-film positive with black linework, the background 

(actually the white drum surface behind the clear film) will 

reflect more light than the linework Therefore, for light 

background types, the linework will have relatively low 

reflectance and can be recorded to the digital file only if the 

reflectance threshold is sufficiently high. If the threshold is 

set too high, dirt smudges and perhaps even the film 

positive itself will be detected and recorded. This parameter 

affects the quality of the scan more than most, and its 

setting should be carefully determined by one or more test 

scans on a small part of the map (see "Scan Area" parameter 

discussion below). 

The Reflectance Threshold can be set from 0% to 

100% because the reflectance ratio is expressed as a 

percentage. For scanning a positive image, the threshold 

should probably be set between 40% and 50%. If the 

threshold is set too low, then line breaks will result. If the 

threshold is set too high, then tightly spaced lines will 

become fused together or will be bridged by short lines. For 

scanning a negative, the threshold should probably be set 

between 25% and 30%. For negatives, lower thresholds will 

cause fusing or bridging of tightly spaced lines, and higher 

thresholds will result in line breaks. 

B-2. Setting the Scanning Parameters 7 
Growing Layers.-In the Growing Layers procedure, 

a layer of pixels is added to all edges of scanned data, 

including lines and filled areas. Choices are 0, 1, or 2 layers 

of pixels. Adding layers of pixels will fill gaps within lines 

but may also fill gaps between tightly spaced lines; these 

filled gaps require additional editing time. On our scribed 

test map, high-quality lines had few irregularities and 

breaks. The scribed lines had a width of 0.004 in., which is 

quite narrow and close to the resolution of the scanner. For 

lines of this thickness and quality, we recommend setting 

the Growing Layers parameter to 0 pixels. The autovectorizer performs this processing task after Smoothing. 

Thinning Layers. -The Thinning Layers procedure 

removes layers of pixels from both sides of a line; the 

maximum reduction is to a line 1 pixel wide. This processing occurs after the Growing Layers procedure is completed 

for a line. Choices are for the removal of 0 to 7 pixels from 

each side of the line's center. Line gaps and areas filled 

during the growing operation are not affected by thinning. If 

lines are thinned too much, line spurs form, and T-shaped 

intersections may become distorted into Y -shaped intersections. On our scribed test map, lines had a width of 0.004 

in., which is quite narrow and close to the resolution of the 

scanner. For lines of this thickness, we recommend that the 

Thinning Layers setting be no more than 2 pixels greater 

than the Growing Layers setting (for our map, this meant a 

Thinning Layers setting of 2 or less). However, if thicker 

lines are to be scanned, then a higher Thinning Layers 

setting must be used to thin the lines to 1-pixel width. This 

thinning is necessary so that the autovectorizer can accurately convert the scanned line into a single vectorized line 

that traces the centerline of the scanned line. If a scanned 

line is much wider than 1 pixel, the autovectorizer cannot 

do this accurately, and it may produce a series of vectorized 

lines arranged as small boxlike forms or networks that 

together may imitate the form of the scanned line. 

Scan Area. -The Scan Area parameter defines the 

area to be scanned. This area may include the entire scan 

copy or a small portion of the copy. The optimal scanning 

parameters are selected by trial and error, and so it is useful 

to specify a small test area on the map that can be quickly 

scanned. In a series of trial scans within the test area, 

parameter settings can be varied and optimized. Upon 

selecting the Scan Area parameter, the user is prompted for 

the scan area, whose dimensions are measured along the 

edge of the loading platform (the x-axis) and the left edge of 

the scanning drum (they-axis). Dimensions must be defined 

in the scan units specified (millimeters or inches). The 

maximum scanning format is 870X 1,200 mm (34.5X47 

in.). 

Vectorizing Tolerance.-The Vectorizing Tolerance 

parameter sets the maximum perpendicular distance 

between a line on the scan copy and the vector that 

represents that line. By selecting values from 0 to 10 mm or 

0 to 0.5 in., the user determines how closely the vectors are 

to follow the original shape of the line. If the tolerance is set 

too high, then the vector data will have an angular appearance, and detail will be lost. If the tolerance is set too low 

(for example, below the scanner's limit of resolution, which 

is 0.0833 mm or 0.00328 in.), then the vector data may 

have a ragged or stairstep appearance caused by the vectors 

following the edges of pixels. Intermediate settings should 

provide acceptable line quality. However, because this 

parameter determines the amount of data needed to describe 

a line, file size varies as the inverse of the parameter setting. 

The appropriate setting is generally a compromise between 

the line quality and file storage limitations. For the map data 

from our test area, a tolerance ranging between 0.1 and 

0.095 mm provided lines with adequate detail and acceptable file size. However, for other types of maps, greater 

detail is required to preserve certain images. For example, 

to retain the accuracy and detail of strike and dip symbols 

on a map, a smaller tolerance may be needed. 

Short Vector Length.-The Short Vector Length 

parameter sets the maximum length for lines to be classified 

as short vectors. The range of values is from 0 to 50 mm (0 

to 1.97 in.). This parameter can be set to select features 

such as depression contour tic marks and save them to a file 

separate from the contour lines. For our test map, and 

probably for many other maps as well, this capability is not 

needed; select 0.0 if this procedure is not desired. 

Short Vector Tolerance.-The Short Vector Tolerance parameter is similar to the Vectorizing Tolerance 

parameter. Select 0.0 if the Short Vector Length is set to 

0.0. 

Bell. -Choices for the bell are Enabled or Disabled. 

If enabled, a bell will sound to verify the communication 

link between the autovectorizer and the workstation, to alert 

the user when scanning errors occur, and to signal completion of the scan. 

8-3. Setting Other Parameters 

After scanning parameters have been set, they can be 

saved to a parameter file. Return to the Scanning Parameters Menu by pressing the delete key. Save the parameter 

settings to a parameter file (.TSS) by selecting option 3 and 

specifying a file name. Otherwise, return to the Main Menu 

by pressing the escape key. 

The user may also want to modify certain default 

Drawing Environment or Communication/Display parameters. If so, choose option 1 from the Main Menu to reach the 

Scanner Control Menu. From the Scanner Control Menu, a 

number of drawing and communication/display options may 

be selected. The Drawing Environment parameters may 

need to be modified if the scanned data will be separated 

into two layers, one for short vectors and one for long 

vectors; for general scanning of linework, however, the 

default values should be used. Choose option 6 from the 

8 A User's Manual for a Method of Map Scanning and Digital Editing 
Scanner Control Menu to view and change the Communication/Display parameters: 

Scanner Control Menu 

1. Show Scanning Parameters 

2. Change Scanning Parameters 

3. Show Drawing Environment Parameters 

4. Change Drawing Environment Parameters 

5. Show Communication/Display Parameters 

6. Change Communication/Display Parameters 

7. Read all Parameter Files (.TSS,.TSE,.TSC) 

8. Save all Parameter Files (.TSS,.TSE,.TSC) 

Please choose one of the above: 6 

After option 6 is chosen from the Scanner Control Menu to 

display the Communication/Display Parameters Menu, 

default parameters can be viewed and changed by using 

option 2: 

Communication/Display Parameters Menu 

1. Read Communication/Display Parameters 

from a File (.TSC) 

2. Enter New Communication/Display Parameters 

3. Save Current Communication/Display Parameters to a File (.TSC) 

Please choose one of the above: 2 

The following menu will appear: 

Communication/Display Parameters 

1. TTY Port 

2. Debug 

3. Baudrate 

4. Display Scanned Image 

5. Long Vector Color (1-8) 

6. Long Vector Filled Area Color (1-8) 

7. Short Vector Color (1-8) 

8. Short Vector Filled Area Color (1-8) 

9. Mirror Image 

A. Rotate Image (Degree) 

Please choose one of the above: 

00 

: Off 

: 9600 

:On 

: 1 

:3 

:5 

:4 

: Off 

:0 

Default values are generally acceptable. If, however, 

the map must be inverted on the drum for optimum scanning 

(see the "Background Type" discussion above in section 

B-2, "Setting the Scanning Parameters"), then the Mirror 

Image option must be set to On. If, because of size, the scan 

copy cannot be placed on the drum with north pointing 

upward, use the Rotate Image option to position north to the 

top of the display screen if this is the desired viewing 

position. The system performs the Mirror Image conversion 

before the Rotate Image step; this sequence must be 

considered by the user in order to select the proper rotation 

angle. The Display Scanned Image option should be set 

to Off for background scanning (see discussion below); 

otherwise, it is commonly set to On in order to monitor the 

scanning progress. 

8-4. Initiating the Scan 

After all parameters have been set, return to the Main 

Menu and do the following: 

(1) Select option 2 ("Start Scan and Convert VEC 

File to TekniCAD TDA File") 

(2) Reply to system prompt for file name. 

Information on scanning progress is displayed during the 

scan. After the scan is complete, the Main Menu appears. 

The user commonly resets scanning parameters for the same 

copy or for a new scan or exits TekScan (select option 7). 

8-5. Background Scanning 

TekScan is commonly invoked interactively, and 

parameters are specified via the keyboard. While scanning, 

the workstation remains locked and cannot be used for any 

purpose other than to display the map as it is being scanned. 

Background scanning allows the user to run TekScan and, 

at the same time, to keep the workstation free for other 

activities, including file management, file transfer, and file 

editing in TekniCAD. Background scanning is made possible by creating a batch file that holds the responses to 

TekScan menus and prompts. The batch file consists solely 

of those numbers, letters, and special characters required to 

modify the system default parameters and run TekScan. To 

determine the batch file contents, the user must document, 

during a trial run, all the required TekScan responses. 

In the batch file, the commands could be arranged as 

follows: 

1222625 

9250 

730 

200 

850 

1\ [1624 1\ [2filename 

7 

The scanning session begins on the batch file's first line, 

with selection of option 1 (Change Parameters) from the 

Main Menu, then option 2 (Change Scanning Parameters) 

from the Scanner Control Menu, then option 2 (Enter New 

Scanning Parameters) from the Scanning Parameters Menu. 

The fourth number changes option 2 (Background Type) 

from light (this system's default value) to dark in order to 

scan a negative. The next number, 6, selects option 6 

(Reflectance Threshold), and the last two digits, 25, set the 

threshold at 25%. To enter the reflectance threshold, a 

carriage return is required, and it causes additional scanning 

B-5. Background Scanning 9 
parameter data to appear on the second and subsequent 

lines. The second line contains the Scan Area option (9) and 

the lower (left) x-coordinate in the default scan unit (millimeters), followed by a carriage return. The next three lines 

contain the upper (right) x-coordinate, the lower ycoordinate, and the upper y-coordinate, respectively. The 

sixth line concerns commands issued from the Main Menu, 

which is reached with the escape key. The escape command 

sequence "/\ [" is entered by typing "control-v" and the 

escape key. The sequence "1624" accesses the Communication/Display Parameters Menu and sets the Display 

Scanned Image option to Off. The Main Menu is again 

reached with the escape sequence, and option 2 (Start Scan 

and Convert VEC File to TekniCAD TDA File) is chosen. 

A user-defined file name is then specified, followed by a 

carriage return. The last line of the file selects option 7 (Exit 

TekScan). 

The UNIX vi editor can be used to create and edit the 

batch file. Invoke the vi editor as follows: 

system prompt> vi <batchfilename> <cr> 

The command must be given in lowercase letters, as 

required by the UNIX operating system. The screen will be 

blank except for a column of tildes ( ~) running down the 

left side. The vi editor has two modes, the command and the 

text edit mode. The command mode is active when the vi 

editor is started. To create the batch file, enter characters 

while in the text edit mode, which is commonly invoked 

with the "i" key. The following commands are commonly 

used to enter the text edit mode and to add text: 

inserts text before cursor 

inserts text at the beginning of line 

a appends text after cursor 

A appends text at the end of line 

o opens a new line below cursor 

0 opens a new line above cursor 

cw allows changes from cursor to end of word 

C allows changes from cursor to end of line 

cc changes entire line 

Characters entered after any of these input commands will 

write to the screen. To revert to command mode, press the 

escape key. 

Other commands reposition the cursor, delete text, 

and save the file. Commonly used commands are listed 

below: 

h moves cursor left 

I moves cursor right 

j moves cursor down 

k moves cursor up 

x deletes single character 

dw deletes word 

dd deletes line 

D deletes from cursor to end of line 

:wq saves file and quits vi 

ZZ saves file and quits vi 

Initiate the batch file as follows: 

system prompt> tekscan < batchfilename > 

<logfile> & 

A logfile must be specified, which will receive dialog such 

as scan menus and batch file commands. As an exception to 

this manual's syntax rules, "batchfilename" must be 

enclosed by blank spaces and angle brackets in this command only. 

C. Preliminary Editing Using TekniCAD 

C-1. Getting Started 

TekniCAD software allows the user to inspect and 

edit a scanned graphic. This is an interactive, menu-driven 

program, and it is invoked as follows: 

system prompt> teknicad <cr> 

TekniCAD displays three separate active areas on the 

workstation screen. The top display informs the user of 

functions being performed and of pen, level, and dash 

settings. The bottom display shows menus, messages, and 

options for which responses are required. The large center 

area is for the graphic display. Menu options can be selected 

by using the keyboard or by pointing to the command with 

the graphics tablet puck and pressing the yellow button on 

the puck. The puck can also be used for editing. 

The terminology used to describe lines is somewhat 

different from that used by ARC/INFO. A line (an arc in 

ARC/INFO) is composed of straight line segments; adjacent 

segments are separated by a point (a vertex in ARC/INFO). 

C-2. Displaying the Scanned Image 

To display a scanned image, enter the file name. 

If the file name is not known, enter "?" for a directory listing. In the directory, scanned images will be 

listed as "<filename>. TDD" (binary form) and 

"<filename> .TDA" (ASCII format) files. Enter the file 

name precisely as listed in the directory, and put the .TDA 

extension in uppercase letters. If the file doesn't exist, then 

a new one will be created. Press "?" for directory list or 

function key 4 for options: 

<filename.TDA (or"?")> <cr> 

The file will then be loaded into memory and drawn 

to the screen; the lower left comer of the screen is used as 

the origin. The TekniCAD Main Menu will appear in the 

10 A User's Manual for a Method of Map Scanning and Digital Editing 
lower display window. To center the image and make it fill 

the screen, 

(1) Select menu option 6 (Window/Grid). This will 

display the Select Window/Grid Function Menu. 

(2) Select menu option 3 (Min/Max) to redraw the 

image at maximum size. 

To view the image in more detail, local (hardware) 

zoom and pan can be performed at any time with function 

key 5. A menu will appear that gives the user various 

options and instructions. To zoom into an area, use the 

yellow button on the puck, or use the spacebar, to set the 

lower left and upper right corners of the area to be viewed 

in more detail. After the zoom operation, the system will 

revert to the last active menu. Press the escape key if access 

to the Main Menu is required. 

Local zoom and pan capability provides an essential 

tool for editing linework. However, for many maps, especially large ones with tight linework, local zoom and pan 

capability does not provide adequate resolution for identifying and editing features. Resolution at high magnification 

can be maximized by using the Window/Grid option to view 

an enlarged part of the map without loss of resolution. The 

local zoom and pan can then be used for slight magnification as needed to edit specific lines. This technique is 

similar to the ARC/INFO Mapextent and hardware zoom 

and pan technique described in section E-3. Proceed as 

follows: 

(1) Select option 6 (Window/Grid) from the Main 

Menu. 

(2) Select option 1 (Box). 

(3) With the puck, set the lower left and upper right 

corners of the window area. 

(4) Use local (hardware) zoom and pan, as needed, 

to edit the map. 

(5) Select option 3 (Min/Max) to redisplay the entire 

map. 

The user can create and save several windows for a 

map area in order to systematically edit the map in detail. 

To do so, select option 5 (Save), and designate a window 

number (as many as eight windows are allowed for each 

map). Use option 6 (Restore) to draw a window to the 

screen. Use option 3 (Min/Max) to redisplay the entire map 

after creating windows. 

C-3. Deleting Lines 

To edit the linework, go to the Main Menu (press 

escape key if necessary). Use the following steps in order to 

select and color, or tag, lines that must be deleted: 

(1) Select option 2 (Delete/Copy/Edit). 

(2) Select option 3 (Modify). 

(3) Select option 3 (Pen). 

(4) Select a number to indicate pen color; for example, "<2 (red)> <cr>." 

To identify lines and spurious information (for example, dust specks detected by the scanner) to be deleted by a 

subsequent set of commands: 

Select option 7 (Region). 

Then use the yellow button on the puck, or use the 

spacebar, to set the lower left and upper right corners of the 

box. Lines that lie completely within the boxed area will 

then be colored (red if pen color 2 was selected, as above). 

To select a new region, press any key to proceed. 

If it is later noted that a line has been incorrectly 

tagged for deletion, the line can be recovered by retagging 

it with pen color 1, the default color. To reassign the pen 

color, retreat two operations by using the green button on 

the puck or the keyboard's delete key to locate the Modify 

Function Menu. Reassign the pen color to 1, and select the 

appropriate line or lines with the Region option. 

To delete tagged lines, press the escape key to return 

to the Main Menu. Choose the Delete option and the pen 

color of the lines to be deleted: 

(1) Select option 2 (Delete/Copy/Edit). 

(2) Select option 1 (Delete). 

(3) Select option 3 (Pen). 

(4) Select a number to indicate pen color. 

(5) <cr> 

The system then prompts the user to specify the lower left 

and upper right comers of a box (by using the yellow button 

on the puck or the spacebar) that contains all the lines 

tagged (colored) for deletion. When the upper right comer 

is specified, all tagged items are deleted. Next, press any 

key. Define more boxes and delete lines or press the escape 

key to leave this function. 

To delete single segments from either end of a line, 

return to the Main Menu and do the following: 

(1) Select option 2 (Delete/Copy/Edit). 

(2) Select option 3 (Modify). 

(3) Select option 1 (Item). 

This selection displays a cursor, which is used to identify a 

line, or segments of that line, for deletion. Position the 

cursor on the line and 

Select option L. 

The selected line flashes, and a menu appears. Then 

Select option 1 (Modify points). 

This option highlights (in the selected pen color) all 

segments that form the selected line. The first point of that 

line is highlighted with arrows. In order to delete the first 

point and the first line segment, 

C-3. Deleting Lines 11 
Select option 2 (Delete). 

The delete option highlights the next point and can be 

repeated indefinitely to delete additional points and line 

segments. To recover all of the original line, press the 

escape key. To select another line or to return the cursor to 

the screen, 

Select option 6 (Change complete). 

To delete a line segment somewhere after the first 

point and line segment (for example, the segment at the 

other end of the line), 

Select option 7 (Go to point N). 

Enter the appropriate point number from the point range of 

1 to n. To delete the other endpoint and the attached line 

segment, enter the n value and <cr>. This highlights the 

other endpoint for deletion. As an alternate method, use 

option 1 (No change), which moves the highlighter through 

subsequent points. To delete the point and line segment, 

Select option 2 (Delete). 

Select or respond to "Change complete?" to complete the 

operation. 

C-4. Repairing Line Breaks 

To repair breaks, or gaps, in lines, go to the Main 

Menu, access the Modify Function Menu, select the Item 

option, and select the line that needs to be extended to fill 

the gap. The command sequence is 

(1) Select option 2 (Delete/Copy/Edit) from the Main 

Menu. 

(2) Select option 3 (Modify). 

(3) Select option 1 (Item). 

(4) Select option L. 

(5) Select option 1 (Modify points). 

The "Modify points" option highlights the selected line and 

the starting point. Line segments can be created only from 

the highlighted point. If the line segment next to the line 

break is attached to the starting point, then 

Select option 4 (Insert before). 

If the point to which a line segment must be added is located 

at the opposite end of the line from the starting point, then 

(1) Select option 1 (No change) or option 7 (Go to 

point N) to access the other end of the line. 

(2) Select option 5 (Insert after). 

Options 4 and 5 display a line attached to the point, which 

can then be pulled by the cursor and attached to another 

line. Complete the process as follows: 

(1) Select option L. 

(2) Select option 6 (Change complete). 

If the default cursor is not desirable, a simplified cursor can 

be selected by simultaneously pressing shift and function 

key 6. 

For certain line breaks, TekniCAD responds to 

options 4 (Insert before) or 5 (Insert after) with the message, 

"No line item found inside pick aperture." This response is 

common for a single line that should completely bound a 

polygon. To correct the line break and thereby close the 

polygon, the single line must be divided so that the nodes on 

either side of the line break do not belong to the same line. 

In the following procedure, this is accomplished by redefining each line segment as a new line. To respond to the 

screen message, 

Select option 6 (Change complete). 

Select the line again and 

Select option 3 (Explode all segments). 

This command "explodes" the line into several lines, 

each being a line segment of the original line. Normal 

editing procedures for closing a line break can now be 

performed. 

C-5. Repositioning Points and Line Segments 

Use the Replace option in the Modify Function Menu 

to reposition a point and its associated line segments. 

Position the cursor on the line segment to be modified, 

highlight the appropriate point, and move it to a new 

location. The Replace option permits a replacement location 

to be identified for the point by use of the yellow button on 

the puck or by use of the spacebar. The point and attached 

line segments are then repositioned. From the Main Menu, 

proceed as follows: 

(1) Select option 2 (Delete/Copy/Edit). 

(2) Select option 3 (Modify). 

(3) Select option 1 (Item). 

( 4) Select option L. 

(5) Select option 1 (Modify points). 

(6) Highlight the appropriate point with option 1 or 7. 

(7) Select option 3 (Replace). 

(8) Select option 6 (Change complete). 

For step 7, use the puck to position the cursor in the desired 

location, then press the yellow button on the puck or press 

the spacebar to move the point. After all points have been 

repositioned ("replaced") as needed, or points have been 

added or deleted, proceed to step 8 (Change complete). 

12 A User's Manual for a Method of Map Scanning and Digital Editing 
C-6. Tracing Linework 

For some maps, even the optimum scan parameters 

produce a map of poor quality, with many line breaks and 

extraneous lines. Rather than editing the file, it may be 

more efficient to trace the linework, using the scanned map 

as a template. This approach may also be chosen for maps 

containing dashed lines, which must be converted in digital 

form to continuous lines so that each dashed line can be 

identified as a single feature rather than as many separate, 

and therefore unassociated, short lines. Each line can later 

be assigned an attribute in ARC/INFO so that it will display 

as a dashed line. 

To trace linework, go to the Main Menu, define a 

new color for tracing linework, and trace the lines: 

(1) Select function key 8. 

(2) Select a number to indicate pen color. <cr> 

(3) Select option 1 (Geometry). 

(4) Select option 1 (Line). 

(5) Select option 1 (Free Input/Smooth). 

(6) Select option l. 

Option L requires that a point be identified. From the point, 

trace the line segments with the puck while depressing the 

yellow button. Use the green button on the puck to delete 

traced line segments that are incorrectly drawn. If the 

default cursor is not desired for tracing, a simplified cursor 

can be selected by simultaneously pressing shift and function key 6. To stop the line trace, press <cr>. To terminate 

the traced line at a point on another line, press 1 and <cr>. 

To trace a line precisely, press L instead of the yellow 

button on the puck to attach new line segments to existing 

points along the scanned line. All traced line segments are 

identified in the selected pen color. 

To extract the traced coverage from the original 

linework, use the Blanking option, which saves linework by 

color. To use it, press the escape key to return to the Main 

Menu, then 

(1) Select option 2 (Delete/Copy/Edit). 

(2) Select option 4 (Blank). 

(3) Select option 3 (Pen). 

(4) Select a number to indicate the pen color for 

lines to be "blanked" (for example, 1 indicates the 

default color). 

(5) <cr> 

The system then requests the user to set the lower left and 

upper right comers of a box. When the upper right comer is 

set, all linework of the chosen color will be removed from 

the box shown on the screen. This procedure may appear to 

cause a breakup of the traced linework; if so, use a screen 

refresh such as zooming or redrawing to restore the screen 

image. 

C-7. Saving Edited Linework and Exiting TekniCAD 

To save traced linework, return to the Main Menu and 

do the following: 

(1) Select option 7 (Drawing/Symbol). 

(2) Select option 1 (Dwng; Save). 

(3) Select function key 4 to see options. 

(4) Select option 2 (Unblanked items only). 

(5) <cr> 

(6 <file name for traced lines> <cr> 

(7) <file description> <cr> 

The file description is optional; a single <cr> is allowed in 

its place. Unless otherwise specified, the traced file is saved 

to a .TDD format file. Specify the .TDA extension 

(<filename. TDA>) to simplify the procedure for later 

transfer to the ARC/INFO environment. 

To save an edited file without exiting TekniCAD, 

return to the Main Menu and do the following: 

(1) Select option 7 (Drawing/Symbol). 

(2) Select option 1 (Dwng; Save). 

(3) <filename> <cr> 

(4) <file description> <cr> 

Then, another file can be edited: 

(1) Select option 2 (Dwng; Restore). 

(2) <filename> <cr> 

To save an edited file and end the TekniCAD session, 

return to the Main Menu and do the following: 

(1) Select option 9 (End Session). 

(2) system prompt> Do you want to end this drafting 

session (Y,N)? <Y> 

(3) system prompt> Do you want to save it (Y,N)? 

<Y> 

C-8. Saving Files to Backup Tape 

Files should be saved onto a backup medium, such as 

a floppy disk or a tape cartridge. Cartridges are preferred 

because of their higher storage capacity; a 600-ft cartridge 

can store about 60MB (megabytes) of data. To write files 

to tape, move to the root directory above the user's working 

directory and specify the files to be saved. Check with the 

system administrator first, as access to the root directory 

may be restricted. The following dialog shows how to copy 

the entire directory, individual files, or all files of a certain 

type (for example, .TDA format) by using the wildcard 

symbol, an asterisk (*): 

C-8. Saving Files to Backup Tape 13 
system prompt> cd/ (move to one directory 

above the working directory) 

NOTE: The following command will write the entire 

directory to tape: 

system prompt> 

cpioout /usr/<directoryname> /& 

NOTE: The following command will write individual 

files to tape: 

system prompt> cpioout /usr/<filename (with full 

pathname) > I& 

NOTE: The following command will write files of a 

specified type to tape: 

system prompt> cpioout /usr/<files of a certain 

type (for example, "*.TDA")> /& 

NOTE: The term "cpioout" and the file designation 

must each be followed by a blank space. 

YOUR CPIO TAPE IS COMPLETE 

END/DONE 

system prompt> logout 

The tape-writing command can also be executed from 

within the user's working directory. To do this, issue the 

command "cpioout" without arguments if all files are to be 

copied to tape. If a selected subset of files is to be saved, 

use the commands listed above. 

To reload the files from tape, ensure that adequate 

disk space is available and that files of the same name do 

not exist on both the workstation disk and the tape. Then, 

do the following: 

system prompt> cpioload . 

NOTE: The term "cpioload" must be followed by a 

blank space and a period. 

C-9. Deciding Whether to Edit in TekniCAD or ARC/INFO 

The TekniCAD editing functions discussed above can 

also be performed in ARC/INFO. Although some functions 

may be less efficient in ARC/INFO, certain operations (for 

example, detecting and correcting line breaks) may be 

easier in ARC/INFO. The user may perform all editing in 

either TekniCAD or ARC/INFO or may use both software 

systems. For our project, we used both. TekniCAD was 

used for the preliminary edit, to remove extraneous lines, to 

reposition lines as needed, and to close as many line breaks 

as possible. Final line inspection and editing were done in 

ARC/INFO. We had access to, and experience on, both 

systems. Other users may not. When designing the editing 

procedures for a map, the user must consider availability of 

personnel, their level of expertise on the two systems, and 

the availability of equipment. There are two advantages to 

performing all editing in ARC/INFO: first, most users are 

familiar with it, and, second, most users have ready access 

to it. The TekniCAD system is relatively unfamiliar to 

many people. Perhaps more significantly, the Tektronix 

workstation is configured for only a single user, which 

limits access time for every project. Although we consider 

the TekniCAD editor to be a useful tool, for many projects, 

the cost- and time-efficient procedure may be to scan maps 

with TekScan, inspect them in TekniCAD, and send the 

unedited data to ARC/INFO for line editing. 

D. Transferring the Map Data to the ARC/INFO 

Environment 

The map files, in either unedited or edited form, must 

next be transferred to a computer that contains ARC/INFO 

software. We used ARC/INFO on the Reston, Va., GIS 

laboratory's Prime computer. We transmitted files electronically from the Tektronix scanning workstation to the Prime 

computer via ftp (using the Ethernet cable) or Kermit 

software. Ethernet transmits the data much faster and may, 

therefore, be the preferred course. Using Ethernet and ftp 

software, the procedure is as follows: 

system prompt> ftp <computer call letters 

(for example, qvarsf)> 

username ( ): <user's 10 on the destination 

computer> 

Password: <user's password on the destination 

computer> 

NOTE: The user is now logged onto the destination 

computer and is positioned in the user's top-level 

directory. The scanned files will be transmitted 

here unless a different destination directory is 

chosen, as follows: 

ftp: cd <full pathname for destination directory 

(for example, user>maps)> 

NOTE: If desired, enter the following command to 

list the directory's contents. 

ftp: Is 

NOTE: Use the following command to transmit . TDAformat files, one at a time: 

ftp: put <filename1 >.TDA 

ftp: put <filename2>.TDA 

..... . etc ...... . 

ftp: quit 

For large files (for example, those contammg 30 

MB), the time needed to transfer the data can be as long as 

several hours. For such a file, it may be preferable to log 

onto the Prime computer from another terminal and use an 

adaptation of the above procedure for data transfer. After 

invoking ftp on the computer, log onto the Tektronix 

scanning workstation from the remote terminal, attach to 

the correct directory on the Tektronix with the cd (change 

directory) command, and "get" rather than "put" the files. 

Files will then be copied from the Tektronix onto the 

computer. 

After the files are transferred, the map data reside as 

Tektronix .TDA-format files in a directory on the Prime 

computer. These files must be converted to ARC/INFO 

format. We use a conversion routine written by one of the 

14 A User's Manual for a Method of Map Scanning and Digital Editing 
authors (Lanfear). This user-created ARC/INFO CPL (command procedure language) routine reads the Tektronixformat input file, converts the file to an ARC/INFO line 

coverage via ARC's GENERATE command, and builds 

line topology with the "BUILD <coverage> LINE" command. A coverage is ARC/INFO terminology for a map 

data file in ARC/INFO format. Before beginning the data 

conversion, the CPL queries whether the file has been 

edited in TekniCAD or merely scanned. Unedited files have 

a slightly different format than TekniCAD-edited files, and 

the CPL is designed to read both types. Since our method 

was established, system software has been written that 

permits conversion of TekniCAD files to ARC/INFO coverages via the IGES (Initial Graphics Exchange Specification) format (T.T. Fitzgibbon, USGS, oral commun., 

1990). TekniCAD files are converted to IGES-format files 

on the Tektronix workstation by using the TCADIGES 

command. These files are then converted to ARC/INFO 

coverages with the IGESARC command. 

To convert a file to ARC/INFO format, log onto the 

Prime computer and go to the directory containing the file. 

If the . TDA or IGES file was transmitted into the user's 

upper level directory, and if the user would prefer that the 

map data reside in a subdirectory, then create a subdirectory 

and copy the . TDA or IGES file: 

OK, CREATE <subdirectory> 

OK, DOWN <subdirectory> 

OK, COPY <filename.TDA (with full pathname) > 

To invoke Lanfear's conversion CPL, do the following: 

OK, R KJL1>UTILITY>TEK>CONVERT-TEK.CPL 

INPUT FILE NAME: <filename.TDA> 

OUTPUT COVER NAME: <newfilename> 

Has the file been edited on the scanner? <YES or 

NO> 

NOTE: After this response, the computer issues 

processing statements that require no response. 

Arc: 

Reading large files and converting them to 

ARC/INFO coverages can be a lengthy operation. Therefore, for large files, this routine should be executed in batch 

mode. 

The newly generated ARC/INFO coverage exists as a 

subdirectory named "newfilename." That subdirectory contains several ARC and INFO files that need not be directly 

accessed by the user. For most ARC/INFO users, the 

coverage is treated as a file, not a subdirectory, and is 

accessed and manipulated from the directory above. It is 

common practice for the directory within which a coverage 

(subdirectory) resides to contain two or more coverages that 

are related by geography or topic. 

E. Preparing ARC/INFO Coverages for Editing 

As discussed above, our method was tested on a map 

having four overlays, or separates. These separates were 

each processed into an ARC/INFO coverage. Before these 

coverages could be edited, they needed to be converted to a 

map projection and then registered to each other. The 

procedure is described below. 

E-1. Initiating ARC/INFO and Describing the Display 

Device 

We initiated ARC/INFO from the PRIMOS operating 

system. Much of our final method testing was done with 

ARC/INFO version 5.0.1; however, the following procedures should be fully applicable with earlier (ARC 4.0 

level) software revisions as well. When the user invokes 

ARC/INFO, certain characteristics of the terminal or workstation may be specified. Although this information is most 

critical to the graphics subroutines of ARC/INFO (for 

example, ARCEDIT), the most convenient time to supply 

this information may be when ARC/INFO is invoked, not 

when ARCEDIT or ARCPLOT is invoked. To save time, 

the sequence of commands listed below can be programmed 

to a function key (see the operator's manual for the terminal 

for details). The DISPLAY parameter specifies the type of 

graphics terminal. The TERMINAL parameter sets terminal 

characteristics for dialog display and pulldown menus. The 

method of selecting pulldown menu options (for example, 

by cursor or mouse) must be specified after the TERMINAL 

command unless the default device (cursor) will be used. To 

speed editing in ARCED IT, and especially if pulldown 

menus are to be used, a mouse is preferred to the cursor. 

The "device #" is the terminal's model number (for 

example, "4207" for a Tektronix 4207). 

OK, ARC 

(C)1988-1990 Environmental Systems Research 

Institute, Inc. 

All Rights Reserved Worldwide 

ARC Version 5.0.1 

Arc: DISPLAY <device #> 

Example: DISPLAY 4207 

Arc: &TERMINAL <device#> &<input 

device (for example, MOUSE)> 

Example: & TERMINAL 4207 &MOUSE 

E-2. Copying Coverages 

Usually, the new coverages should be stored and 

edited in a directory that contains only coverages related by 

geography or topic. If the .TDA files were not transmitted 

into such a directory prior to conversion to ARC/INFO 

coverages, create a new directory in PRIMOS, enter that 

directory, invoke ARC, and copy the new coverages to the 

directory as follows: 

E-2. Copying Coverages 15 
OK, CREATE <subdirectory> 

OK, DOWN <subdirectory> 

OK, ARC 

Arc: COPY <coverage (with full pathname)> 

<new name for coverage (if original coverage 

name is acceptable, press <cr> instead)> 

If coverages (and their associated INFO directory) 

have been copied into the subdirectory without using the 

COPY command in ARC/INFO, for example by using 

magnetic tape or by copying the entire directory with the 

COPY command at the PRIMOS level, then pointers to the 

associated INFO files (for example, .AAT, .TIC) must be 

reset as follows: 

Arc: EXTERNAL <coverage> 

. . . . . . or ..... . 

Arc: EXTERNALALL (corrects the INFO file pointers for all coverages in the working directory) 

This procedure must be done before the coverages are 

edited and before INFO files are viewed and modified, 

because failure to do so results in a damaged coverage that 

may be very difficult to recover. 

E-3. Adding Latitude-Longitude Tic Marks to Each 

Coverage 

Each map separate that is scanned should contain 

latitude-longitude intersection marks that can be converted 

into ARC/INFO tics. These tics are control points that 

permit coverages to be projected into the proper geographic 

space. They are essential for establishing precise registration among coverages. The latitude-longitude marks should 

appear as scanned crosses when the linework is displayed 

on the screen. In ARCPLOT, inspect each coverage and 

select the one with the least linework around the crosses and 

the least distortion of the arcs that form the crosses: 

Arc: ARCPLOT 

ARC PLOT: MAPE <coverage #1 > 

ARCPLOT: ARCS <coverage #1 > 

ARCPLOT: CLEAR 

ARCPLOT: MAPE <coverage #2> 

ARCPLOT: ARCS <coverage #2> 

ARCPLOT: CLEAR 

..... . etc ..... . 

ARCPLOT: QUIT 

Arc: 

Next, invoke ARCEDIT. We suggest using an 

ARCEDIT menu-driven AML (arc macro language) program such as EDITI.AML, which was written by one of the 

authors (Lanfear). Using EDITI.AML, the dialog in 

ARCEDIT might proceed as follows: 

Arc: &R KJL 1 >UTILITV>EDIT1.AML 

Procedure EDIT1 .AML, Version 3.2 

Programmed by Kenneth J. Lanfear, USGS 

Invokes ARCEDIT with a menu 

User supplied menu (<cr> = default): <cr> 

Input map name: <coverage name> 

Output map name (<cr> = input map): <cr> 

OK to modify the input map? V 

Renumber IDs? N 

If the answer to the "Renumber IDs?" query is "yes," 

then the program renumbers the coverage ID's and performs 

an !DEDIT on the attribute tables. For this edit session, this 

step is not necessary, so an,.swer "no" to the query. Next, the 

AML loads ARCEDIT, selects "coverage name" as the 

"EDITCOVER" (the coverage to be edited), and selects 

"ARCS" as the "EDITFEATURE" (the feature to be 

edited). A pulldown menu is then displayed . 

For most coverages, precise registration with other 

coverages is desired, and this requires accurate placement 

of an adequate number of tics. However, to register some 

maps, it may be sufficient to simply move the four existing 

tics to new positions that correspond to latitude-longitude 

intersections (the scanned crosses). Commands to select the 

four tics, one at a time, and move them are issued from the 

pulldown menus as follows: 

Menu: SELECT Command: EDITF TIC 

Menu: DRAW Command: DRAWENV ... 

DRAWENVIRONMENT: TIC IDS 

Menu: DRAW Command: DRAW 

Menu: DRAW Command: Mapextent * 

NOTE: The Mapextent * command allows a part of 

the coverage to be displayed in greater detail. 

Hardware zoom and pan may then be used to 

enlarge the image for even more accurate tic 

placement. If precision is not critical, omit the 

Mapextent * procedure and use only the hardware zoom and pan. See discussion below on 

the use of Mapextent * and hardware zoom and 

pan. After viewing an enlargement of a map area 

containing a tic, select the tic, and move it to the 

proper location. 

Menu: SELECT Command: SELECT 

Menu: EDIT Command: MOVE 

NOTE: The MOVE routine will prompt for the location to move the feature from (place mouse or 

cursor at the tic's current position) and the location to move the feature to (place mouse or cursor over the latitude-longitude intersection). 

Moving the four tics may be useful for certain 

coverages. For example, a scanned cultural base may form 

a very large coverage that would require a long time (20 

minutes or more) to draw to the screen. If this base will be 

used solely as a background display image and if precise 

registration is not critical, then satisfactory placement of 

tics may be done rapidly by using hardware zoom and pan. 

The four existing tics could be moved, or the old tics could 

16 A User's Manual for a Method of Map Scanning and Digital Editing 
be deleted and new tics added to match the tics in coverages 

with which the base will be displayed. In either case, the ID 

number for each tic must match that for tics in corresponding locations in the other coverages (see additional discussion on this matter below). 

Although the above procedure has value in certain 

applications, we do not recommend it for coverages where 

precise registration is important. For most applications, we 

recommend that the user begin by deleting the coverage's 

four existing tics because the latitude and longitude of these 

tics cannot be determined; unless their locations can be 

precisely defined in decimal degrees, they cannot be used to 

project the coverage. New tics should then be added as 

outlined below. Commands to select the four existing tics 

and delete them are issued from the pulldown menus as 

follows: 

Menu: SELECT 

Menu: SELECT 

Menu: EDIT 

Command: EDITF TIC 

Command: SELECT ALL 

Command: DELETE 

Add new tics to the coverage at the latitude-longitude 

intersections. Remember, the lines that appear at those 

intersections are arcs, not tic marks; they cannot be used as 

tic marks in the map projection procedure that will follow, 

and eventually they should be deleted from the coverage. 

Add the tics in a systematic manner, perhaps moving from 

the upper left comer of the coverage to the lower right 

comer. We recommend using 8 to 12 tics. The tics and their 

ID numbers must be the same for each coverage, and we 

suggest recording, on paper, the location and ID number of 

each tic. In order to more precisely locate the position of 

each tic, use either the terminal's hardware zoom and pan or 

ARC/INFO's MAPEXTENT command. We suggest viewing an enlargement of part of the coverage by using 

MAPEXTENT *, then using hardware zoom and pan to 

greatly enlarge the area containing a latitude-longitude 

intersection. This procedure will place the tic more accurately than would using hardware zoom and pan alone. 

Menu: DRAW Command: DRAWENV ... 

DRAWENVIRONMENT: TIC IDS 

Menu: DRAW Command: DRAW 

Menu: DRAW Command: Mapextent * 

NOTE: The MAPEXTENT * command in this AML 

also causes the selected area to be drawn and 

eliminates the need to issue another DRAW command. 

Menu: EDIT Command: ADD 

NOTE: The system will then display the ADD Menu: 

1) Add Tic 3) New User-10 5) Delete last tic 

6) New symbol 7) Autoincrement OFF 8) Autoincrement ON 

9) Quit 

(Tic) User-10: 5 Coordinate = 

Although the four preexisting tics have been deleted, 

the system will nevertheless add tics beginning with tic 5. In 

order for tics to be numbered sequentially beginning with 1 , 

select ADD Menu option 3 (New User-ID). The 

EDIT1.AML now requires the user to select "ARCEDIT 

command" from the SYS Menu and to input the desired tic 

ID number after the "ARCEDIT:" prompt. This procedure 

must be followed for the first four tics; thereafter, tics will 

be correctly numbered by the system. 

After adding tics to the intersections within the 

redefined Mapextent, use MAPEXTENT LAST (an 

EDITl.AML choice) or MAPEXTENT DEFAULT to 

return to the mapextent that shows the entire coverage. 

Then view an enlargement of another area by using 

MAPEXTENT *. After all tics have been added, inspect the 

tics and save the edited coverage: 

Menu: DRAW 

Menu: SVS 

Command: Mapextent last 

(or DEFAULT) 

Command: Save and QUIT 

Add tics to the remaining coverages and ensure that 

tic locations and their ID numbers correspond among all 

coverages. For some coverages, linework may interfere 

with, or obscure, certain latitude-longitude intersections. 

Rather than guessing at the proper location, do not add a tic 

there. For the next tic to be added to that coverage, select 

option 3 (New User-ID) from the ADD Menu to advance to 

the appropriate ID number. It is not essential that all 

coverages have the same number of tics, but each tic ID 

number must correspond to tics in the same geographic 

position in all coverages. 

E-4. Converting Tic Coordinates from Scanner Units to 

Latitude and Longitude 

The coordinates of each tic in a coverage must be 

converted from scanner units to latitude and longitude so 

that all coverages can later be projected and transformed 

into the proper geographic space. Before conversion, a 

new, empty coverage (that is, one that contains no point, 

arc, or polygon information) must be created by using the 

tic information of one of the map coverages. The first 

coverage processed in section E-3 has the best placement 

and most complete array of tics and should be used as that 

map coverage (it is the "firstcoverage" in the dialog section 

below). Then, the INFO software is used to convert tic 

coordinates for the empty coverage from scanner units to 

latitude and longitude: 

Arc: CREATE <emptycoverage> 

<firstcoverage> 

Arc: INFO 

INFO EXCHANGE CALL 

WED, DEC 20, 1989 

INFO 9.42 12/ 1/86 52.74.63* 

COPYRIGHT 1986 HENCO SOFTWARE, INC. 

PROPRIETARY TO HENCO SOFTWARE, INC. 

E-4. Converting Tic Coordinates from Scanner Units to Latitude and Longitude 17 
US GOVT AGENCIES SEE USAGE RESTRICTIONS 

IN HELP FILES (HELP RESTRICTIONS) 

ENTER USER NAME> ARC 

NOTE: INFO will not accept entry of lowercase letters, which are used here to distinguish command variables, such as coverage names, from 

commands, as discussed in "About the User's 

Manual Format and Syntax." 

ENTER COMMAND> SEL 

<emptycoverage> .TIC 

ENTER COMMAND> IT or L1 

NOTE: "IT" is the abbreviation for "ITEMS," which 

lists the names and formats of items in the . TIC 

file. For a . TIC file, the items are IDTIC, XTIC, and 

YTIC. XTIC = Longitude (negative values in the 

Western Hemisphere), and YTIC = Latitude (positive values in the Northern Hemisphere). "LI" is 

the abbreviation for "LIST"; it lists the internal 

record number ("$REGNO"), /OTIC, XTIC, and 

YTIC value for each tic. 

ENTER COMMAND> UPDATE BY IDTIC 

IDTIC?> <tic number (for example, 1)> 

IDTIC 

XTIC 

YTIC 

?> XTIC 

?> YTIC 

?> <cr> 

IDTIC?> 

= 1 

= 475.2 

= 329.6 

= -84.0 

= 46.0 

After converting all tic coordinates, press <cr> after 

the IDTIC?> prompt to exit to the ENTER COMMAND> 

prompt. Review the tic file with the LI command, then exit 

INFO as follows: 

ENTER COMMAND> Q 

ENTER USER NAME> STOP 

Arc: 

E-5. Selecting a Map Projection and Projecting the Empty 

Coverage 

Determine the map projection of the scanned copy 

and project the empty coverage according to the following 

example. The tic positions, presently in latitude and longitude coordinates, will be converted to the specified unit of 

measure and arranged in the selected coordinate system and 

projection. The ".prj" extension is not mandatory; it is used 

here solely to identify the projected coverage. 

Arc: PROJECT COVER <emptycoverage> 

<empty.prj> 

Please define the input and output map projections. 

Use INPUT to define the input projection, OUTPUT to 

define the output projection, and END to finish. 

Project: INPUT 

Project: PROJ GEOGRAPHIC 

Project: UNITS DO (for decimal degrees) 

Project: PARAMETERS 

Project: OUTPUT 

Project: PROJ LAMBERT 

Project: UNITS METERS 

Project: PARAMETERS 

1 st standard parallel: 46 30 00 

2nd standard parallel: 48 30 00 

central meridian: -107 30 00 

latitude of projection's origin: 47 30 00 

false easting (meters): 0 

false northing (meters): 0 

Project: END 

Arc: 

E-6. Transforming Coverages to Map Projection 

Coordinates 

At this stage, each coverage containing map data is 

unprojected, and all map information is in x- and ycoordinates recorded by the scanner in either millimeters or 

inches. The TRANSFORM function converts the map 

information to the map units and map projection specified in 

the previous step (section E-5) by using the tics in the 

empty coverage "empty. prj" as a template. For the TRANSFORM function to operate successfully, each coverage to 

be transformed must contain at least some (and as many as 

possible) of the tics that are contained in the "empty. prj" 

coverage. Also, tic ID numbers and locations of tics must 

agree between coverages. Before transforming the coverages, create one copy of "empty.prj" for each coverage to 

be transformed. Then, the TRANSFORM function will 

place a transformed copy of a coverage's map data into the 

empty coverage that has been copied from "empty.prj." 

Commonly, each copy of "empty. prj" is named as 

some variation of the name of the original, unprojected map 

coverages. For example, if an unprojected coverage is 

named "GEOLOGY" (represented as "coverage# 1" in the 

following dialog), then the copy of "empty. prj" could be 

named "GEOLOGY2" (represented as "coverage# 1. prj" in 

the following dialog). Successive modifications of the 

coverage, such as those made after line editing or polygon 

tagging, can be denoted by higher numbered coverages (for 

example, "GEOLOGY3," "GEOLOGY4"). 

Copy the empty coverage and transform the map data 

as follows: 

Arc: COPY <empty.prj> <coverage#1.prj> 

Arc: COPY <empty.prj> <coverage#2.prj> 

. . . do this for each of the coverages to be transformed ... 

Arc: TRANSFORM <coverage#1 > 

coverage#1.prj> 

Transforming coordinates for coverage 

COVERAGE#1 

NOTE: Transformation data will appear here. 

Arc: 

18 A User's Manual for a Method of Map Scanning and Digital Editing 
The displayed transformation data include values for 

the RMS (root-mean-square) error, which is a measure of 

the degree of fit between the tics of the input coverage 

(coverage# 1) and the tics of the empty coverage 

(coverage# 1. prj). If the RMS error is high, the map data 

will be somewhat distorted by the transformation. Common 

sources of a high RMS error are tics that are poorly located 

on the source materials, tics that were poorly located using 

ARCED IT's ADD command, or mismatches of tic ID 

numbers. If tic ID numbers are mismatched, edit them in 

INFO by using the UPDATE command, delete the ".prj" 

coverage (with the ARC KILL command), and execute the 

transformation again. The range of acceptable RMS values 

will vary depending on the map scale and accuracy of the 

map data; therefore, as recommended in the ARC/INFO 

manual, a guideline for acceptable RMS values may be 

established for a given map project. 

E-7. Delineating the Boundaries of Maps Lacking Neatlines 

Maps are commonly enclosed within a neatline, 

which is a carefully positioned map outline that may or may 

not be defined by lines of latitude and longitude. Some 

scanned maps do not have neatlines, or they have neatlines 

that are improperly positioned or of inadequate line quality. 

Neatlines or some sort of bounding lines must be added to 

the map's arc information if the map is to have polygon 

information. This section describes several techniques and 

commands that are widely applicable to processing coverages; here, they are used to create a neatline, truncate or clip 

the map's line coverage at the neatline, add the neatline to 

the line coverage, and edit the arcs to establish the desired 

arc-node topology. 

To create a new coverage containing the neatline, the 

GENERATE command may be used with either the GRID 

or the LINE subcommand. The GRID subcommand is 

particularly useful for generating a latitude-longitude grid 

overlay for a coverage, and GRID can be used to create a 

neatline, although that procedure is not discussed here. A 

simple, straightforward method for generating a neatline is 

shown below. This method creates a neatline whose lines, 

defined by latitude and longitude, outline a quadrangle. 

Note the coordinates of the quadrangle corners, invoke 

GENERATE with the LINE subcommand, and enter starting and ending coordinates for the four lines that form the 

neatline: 

Arc: GENERATE <coverage (for example, 

neatline}> 

Generate: LINE 

NOTE: If needed, online help is available for the 

specified command (for example, HELP LINE). 

Enter Lines. 

Terminate Line by entering END at X,Y: prompt. 

Terminate input by entering END at ID: prompt. 

NOTE: The system will prompt for a line ID number 

that will be associated with the line coordinates 

entered after the X, Y: prompts. For the first X, Y: 

prompt, enter the coordinate pair for a quadrangle corner; X = Longitude (negative values in the 

Western Hemisphere) and Y = Latitude (positive 

values in the Northern Hemisphere). For the second X, Y: prompt, enter another coordinate pair to 

define a side of the neatline. From these two 

coordinate pairs, GENERATE can create a line 

that forms one side of the neatline. For the third 

X, Y: prompt, enter END to receive another ID: 

prompt. Proceed as described above until the 

four sides of the neatline have been defined by 

pairs of x- and y-coordinates. 

ID: <line number> 

X,Y: <starting coordinate pair (for example, 

-96,40}> 

X,Y: <ending coordinate pair (for example, 

-96,44)> 

X,Y: END 

ID: <etc.> 

ID: END 

Generate: QUIT 

Externalling BND and TIC ... 

Arc: 

This procedure results in a box, whose four sides are 

composed of arcs described only by starting and ending 

coordinate pairs. Because it is described by geographic 

coordinates, this box is not yet a usable neatline; it must be 

converted to the projection used for the map coverages. 

However, before the neatline is projected, its arcs may need 

to be modified. Neatlines for the Quaternary sediments map 

define 1:1 ,000,000-scale quadrangles in the Lambert projection system. At this scale and projection, lines of latitude 

are curved. To obtain a curved line when the neatline is 

projected, additional coordinates (vertices) must be added 

to the arcs of latitude. The process of adding vertices to an 

arc is called densifying the arc. Because only the lines of 

latitude are curved for this map, only they must be densified. They can be selected in ARCEDIT and densified 

interactively with the DENSIFY command, or all four arcs 

of the neatline can be densified automatically at the Arc 

level with the DENSIFY ARC command. The following 

example uses the ARCEDIT approach. Although the 

EDITl.AML menu commands are not given in the example, this procedure is facilitated by the EDITl.AML program or other pull down menu programs. 

ARCEDIT: EDITCOVERAGE <neatline> 

ARCEDIT: EDITFEATURE ARC 

NOTE: Draw the neatline coverage by issuing 

DRAWENVIRONMENT ARC and DRAW. 

ARCEDIT: SELECT MANY 

NOTE: Select the top and bottom arcs (the lines of 

latitude). 

ARCEDIT: DENSIFY <distance> 

E-7. Delineating the Boundaries of Maps Lacking Neatlines 19 
NOTE: The distance specified in the DENSIFY command refers to distance between added vertices, 

in coverage units. Because the neatline is 

described in geographic coordinates, the coverage unit is decimal degrees. For our maps, a distance of .05 might be appropriate. To select 

appropriate distance values, the vertices can be 

drawn by issuing the SETDRAWSYMBOL 2 command to change drawing colors and VERTEX 

DRAW. If vertex spacing is inappropriate, issue 

the OOPS command three times to undo the 

VERTEX DRAW, SETDRAWSYMBOL 2, and 

DENSIFY commands. See section F-1 for more 

discussion of the OOPS command. Select the 

appropriate distance by trial and error. 

ARCEDIT: SAVE 

ARCEDIT: QUIT 

Next, project the neatline and build polygon topology 

in preparation for integrating the neatline into the map 

coverage. After the topology is built, the CLIP command is 

issued to remove arc segments in the map coverage that lie 

outside the neatline. In the following example, "neatline" is 

the unprojected neatline, and "neatline2" is the projected 

neatline. 

Arc: PROJECT COVER <neatline> <neatline2> 

NOTE: Refer to the discussion of projection commands in section E-5. 

Arc: BUILD <neatline2> 

NOTE: Use the default POLY option for the BUILD 

command, which need not be specified after 

"neatline2." 

Arc: CLIP <input map coverage> 

<neatline2> <output (the "clipped") map 

coverage> LINE 

NOTE: We used the default fuzzy tolerance in the 

CLIP command. If a fuzzy tolerance is specified, 

enter it after the LINE argument. 

The CLIP command truncates arcs at the edge of data 

in the clip coverage ("neatline2" in the above example), but 

it does not add the neatline to the map coverage. The 

neatline must be added to the coverage in ARCED IT, and 

proper arc-node topology must be established. The CLIP 

command does not cause the position of the truncated arc to 

be perfectly matched to the neatline position in the clip 

coverage. Therefore, if the clip coverage is later added to 

the map coverage, truncated arcs may fall short of, or 

extend beyond (overshoot), the neatline. Because the truncated end of such an arc is not connected to another arc, it 

is referred to as a dangling arc. These topological errors 

should be corrected in ARCEDIT and in Arc. The 

ARCEDIT EXTEND command identifies a truncated arc, 

searches within a specified distance, and, if another arc is 

found, extends the truncated arc to meet that arc. Before 

executing the EXTEND command, the user should remove 

dangling arcs in the coverage's interior area so that the 

EXTEND command does not create undesirable arc-node 

topology within the map coverage. For example, the 

latitude-longitude intersections, or crosses, may consist of 

four dangling arcs, each joined to the others in the center of 

the cross. It may be advisable to remove these crosses (see 

step 1 of section F-2) before issuing the EXTEND command. However, the crosses probably will not be extended 

to other nearby arcs because the distance argument to the 

EXTEND command will be set at a very short distance that 

should not cause most dangling arcs to be connected to 

another arc. In the following dialog section, the neatline is 

added to the map coverage, and the desired arc-node 

topology is established with the EXTEND and CLEAN 

commands: 

ARCEDIT: EDITCOVERAGE <map coverage> 

ARCEDIT: GET <neatline2> 

NOTE: Draw the map coverage, and select and 

delete (perhaps by using SELECT BOX) the 

latitude-longitude crosses and other dangling 

arcs in interior parts of the map coverage. 

ARCEDIT: GRAPHICS OFF 

ARCEDIT: EDITFEATURE ARC 

ARCEDIT: SELECT ALL 

ARCEDIT: EXTEND BOTH <distance> 

NOTE: The distance is in coverage units. Select a 

very small distance. For our coverages, we used 

a distance of about 10 m. After the command 

has executed, the number of dangling arcs remaining can be viewed by turning GRAPHICS 

ON and drawing the coverage with DRAWENVIRONMENT NODE DANGLE. The EXTEND 

command may be reissued with a larger distance 

to check if more dangling nodes exist inside the 

neatline. Because dangling nodes can also be 

attached to arc overshoots, the EXTEND command will not resolve all dangling arcs. 

ARCEDIT: SAVE 

ARCEDIT: QUIT 

NOTE: The following command reestablishes proper arc-node topology and integrates the neatline 

into the map coverage ("output map coverage" in 

the following example). 

Arc: CLEAN <input map coverage> 

<output map coverage> # # LINE 

NOTE: We used the default fuzzy tolerance in this 

example, although for some maps, the default is 

not appropriate; see section F-2. As will be noted 

by comparison of the preceding command line 

with examples given in the ARC/INFO manual, no 

input is required if the default value for an argument is chosen, unless it is followed by an argument for which the default value is not chosen. 

Then, # must be used to specify the default 

value. After the coverage has been cleaned, invoke ARCEDIT, inspect the coverage and delete 

any dangling arcs outside the neatline, and exit 

20 A User's Manual for a Method of Map Scanning and Digital Editing 
ARCEDIT. If any arcs were deleted, issue the following command: 

Arc: BUILD <output map coverage> LINE 

The map coverage is now bounded by a precisely 

defined neatline and has proper arc-node topology. 

E-8. Checking and Adjusting Registration 

In ARCEDIT, check the registration of all coverages 

by selecting an EDITCOVERAGE and drawing the other 

coverages as BACKCOVERAGES. If all scan copies could 

be registered to each other, then coverage registration 

should be precise. In certain cases, however, registration is 

not acceptable. To correct misregistrations, two techniques 

may be used: transformation or rubber-sheeting. Transformation is a linear conversion of one coverage's coordinates 

to another's and is performed in ARC; rubber-sheeting is an 

interactive method of adjusting a coverage that is commonly 

done in ARCED IT. Transformation is commonly used to 

correct a uniform shift or misregistration, and rubbersheeting is used to correct more localized distortions and 

misregistrations of map data. 

The transformation technique is easier to implement 

and is based on coverage tics. Identifiable reference points 

in one coverage are compared with the same points in 

another coverage; this comparison is used to determine a 

least-squares linear transformation for converting all arcs 

and label points. To transform a coverage, first select the 

coverage (the target coverage) to which other coverages will 

be registered. It is prudent to work with copies of the 

coverages, and so, before proceeding, copy each coverage. 

In ARCEDIT, delete existing tics in all coverages. For the 

target coverage and the coverages to be transformed, 

inspect for features such as uniquely shaped parts of arcs 

that are shared by the coverages and that should, therefore, 

occupy identical geographic positions. For example, if both 

coverages contain the same shoreline, look for distinctive 

shoreline configurations that are identifiable on both coverages. For identical positions on such features, place a tic 

and assign the same tic ID number for all coverages. We 

recommend placing 8 to 12 tics in each coverage to get the 

best results. When this is done, save each coverage and quit 

ARCEDIT. Create an empty coverage ("coverage.prj") 

possessing the tics of the target coverage, and transform the 

coverage as follows: 

Arc: CREATE <coverage.prj> 

<targetcoverage> 

Arc: TRANSFORM <coverage> 

<coverage. prj> 

If coverages still do not register properly, adjust the 

positions of tics and (or) add more tics to "coverage" and 

"targetcoverage," delete the old "coverage. prj" by using the 

KILL command, create a new "coverage.prj," and transform "coverage" again. 

This technique relies on placement of tics at features 

common to all coverages. Many coverages do not have 

enough, or any, common features. Then, there are two 

choices: offset estimation or rubber-sheeting. If the amount 

of misregistration, or coverage offset, can be estimated, tics 

can be placed in the target coverage and then can be placed 

in the other coverages in locations that are offset by the 

estimated distance. If TRANSFORM does not produce the 

desired result, then adjust tics in the transformed coverage 

until, by trial and error, the transformed and target coverages register. 

Rubber-sheeting is somewhat similar to offset estimation, but it is more effectively implemented for some 

coverages. Rubber-sheeting is more difficult to learn than 

transformation, but it can be a powerful, interactive tool for 

salvaging misregistered coverages by using ARCEDIT or a 

combination of ARCEDIT and ARC. However, because it 

is a powerful and flexible tool for distorting coverages, it 

must be used with caution. If rubber-sheeting is not applied 

carefully and methodically, the effects of the commands can 

be hard to predict, and a coverage can be distorted in ways 

not intended by the user. 

The need for rubber-sheeting to bring coverages into 

proper registration may indicate that the scanned map was 

distorted in some way. This problem is probably most 

common with non-scale-stable base material such as paper, 

especially if it has been folded. Also, if the projection of the 

scanned map has not been correctly determined, distortions 

that require rubber-sheeting may result upon conversion of 

the map from its assumed projection into some desired 

projection in order to match related coverages. Determining 

the correct projection of the scanned map may eliminate the 

need for rubber-sheeting. 

Some of the commands required for rubber-sheeting 

are unique and are not listed in EDITl.AML; therefore, we 

performed rubber-sheeting by invoking ARCEDIT without 

the AML. If ARCEDIT is not invoked by EDITl.AML, 

and if a mouse will be used to identify the linked features, 

then COORDINATE MOUSE must be specified. If a cursor 

must be used for graphic input because a mouse is not 

available, then magnification using MAPEXTENT * is 

particularly important to ensure proper placement of the link 

points. Rubber-sheeting involves the "linking" of features 

in the target coverage (the SNAPCOVERAGE) and in the 

coverage to be rubber-sheeted; "free points" are identified 

on the rubber-sheeted coverage, and corresponding "snap 

points" are identified on the target coverage. The effects of 

rubber-sheeting diminish, by a mathematical function, 

away from linked features. However, the limits of rubbersheeting can be set with LIMIT ADJUST BOX. The maximum distance that a feature will be moved should be close 

to the greatest degree of misregistration between the two 

E-8. Checking and Adjusting Registration 21 
coverages, and it is set with the SNAPPING CLOSEST * 

command. The ARCEDIT dialog may proceed as shown 

below. However, the ARC/INFO (volumes 1 and 2) and 

ARCED IT user's manuals should be consulted before using 

this technique, because the following command sequence is 

but one of many that can be used to rubber-sheet a 

coverage. 

ARCEDIT: COORDINATE MOUSE 

ARCEDIT: EDITCOVERAGE <coverage> 

ARCEDIT: BACKCOVERAGE 

<targetcoverage> <linecolor 

(for example, 2)> 

ARCEDIT: DRAWENVIRONMENT ARC 

ARCEDIT: BACKENVIRONMENT ARC 

ARCEDIT: DRAW 

ARCEDIT: MAPEXTENT * (if needed to view an 

enlargement of an area) 

ARCEDIT: DRAW (if previous step is performed) 

ARCEDIT: EDITFEATURE LINK 

ARCEDIT: SNAPCOVERAGE <targetcoverage> 

ARCEDIT: LINKFEATURE ARC ARC 

ARCEDIT: SNAPPING CLOSEST * 

Enter 2 points defining the distance (by using the 

mouse) 

ARCEDIT: LIMITADJUST BOX 

Define the box (by using the mouse to identify lower 

left and upper right corners) 

Limiting box has an area: 23929.370 and a perimeter: 

2244.081 

Deleting all links falling outside of limiting area ... 

Adding the perimeter of the limiting area as identity 

links ... 

ARCEDIT: ADD 

- - - - - - - - - - - - - - - Options - - - - - - - - - - - - - - -

1) Free point 2) Snap point 3) Set symbol 

9) Quit 

Link #111 : locate free point on editcoverage, 

press 1, then locate corresponding snap point on 

target coverage and press 2 

Link # 112 : repeat steps in Unk # 111 for other 

points 

Link #113 : <9> 

2 link(s) added to "FULL PATHNAME>COVERAGE" 

ARCEDIT: ADJUST 

Adjusting coverage "FULL 

PATHNAME>COVERAGE" 

Building the adjustment structure from the links for 

the first pass ... 

Proximal tolerance set to 79.425 ... 

Generating convex hull... 

Building Triangular Irregular Network ... 

adjusting ARCs ... 

adjusting LABELs ... 

adjusting ANNOTATION ... 

Updating the adjustment structure for the second 

pass ... 

adjusting ARCs ... 

adjusting LABELs ... 

adjusting ANNOTATION ... 

ARCED IT: 

NOTE: Display coverages and check for proper 

registration. If more adjustment is required, see 

discussion in next paragraph. If registration is 

acceptable, save the coverage, quit ARCEDIT, 

and rebuild the coverage's topology: 

ARCEDIT: SAVE 

ARCEDIT: QUIT 

Arc: BUILD <coverage> <POLY or LINE> 

NOTE: Use the LINE option unless the rubbersheeting is performed after polygon topology has 

been built. POLY is the default option; therefore-, 

if a polygon coverage is being rubber-sheeted, 

then the user does not need to specify an option. 

If, after ADJUST is executed, "coverage" does not 

register to the target coverage, then it can be adjusted 

further by adding links until the desired results are 

achieved. However, because of the compounding effects of 

linking and adjusting, the nature of subsequent adjustments 

may be difficult to predict. It may, therefore, be easier to 

use the OOPS command to undo the adjustment. OOPS 

must be issued twice, first to undo the adjustment, and then 

to undo the addition of links. New links can then be added, 

and the coverage can be adjusted. Even so, it is still difficult 

to predict the changes in line positions caused by linking 

and adjusting. It may be desirable, therefore, to save the 

adjusted coverage and display it as a backcoverage for 

comparison while adding new links either to a copy of the 

original coverage or to a copy of the adjusted coverage. 

After rubber-sheeting has been completed, topology should 

be rebuilt by using the BUILD command. 

F. Editing the Coverages in ARCED IT 

F-1. Setting Up an ARCEDIT Session 

From the ARC environment, invoke ARCED IT, 

preferably by an AML with pulldown menus (for example, 

EDITI.AML). Because of the command-intensive nature of 

ARCED IT, it is most efficient to select commands and edit 

a coverage by using a mouse rather than a cursor as the 

graphic input device. Draw the editcoverage, redefine the 

Mapextent as needed, and use the hardware zoom and pan 

to enlarge an area sufficiently for convenient editing. Set 

the EDITDISTANCE (search tolerance for selecting features) and the SNAPDISTANCE (tolerance for snapping 

nodes). If the * option is used for these parameters, then the 

distances can be set interactively on the display screen by 

defining two points with the cursor or mouse. These 

parameters are particularly important when arcs are being 

added or edited. Proceed with the edit session, redefining 

the Mapextent as needed via the DEFAULT, Last, and * 

options. During editing, any operations performed that are 

later regretted (for example, unintentional deletions of data) 

can be undone by using the OOPS command. Each time the 

OOPS command is issued, the previous operation is 

22 A User's Manual for a Method of Map Scanning and Digital Editing 
undone, and the data set is restored to its former condition. 

If the mistake has been followed by three operations, or 

transactions, such as feature selections, additions, or deletions, the OOPS command must be issued three times. A 

record of edit transactions is kept by ARCED IT, and it can 

be reviewed with the AUDITTRAIL command and the 

BRIEF or FULL option. However, certain information 

issued by ARCEDIT is in binary format and is contained in 

the AUDITTRAIL file; these binary commands are not 

readable and may cause problems if the file is listed to a 

printer. 

F-2. Cleaning Up the Linework 

Before polygons are built and label points are added, 

each coverage should be edited to remove unwanted lines 

(arcs in ARC/INFO), repair any gaps in lines, and adjust the 

positions of selected lines. Linework that has been fully 

edited in TekniCAD also must be inspected and edited 

because some line errors may appear after conversion to 

ARC/INFO format and map transformation. Editing steps 

are described below. 

( 1) Select and delete all arcs that compose the latitudelongitude intersection marks. 

(2) Where linework crosses a latitude-longitude intersection mark, the linework will likely be distorted 

during scanning. After removing the intersection 

mark, reposition the linework. 

(3) Check for line gaps by drawing the coverage with the 

DRA WENVIRONMENT NODE DANGLE option. 

Line gaps occur where arcs end in a node that is not 

shared with another arc (that is, the node "dangles" 

from the end of an arc). These nodes will be 

highlighted; then the user can rapidly identify and 

correct the line gaps with the ADD command. 

(4) Check each coverage for the small, extraneous arcs that 

may be introduced between tightly spaced lines by 

the scanner or the ARC/INFO GENERATE command. Commonly, line work is also distorted near 

areas containing these small arcs. Remove these 

unwanted lines and adjust the positions of lines to be 

retained. 

(5) If a coverage was extensively edited in TekniCAD, 

many arcs may exist where a single, longer arc could 

suffice. These arcs commonly formed when the 

TekniCAD explode command was used to close 

polygons originally composed of a single line (see 

section C-4). The Arc UN SPLIT command provides 

the fewest arcs that can describe the coverage. See 

section F-8 for details on the UNSPLIT command. 

This command can significantly reduce file size and 

time needed to redraw a coverage on the screen. For 

one of our coverages, 3,071 arcs were unsplit into 

1 ,099 arcs, and file size was reduced by one-third. 

(6) If previous steps (in sections E and F) have been 

completed, coverages should be registered. However, check again for proper registration with related 

coverages, especially in areas of tightly spaced linework. To display the related coverages, use the 

BACKCOVERAGE command with the symbol 

option to specify a different color. Reshape arcs or 

delete and replace arcs as needed, using commands 

including SELECT, ADD, DELETE, SPLIT, 

MOVE, VERTEX DRAW, VERTEXMOVE, VERTEX ADD, and VERTEX DELETE. 

(7) Review all coverages for errors in line quality and 

registration. Save the editcoverage and quit 

ARCEDIT. 

(8) BUILD all coverages with the LINE option: 

Arc: BUILD <coverage> LINE 

If the BUILD operation fails because some intersecting arcs were created during the editing session, correct the 

problem, as discussed in section F-7, and rebuild the 

coverage. If the BUILD operation continues to fail, topology can be established with the CLEAN command, which 

can correct errors in linework. The CLEAN command is a 

powerful tool that redefines the geographic position of all 

features. Therefore, it should not be used routinely to 

rebuild topology. Once topology has been established, use 

the BUILD command instead whenever possible. The only 

argument required by CLEAN is the coverage to be 

cleaned. The other arguments have default values. The 

fuzzy tolerance argument must be carefully considered, 

because it is a measure of map resolution and defines the 

extent to which arcs can be moved during the "cleaning" 

process. If the fuzzy tolerance is set too high, then arcs will 

become misplaced; if the tolerance is set too low, then the 

command will require an excessive amount of computer 

time. For coverages similar in size and scale to the 

quadrangles making up the Quaternary sediments map, the 

ARC/INFO rule for calculating the default fuzzy tolerance 

is (width of the BND)/10,000, which is roughly 5 m. 

Considering that the map was compiled, and will be 

published, at 1:1,000,000 scale, we judged this level of 

resolution to be unnecessarily high. We selected a 50-m 

tolerance as a compromise between resolution and computer 

processing time. 

F-3. Ordering the ID Numbers in the Attribute Tables 

When the user edits, adds, or deletes arcs or label 

points in ARCEDIT, ID numbers in the coverage's attribute 

tables are modified. When the user exits from ARCED IT, 

the coverage's topology must be rebuilt. If the coverage 

requires any further editing or processing with INFO, 

potentially fatal problems may arise because the ID numbers in the attribute tables no longer match ID numbers in 

the coverage's coordinate files. Most coverages require, at 

F-3. Ordering the ID Numbers in the Attribute Tables 23 
some time, some form of INFO processing such as recalculation of item values. We, therefore, advise the user to be 

cautious and avoid a potentially unusable data base by 

performing the following procedure after editing and 

rebuilding a coverage. This procedure recalculates the ID 

numbers in the arc and polygon attribute tables so that they 

correspond to the ARC/INFO internal number for each arc 

or label feature. ARC/INFO internal numbers are designated as "<COVERAGE>#". The !DEDIT command 

matches features in the coordinate files to the attribute 

tables. It also informs the user if more than one polygon 

label point remained in a given polygon when the previous 

edit session ended; this information can also be obtained by 

the LABELERRORS command. Note that below, and for 

any INFO commands, correct syntax is essential; uppercase 

letters must be used, and all operators (for example, =, +) 

must be surrounded by blank spaces. 

ARCEDIT: During the edit session, arcs and label 

points are moved, added, or deleted. After 

editing is done, SAVE the coverage and QUIT 

ARC EDIT. 

Arc: BUILD <coverage> 

NOTE: If the coverage is rebuilt successfully, perform the following steps. If errors exist in the coverage that prevent it from being rebuilt, reenter 

ARCEDIT. If EDIT1.AML is being used, the NO 

option for Renumber IDs? must be selected. Correct the error(s) (see discussion in section F-7), 

and try to BUILD the coverage again. If the 

BUILD command repeatedly fails to rebuild the 

topology, use of the CLEAN command must be 

considered, as discussed in section F-2. 

Arc: INFO 

ENTER COMMAND> SEL <coverage>.PAT 

(if it exists) 

ENTER COMMAND> CALC <coverage>-ID = 

<coverage># - 1 

ENTER COMMAND> SEL <coverage>.AAT 

(if it exists) 

ENTER COMMAND> CALC <coverage>-ID = 

<coverage># 

ENTER COMMAND> Q 

ENTER USER NAME> STOP 

Arc: IDEDIT <coverage> POLY 

Arc: IDEDIT <coverage> LINE 

This procedure is contained as an option (Renumber 

IDs?) in the setup part of EDITI.AML. Users might also 

find it helpful to create a separate AML to perform the 

INFO update and !DEDIT procedure. Its use on a coverage 

whenever the user is unsure of the correspondence of 

records among the coverage's various ARC/INFO files may 

prevent serious problems. 

F-4. Adding Polygon Information to Each Coverage 

A coverage's linework must be edited to final form, 

or to some acceptable interim level, before proceeding 

further. If errors such as line gaps and extraneous lines that 

form polygons have not been corrected, then the process of 

adding polygon attribute information will be slowed. 

Before polygon attribute information is added, polygon topology must be built, and an item or items must be 

added to the newly created polygon attribute table (.PAT). 

The additional item(s) are needed to differentiate the polygons (for example, by geologic unit or lithology). For each 

new item, a format must be specified. We commonly use a 

format of "4 5 B" for items identifying the type of polygon 

or the hardware shadeset color to be assigned to a polygon. 

Character information can also be contained in items so 

specified. If output to DLG1 (digital line graph) format is 

desired, items must be named "MINOR I", "MINOR2", 

and so on, and must be accompanied by a major item (for 

example, MAJOR!, MINOR!). The minor items must have 

the format "6 6 I", and the major items must have the format 

"3 3 I". If DLG output is needed, but items that identify 

polygon type are not properly named and formatted, those 

item values can be placed in the properly formatted item by 

using the CALCULATE command in INFO. See section 

G-4 for discussion of the ARC-to-DLG conversion. 

Label points may then be added to the coverage 

interactively or by a single command. Although we chose 

not to use the interactive method, it may be preferable for 

certain maps. To add label points interactively, the user 

may lay the map on a digitizing table or view the map on the 

terminal screen and add label points one at a time, assigning 

item values during the session or after all labels have been 

added. This technique allows the user to select the location 

of the label point, thereby minimizing the chances that 

blank polygons or multiple label points in a polygon will be 

produced upon conversion to Scitex format. The shape of 

polygons and placement of label points may have some 

bearing on whether, upon output to the Scitex, label points 

will remain associated with the proper polygon. Polygons 

that are long, narrow, and curved may be especially 

vulnerable to having their labels disassociated from them. 

The choice of techniques is largely a matter of 

personal preference and the distribution of map units. We 

chose the automated approach, which, for our data set, 

yielded few problems on the Scitex. The automated 

approach uses the CREATELABELS command. The last 

argument to this command, id-base, specifies the initial 

<COVERAGE>-ID number. If 0 (zero) is chosen, as in 

the example below, new labels will be added to all 

polygons, and the <COVERAGE>-ID will equal the 

polygon's internal number minus one. Add the label points 

as follows: 

Arc: BUILD <coverage> (with the default POLY 

option) 

1

Information on DLG's is available from the USGS, 510 National 

Center, Reston, VA 22092. 

24 A User's Manual for a Method of Map Scanning and Digital Editing 
NOTE: For large coverages, the BUILD operation 

with the default POLY option may take a long 

time to execute. Therefore, it would be appropriate to perform the BUILD in batch mode. 

Arc: ADDITEM <coverage>.PAT 

<coverage>.PAT <item (for example, 

"GEOLOGY")> <format (for example, 4 5 B or 

6 61)> 

Arc: CREATELABELS <coverage> 0 

For convenience, several items of the same format 

can be specified within a single argument in ADDITEM. 

For example, if each polygon in coverage MT must be 

tagged with MINORl and MINOR2 codes of the format 6 

6 I, as required for DLG output, the command could appear 

as follows: 

Arc: ADDITEM MT.PAT MT.PAT 

(! MINOR1 ,MINOR2 !) 6 6 I 

Next, invoke ARCEDIT and draw the coverage after 

specifying "DRAWENVIRONMENT ARC, LABEL." Use 

hardware zoom and pan to enlarge a part of the coverage; 

the degree of magnification must be a compromise between 

reducing the number of label points to a manageable 

number and retaining enough of the coverage to allow ready 

identification of polygons. Because features will not be 

added or removed, the MAPEXTENT * zoom technique 

need not be used. 

For each field of view, tag all the polygons for each 

map unit. The TAG Menu in the EDITl.AML may speed 

this process. It prompts for an item name, the value to 

assign to that item, and a DRA WSYMBOL color. Each 

label point that should have that item value is selected 

interactively and tagged. To follow this procedure, invoke 

EDITl.AML, select DRAWENVIRONMENT LABEL and 

DRAW commands from the DRAW Menu, select the 

EDITF LABEL command from the SELECT Menu, then 

select the "Tag with number" command from the TAG 

Menu. This last command invokes the following dialog: 

Item name (CR = last item assigned): <item name 

(for example, MINOR1 )> 

Value to assign: <value (for example, 101)> 

Color number (CR = current drawsymbol): 

<drawsymbol #> 

1 = Select 2 =Next 3 =Tag 9 = Exit 

The Select, Next, Tag, and Exit options allow the user to 

interactively select and tag each polygon of a given map 

unit, as defined by the chosen item name. 

For character information, use the "Tag with character" command, or issue the MOVEITEM command after 

selecting "ARCEDIT command:" from the Sys Menu. The 

characters must be enclosed by single quotation marks. To 

assign character information to a selected label point, issue 

the MOVEITEM command as follows: 

MOVEITEM <'character information' (for 

example, 'qal')> TO <item name> 

Character information is often entered incorrectly. As a 

result, several different misspellings of a unit identifier such 

as a geologic formation name can occur. We prefer the 

simplicity inherent in using numeric data to represent 

character information. Label points are more easily tagged, 

and the chances of mislabeling are somewhat reduced. A 

table relating the character information to unique numbers is 

needed by the user when tagging the label points. Character 

information will not be discussed further in this report. 

One map unit at a time, all label points within the 

field of view should be tagged. When all label points have 

been tagged (and colored if the TAG subroutine of 

EDITl.AML is being used), use hardware pan to view 

another part of the map. Proceed systematically across the 

map. When tagging and coloring are completed, redraw the 

coverage. Redrawing will cause all colored label points to 

revert to the default (white). Check for untagged polygons 

by selecting for label points with the default value; untagged 

polygons will retain the default value ofO (zero). Draw any 

selected label points in another color by using the SETDRA WSYMBOL and DRA WSELECT commands, then 

tag them appropriately. 

Several techniques can be used for tagging polygons, 

and selecting the most efficient technique requires some 

planning. The TAG subroutine method is not the most 

efficient one for all coverages. If a map has many polygons 

but only a few map units, the preferred technique may be to 

select all the label points, calculate them to the value of the 

most common map unit, and then interactively retag those 

polygons that should have different values. Conversely, 

some maps contain a large number of map units (for 

example, 20 or more), and no single map unit accounts for 

a predominant number of the polygons. For such a coverage, a field of view may contain only one or two label 

points for any given map unit; it may, therefore,be faster to 

interactively select each label point and calculate the proper 

item value than to use the TAG menu. For other coverages, 

many label points of the same map unit may be clustered in 

part of the map. The efficient tagging method there may be 

to use the SELECT BOX command to select all label points 

within an area, calculate them all to the value for the most 

common map unit, and then interactively select and recalculate those label points that should have different item 

values. 

F-5. Assigning Item Values to Arcs on the basis of Polygon 

Item Values 

In many coverages, arcs must be assigned attribute 

information that is dependent on polygon information (for 

example, contour values or type of geologic contact). These 

arc items can be tagged automatically by relating the .AAT 

F-5. Assigning Item Values to Arcs on the basis of Polygon Item Values 25 
to the . PAT and by selecting and calculating item values as 

shown in the two examples below. 

Arc: INFO 

ENTER COMMAND> SEL <coverage>.AAT 

Establish the relate environment: 

ENTER COMMAND> RELATE 1 

<coverage>.PAT BY LPOLY# LINK RO 

ENTER COMMAND> RELATE 2 

<coverage>.PAT BY RPOLY# LINK RO 

Example 1: Identify geologic contacts. Select lines 

separated by polygons having different values for 

the geologic unit item (itemname). Then, calculate 

a value that will designate those arcs as geologic 

contacts (calculate for item GEOLCONTACT). 

ENTER COMMAND> RES $1 <itemname> NE 

$2<itemname> 

ENTER COMMAND> CALC GEOLCONTACT = 1 

Example 2: Thickness contour lines can be tagged 

by selecting those lines that lie between polygons 

having different thickness values. In this example, 

MINOR1 is the .PAT item for thickness values. 

Values for MINOR1 represent different thickness 

intervals (for example, where MINOR1 = 1, the 

thickness interval is 0-50 ft, and where MINOR1 

= 2, the thickness interval is 50-100ft). 

ENTER COMMAND> ASEL 

ENTER COMMAND> RES ( $1 MINOR1 = 1 AND 

$2MINOR1 = 2 ) OR ( $1 MINOR1 = 2 AND 

$2MINOR1 = 1 ) 

ENTER COMMAND> CALC THICKCONTOUR = 50 

F-6. Checking for Tagging Errors 

Although errors may be detected in ARCEDIT by 

selecting for the different label values and drawing each in 

a different color, it is generally much more efficient to use 

ARCPLOT to check for errors because ARCPLOT has 

polygon-fill capability. An AML may be executed that will 

draw the coverage and fill the polygons in selected colors. 

Execute the AML, here named "PLOT.AML," as follows: 

Arc: &RUN PLOT.AML 

NOTE: The ".AML" suffix can be omitted from the 

command. This AML contains the following commands: 

ARC PLOT 

MAPEXTENT <coverage> 

SHADESET <shadesetname> (this command is 

optional) 

POL YGONSHADES <coverage> <item> 

<lookup table (optional argument)> 

ARCS <coverage> 

&RETURN 

The AML will execute the ARCPLOT commands to 

the terminal; the polygons will be shaded with colors and 

(or) patterns, and arcs will be drawn. These commands 

could also be issued interactively; if this is done, omit the 

&RETURN command. If a SHADESET is not specified, 

then the default shadeset will be used. In the POLYGONSHADES command, the values for the specified .PAT item 

are used as the shade symbol numbers to fill the polygons. 

This approach may not produce the desired result, commonly because, when the item values were assigned, the 

values were determined by some criteria other than to 

correspond to shadeset values that would produce the 

desired range of colors and patterns on the screen. Using the 

item values as shade symbol numbers can also cause 

problems if any of the values are outside the range of the 

shadeset. A color lookup table and, for some maps, a 

customized shadeset would improve plot legibility. The 

lookup table, explained in more detail below, specifies a 

shade symbol number for each item value. 

An ARCPLOT screen display provides a good 

method for rapidly detecting errors. However, the final 

inspection of the map is commonly done on full-size 

hardcopy plots. To obtain a plot, generate a plotfile in 

ARCPLOT and execute the plotfile on a hardcopy device; 

we used an electrostatic plotter. An AML to execute the 

commands and create the plotfile is shown below: 

ARC PLOT 

DISPLAY 1039,2 

<plotfilename (for example, #PLOT)> 

SHADESET <shadesetname for plotter 

device> 

MAPEXTENT <coverage> 

MAPUNITS <units (for example, METERS)> 

MAPSCALE <(for example, 1000000 for 

1:1,000, 000-scale output)> 

POL YGONSHADES <coverage> <item> 

<lookup table (optional argument)> 

ARCLINES <coverage> <item> <lookup table 

(optional argument)> 

QUIT 

&RETURN 

This AML is executed in the same way as PLOT.AML. As 

a default, colors and patterns for polygon interiors and arcs 

are determined by values for the specified item; those values 

are used as the hardware colors in the SHADESET file or 

line types in the LINESET file. For this AML, the default 

lineset (PLOTTER.LIN) is used and is, therefore, not 

specified. If a lookup table is specified as an argument to 

POLYGONSHADES or ARCLINES, then item values are 

related to selected hardware colors or line types listed in the 

lookup table. Lookup tables are extremely useful for customizing output, and they can be updated to change a plot's 

appearance. A lookup table can be created in INFO as 

follows: 

ENTER COMMAND> DEFINE <lookup table 

name (for example, LOOKUP. TAB)> 

26 A User's Manual for a Method of Map Scanning and Digital Editing 
Item name,width [,output width] ,type [,decimal 

places] [,protection level] 

NOTE: When specifying format in the following dialog, use "4 5 B" for "coverage item name" and 

for "symbol" and ensure that, in the attribute 

table, "coverage item name" has this format. 

1 

ITEM NAME> <coverage item name 

(for example, COLOR)> 

ITEM WIDTH> 4 

ITEM OUTPUT WIDTH> 5 

ITEM TYPE> 8 

5 

ITEM NAME> SYMBOL 

ITEM WIDTH> 4 

ITEM OUTPUT WIDTH> 5 

ITEM TYPE> B 

9 

ITEM NAME> <cr> 

ENTER COMMAND> ADD 

NOTE: Always set COLOR and SYMBOL to 0 (zero) 

for the first record of the file. 

1 

COLOR> 0 

SYMBOL> 0 

2 

COLOR> 1 

SYMBOL> 16 

3 

..... . etc ...... . 

4 

COLOR> <cr> 

ENTER COMMAND> L1 

$RECNO COLOR SYMBOL 

1 0 0 

2 1 16 

3 ..... . etc ..... . 

ENTER COMMAND> Q STOP 

The lookup table, LOOKUP.TAB, will use the values for 

item name COLOR to assign hardware shadeset values in 

SYMBOL. The item name must be specified as an argument to the POL YGONSHADES or ARCLINES command. 

To change values in the lookup table, use the UPDATE 

command in INFO. If an item name must be changed after 

the lookup table has been created, then use the ALTER 

command (see section F-7). 

A particular lookup table may be useful for plotting 

coverages located in different directories. Rather than 

creating an identical lookup table in INFO in each of the 

other directories, attach to the destination directory, invoke 

INFO, and copy the lookup table from the source directory 

as follows: 

ENTER COMMAND> ADIR <full pathname 

to source directory (for example, 

DRSOLLER>MT>INFO)> 

ENJER COMMAND> TAKE DATA ARC <file 

name (for example, LOOKUP. TAB)> 

F-7. Combining Coverages and Eliminating Sliver Polygons 

This report is confined mostly to discussion of essential, basic techniques. However, the more specialized technique of combining several polygon coverages was required 

for processing our test map and may be of general interest. 

ARC has three commands that perform this operation under 

different rules: UNION, IDENTITY, and INTERSECT. 

Consult the ARC/INFO user's manual (volume 2) for 

details. 

For the test map, separates showing the character of 

surficial deposits and the thickness of Quaternary sediments 

had to be combined into a coverage that contained all arcs 

of the two coverages. Therefore, the UNION command was 

generally used. This procedure merges the map data and 

attribute tables from two coverages. Because our procedure 

involves the use of the ELIMINATE command after 

UNION, we found it prudent to combine the separates 

before tagging arcs according to the procedures outlined in 

section F-5. ELIMINATE can remove polygon label points 

and certain arcs that describe spurious polygons generated 

during UNION; item values for arcs can, therefore, be 

affected by this command. 

For some of our larger coverages, the UNION operation failed after encountering an arc intersection during the 

polygon-building phase of the operation. When UNION 

fails, the error message provides the intersection coordinates so that it can be corrected in ARCEDIT. To correct 

the error, invoke ARCED IT and specify one coverage as the 

EDITCOVERAGE and the other as the BACKCOVERAGE. Specify DRAWENVIRONMENT ARC, NODE, 

LABEL and BACKENVIRONMENT ARC, NODE, 

LABEL. Do not draw the coverage yet, as drawing is 

unnecessary and time consuming. On the blank screen, find 

the approximate location of the arc intersection with the 

WHERE command (if the EDITl.AML is being used, 

select "ARCEDIT command," then WHERE). Select 

MAPEXTENT * and define the box to include the intersection coordinates. Next, draw the coverage. Set parameters 

such as EDITDIST ANCE (see section F-1) and locate the 

arc intersection coordinates with the WHERE command. If 

the problem lies in the EDITCOVERAGE, move the arcs as 

needed to prevent the UNION operation from failing again. 

If the problem lies in the BACKCOVERAGE, redefine the 

backcoverage as the new editcoverage and correct the 

problem. Save and quit ARCED IT, BUILD the edited 

coverage, and retry the UNION operation. As a precaution 

against unexpected problems with polygon or arc attribute 

tables, perform the INFO update and !DEDIT procedure 

(see section F-3) on the rebuilt coverage before executing 

the UNION command. 

On the second try, UNION may fail again after 

encountering another arc intersection. For our map project, 

the iterative process of editing the coverages and rerunning 

the UNION operation was lengthy: a successful UNION 

operation required, on some coverages, as many as 6 hours 

F-7. Combining Coverages and Eliminating Sliver Polygons 27 
to complete in batch mode. Large coverages that fail to be 

combined with UNION may be combined by using the 

INTERSECT command. INTERSECT performs the same 

type of operation as UNION, but it involves only the area in 

common between the two coverages. For our coverages, 

this was not a significant limitation, as both coverages were 

of the same size and had nearly identical neatline positions. 

In the UNION and INTERSECT operations, attribute 

tables from the two coverages are compared and combined 

into a new attribute table. For identical items in the two 

coverages (for example, MINOR!), the item value for the 

INTERSECTCOVER or UNIONCOVER (see below) is 

placed into the new attribute table, and the item value for 

the other coverage is discarded. It may be desirable to retain 

certain items named the same in both source coverages, 

such as items that identify the type of geologic unit. If so, 

before executing the UNION or INTERSECT operation, 

change the item name(s) in one of the coverages, by using 

the ALTER command in INFO: 

ENTER COMMAND> SEL <coverage.PAT or 

coverage.AAT> 

ENTER COMMAND> IT (item names and formats 

will be listed) 

ENTER COMMAND> ALTER 

ITEM NAME> <item> 

ITEM NAME> <new item name> 

NOTE: After the item name(s) is (are) changed, the 

control-A escape sequence can be used to return 

the user to the INFO prompt. It is not necessary 

to change the item output width or other components of item format. 

ITEM OUTPUT WIDTH> <control-A> 

ENTER COMMAND> Q STOP 

If the item format needs to be changed for some 

reason, the safest, and therefore probably the best, procedure is to add a new item having the desired format, 

calculate the values for the old item into the new item, and 

drop the old item from the attribute table. 

After the attribute tables are checked, the UNION or 

INTERSECT command can be issued. The first three 

arguments of these commands are required: INCOVERAGE and UNIONCOVERAGE or INTERSECTCOVERAGE are combined to form OUTCOVERAGE. The fuzzy 

tolerance argument sets the minimum distance allowed 

between arc coordinates (that is, the map resolution) and 

need not be specified if the default value is acceptable. For 

coverages similar to the test map, the ARC/INFO rule for 

calculating the default fuzzy tolerance is (width of the 

BND)/10,000. Default tolerances for the map coverages 

were roughly 5 m. Considering that the map was compiled, 

and will be published, at 1:1,000,000 scale, we judged this 

level of resolution to be unnecessarily high. We selected a 

50-m tolerance as a compromise between resolution and 

computer processing time. The last argument, JOIN or 

NOJOIN, specifies whether all items from both .PATs will 

be combined into the OUTCOVERAGE.PAT. We used 

JOIN, which is the default. For INTERSECT, the type of 

output coverage (POLY, LINE, or POINT) is specified in 

the fourth argument. We used POLY, which is the default. 

As will be noted by comparison of the following 

dialog with examples given in the ARC/INFO manual, no 

input is required if the default value for an argument is 

chosen, unless it is followed by an argument for which the 

default value is not chosen. Then,# must be used to specify 

the default value. 

Finally, the BUILD command must be issued to 

restore proper polygon topology. Because an .AAT is not 

created for the outcoverage, BUILD with the LINE option 

must also be used if an .AAT is desired. 

Arc: To guard against problems resulting from 

ARCEDIT and INFO processing of a source coverage prior to UNION or INTERSECT, it may be 

appropriate to execute the INFO update and 

/DEDIT procedure outlined in section F-3. 

Arc: UNION <incoverage> 

<unioncoverage> <outcoverage> 

<fuzzy tolerance (for example, 50)> 

..... . or ..... . 

Arc: INTERSECT <incoverage> 

<intersectcoverage> <outcoverage> 

# <fuzzy tolerance (for example, 50)> 

NOTE: The computer issues processing statements 

that require no response. 

Arc: BUILD <outcoverage> LINE (if an .AAT is 

desired) 

Arc: BUILD <outcoverage> 

The .PAT of the combined coverage contains polygon internal number and -ID number items for both source 

coverages. In many cases, these items are no longer needed. 

Inspect the .PAT in INFO after executing the BUILD, and 

note the unneeded items. Quit INFO and drop those items. 

UNION and INTERSECT cause the two coverages to 

be overlain and combined, forming many new polygons. 

Some of these polygons may be spurious artifacts of the 

process and should be deleted. Generally, these spurious 

polygons are narrow and small and are termed "sliver 

polygons." They are especially common where the source 

coverages contain lines in nearly the same position. For 

example, geologic contacts along the borders of a stream 

valley might be subparallel to, and in places coincide with, 

sediment thickness contours within the valley. When the 

geology and thickness coverages are combined, sliver 

polygons may be produced along the valley margins. 

By nature, sliver polygons generally have small 

area-to-perimeter ratios. However, there is commonly a 

gradation, as well as some degree of overlap, between the 

population of sliver polygons and the population of polygons that are valid and should be retained. To eliminate 

28 A User's Manual for a Method of Map Scanning and Digital Editing 
sliver polygons, an area/perimeter ratio must be selected 

that isolates most sliver polygons from the general polygon 

population. For this optimum ratio, some of the smallest 

valid polygons may fall within the sliver polygon population, but that is unavoidable and generally of little consequence. The optimum ratio is best selected visually, perhaps by using the following technique: 

Arc: ADDITEM <coverage>.PAT 

<coverage>.PAT RATIO <format 

(for example, 4 12 F 3)> 

Arc: INFO 

ENTER COMMAND> SEL <coverage>.PAT 

ENTER COMMAND> CALCULATE RATIO= 

AREA I PERIMETER 

ENTER COMMAND> Q STOP 

Arc: ARCPLOT 

ARCPLOT: MAPEXTENT <coverage> 

ARCPLOT: ARCS <coverage> 

ARCPLOT: SHADESET <shadesetname> 

(if default is not acceptable) 

ARCPLOT: ASEL <coverage> POLY 

ARCPLOT: RESEL <coverage> POLY RATIO 

< 50 (or some other value) 

ARCPLOT: POL YGONSHADES <coverage> 2 

(polygons for which RA T/0 is <50 are filled with 

the shadeset's color 2) 

ARC PLOT: NSEL <coverage> POLY 

ARCPLOT: RESEL <coverage> POLY RATIO 

< 60 

ARCPLOT: POL YGONSHADES <coverage> 3 

ARC PLOT: ASEL <coverage> POLY 

ARCPLOT: RESEL <coverage> POLY RATIO 

< 60 

ARC PLOT: NSEL <coverage> POLY 

ARCPLOT: RESEL <coverage> POLY RATIO 

< 70 

ARC PLOT: POL YGONSHADES <coverage> 4 

ARCPLOT: ASEL <coverage> POLY 

..... . etc ..... . 

This technique allows the user to interactively display 

polygons having different area/perimeter ratios and to select 

the most appropriate ratio. For some maps, the user may 

need to clear the screen, redraw the arcs, and then select and 

draw polygons by using a range of ratios different from that 

used in the first trial. 

Sliver polygons are eliminated with the ELIMINATE 

command. In the following example, we assume that 

"RATIO = 60" is the optimum choice: 

Arc: ELIMINATE <coverage> <outcoverage> 

NOTE: The computer issues processing statements 

that require no response. 

>: RES RATIO < 60 

>: <cr> 

Do you wish to re-enter expression (Y/N)? N 

Do you wish to enter another expression (Y /N)? N 

1406 features out of 8530 selected. 

Number of Polygons (lnput,Output) = 8530 7209 

Number of Arcs (lnput,Output) = 19111 17780 

Creating OUTCOVERAGE.PAT 

Arc: BUILD <outcoverage> 

Arc: perform INFO update and /DEDIT (see section 

F-3) 

F-8. Unsplitting Arcs 

Certain coverages may contain many pseudonodes, 

which may be detected with ARCED IT's DRA WENVIRONMENT NODE or DRA WENVIRONMENT NODE 

PSEUDO option. This variety of node separates but two 

arcs. Pseudonodes are used to separate arcs that contain 

more than 500 coordinates, which is the maximum number 

of coordinates, or vertices, per arc allowed by ARC/INFO. 

Pseudonodes can also be generated by other procedures in ARC/INFO, such as extensive editing of arcs or 

using the ELIMINATE command to remove sliver polygons. In these cases, a single arc could replace two or more 

arcs separated by pseudonodes. If sliver polygons have been 

removed with the ELIMINATE command, or if extensive 

editing has produced many pseudonodes, we recommend 

that pseudonodes be removed with the UNSPLIT command. This command may significantly reduce the file size 

and, hence, plotting and processing time. The UNSPLIT 

command removes pseudonodes between arcs having the 

same "<coverage>-ID" number. Therefore, before unsplitting, the <coverage>-ID numbers must be recalculated. 

After the unsplit operation, the coverage's topology must be 

rebuilt. If arcs have been tagged interactively to identify a 

certain attribute (for example, type of geologic contact), 

then UNSPLIT should be performed only before arc tagging, because when UNSPLIT removes a pseudonode and 

combines two arcs, item values for one arc are retained and 

values for the other arc are discarded. If, however, arcs are 

tagged automatically, as discussed in section F-5, 

UNSPLIT can be performed at any time and can be 

followed by arc retagging. 

When executed on a large file containing many 

pseudonodes, the UNSPLIT command may require several 

hours, or even days, to complete. It may be most efficient 

to perform this operation from an AML (UNSPLIT.AML 

shown below) executed in batch mode. 

Arc: &R UNSPLIT 

This AML could consist of the following commands: 

ARCEDIT 

EDITCOVERAGE <coverage> 

EDITFEATURE ARC 

GRAPHICS OFF 

SNAPDISTANCE 0 

NOTE: In the following example, all arcs in the coverage are selected for unsplitting. Unsplitting can 

also be performed on a selected subset of arcs. 

To do so, use the SELECT FOR command. 

SELECT ALL 

F-8. Unsplitting Arcs 29 
CALC <coverage>-10 = 99 (or some other unique 

value) 

UNSPLIT 

SAVE 

QUIT 

&RETURN 

NOTE: After the AML has executed, rebuild the coverage, and perform the INFO update and /DEDIT 

(see section F-3). 

This procedure can also be run interactively, although 

that would be most appropriate only for coverages of 

relatively small file size. To do so, specify the display and 

terminal device number (see section D), enter ARCEDIT, 

and execute all the above commands except &RETURN. 

G. Generating Color Separates for Map Printing 

Before the user begins to create color separates, each 

coverage should be fully edited. Next, each coverage must 

be converted to the proper format for the device that will 

generate the color separates. For our purposes, the Scitex 

Response-280 editing workstation and plotter are the 

devices of choice because they can process large-format 

maps and can produce high-quality printing screens. This 

section covers ARC/INFO's format conversion commands, 

a brief overview of processing procedures used by the 

Scitex Response-280 system, and ARC-to-DLG format 

conversion. The discussion is not sufficiently detailed to be 

a user's manual for the Scitex; instead, it is a general 

introduction to Scitex map-processing procedures. 

G-1. Converting Map Data from ARC/INFO to Scitex 

Format 

ARC/INFO coverages can be converted into Scitex 

Response-280 format files by the ARCSCITEX command 

and by the PLOTSCITEX command. ARCSCITEX converts one or more ARC/INFO coverages to Scitex format. 

PLOTSCITEX converts an ARCPLOT plotfile generated 

from a coverage or group of coverages. The two commands 

provide different approaches to map preparation but can 

produce the same map product. The appropriate command 

should be chosen after consultation with Scitex personnel. 

We chose to convert the coverages with ARCSCITEX. Many conversion parameters can be specified in 

ARCSCITEX; the following dialog shows the basic commands we used to convert our map coverages: 

Arc: ARCSCITEX <desired prefix for all Scitexformat output files (for example, GEOL)> 

Arcscitex: COVERAGE <coverage name> 

<LINE> 

Arcscitex: LINEFONT <item> 

NOTE: Values for the item specified in the 

LINEFONT command are passed to Scitex in the 

DIGIT file with line coordinate information. The 

item values may range from 1 to 999. The EXECUTE command clears the current LINEFONT 

command. 

Arcscitex: STATUS (use if desired to check the status of all conversion arguments) 

Arcscitex: PAGESIZE <width> <height> 

NOTE: We used a page size slightly larger than the 

anticipated map dimensions at our specified map 

scale. Specify page size in inches (the default 

unit); if another unit of measure is desired, specify 

it with the PAGEUNITS command. 

Arcscitex: MAPSCALE <(for example, 1000000 for 

1:1 ,000,000-scale output)> 

Arcscitex: MAPEXTENT <coverage name> 

Arcscitex: RESOLUTION <rasters or pixels per 

millimeter (for example, 17)> 

Arcscitex: EXECUTE 

Conversion of Line coverage "COVERAGE NAME" 

completed. 

Arcscitex: COVERAGE <coverage name> 

<POLY> 

Arcscitex: AREAFONT <item> 

NOTE: Values for the item specified in the 

AREAFONT command are passed to Scitex in the 

TEXTEDIT or ARF file (area reference file) with 

the coordinates of label points for polygons and 

are used to assign colors and (or) patterns (areafill fonts) for Scitex area filling. For most map 

applications, the item values represent different 

map units or color screen values. Values must 

correspond to available Scitex color channels 

(1-12), or they must be converted to Scitex color 

channel values by means of the RELATE command and a lookup table. The EXECUTE command clears the current AREAFONT command. 

Arcscitex: EXECUTE 

Conversion of Polygon coverage "COVERAGE 

NAME" completed. 

Arcscitex: QUIT 

Creating ARF files for each partition ... 

Sorting DIGIT attributes .. . 

Generating output report .. . 

Leaving ARCSCITEX ... 

Arc: 

In the above dialog, three files were generated by 

ARCSCITEX. The first, initiated by the COVERAGE 

command with the LINE option, is a Scitex DIGIT file, 

GEOL.DIG, containing the linework; the suffix .DIG refers 

to a DIGIT file. In Scitex operations, DIGIT files are 

labeled as type 310 files. The second file, initiated by the 

COVERAGE command with the POLY option, is a Scitex 

TEXTEDIT or ARF file, GEOL_DEFAULT.ARF, containing the label points; the suffix .ARF refers to a Scitex 

area reference file. In Scitex, TEXTEDIT files are referred 

to as type 102. For each ARC/INFO label point, the 

TEXTEDIT file contains a pair of x- andy-coordinates and 

a color channel or pattern name (for example, 1375,2932,5 

or 1375,2932,pattern name) determined by the item speci30 A User's Manual for a Method of Map Scanning and Digital Editing 
fied in ARCSCITEX. The third file is an output report 

(GEOL.RPT). 

On the Scitex, many thematic maps are plotted at a 

resolution of 17 rasters, or pixels, per millimeter, also 

referred to as RES 17. This setting provides a good compromise between file size and resolution and captures line 

positions with an accuracy equal to that of conventional 

trace scribing. For color on thematic maps, the USGS uses 

RES34 screens as its standards. Screens of lower resolution 

produce a noticeably lower quality image. For thematic 

maps processed at RES 17, screens can be plotted at RES34 

by specifying 2 in response to the dialog prompt for the 

number of screen elements per pattern element. The Scitex 

SCREENLIB command allows storage in a disk library of 

as many as six screens. Commonly, four screens are 

required (yellow, magenta, cyan, and black), and they are 

set at angles of 90, 15, 75, and 45 degrees, respectively. 

The Scitex has 12 color channels; commonly 1 

channel is reserved for the linework, 1 is reserved for the 

background color, and 10 channels are assignable to mapunit colors. A TEXTEDIT file, therefore, can contain only 

10 different map units to be filled with color. If a coverage 

contains more than 10 map units, then more than one 

TEXTEDIT file is required. The part of the Quaternary 

sediments map scanned for testing our method contains 

more than 10 map units; they belong to four thematic 

categories or groups, each having fewer than 10 different 

units. Therefore, the coverage to be output to Scitex was 

copied four times. Values for the geologic unit item in the 

. PAT were modified for each new coverage to create four 

different polygon coverages, one for each group of map 

units. Because the first of the new coverages will show label 

point information only for polygons of the first group, the 

geologic unit item for all other label points was recalculated 

to zero. The polygons in the first group were recalculated to 

values between 1 and 10, in order to correspond to the 

Scitex color channels. This procedure was applied to the 

other three coverages. In the ARCSCITEX subroutine, the 

COVERAGE command with the LINE option was executed 

once, and then the four new coverages were each executed 

with the POLY option. This processing could be done as 

follows: 

NOTE: For this example, a coverage named "GEOL" 

has more than 10 map units, naturally divisible 

into four thematic categories or groups, each having fewer than 10 different map units. The item 

containing the map unit identifier is GEOLOGY; 

item values range from 101 to 108 (group 1), from 

201 to 208 (group 2), from 301 to 308 (group 3), 

and from 401 to 408 (group 4). To format the coverage tor the Scitex, copy the coverage four 

times, invoke INFO and select the first new coverage, set the GEOLOGY item values tor groups 2 

to 4 to zero, perform an NSEL to reselect group 

1, and recalculate the group 1 item values so that 

values range from 1 to 10 (or Jess). 

Arc: COPY GEOL GEOL 1 (then repeat for GEOL2, 

GEOL3, GEOL4) 

Arc: INFO 

ENTER COMMAND> SEL GEOL1.PAT 

ENTER COMMAND> RES GEOLOGY LT 101 OR 

GEOLOGY GT 108 

ENTER COMMAND> CALC GEOLOGY = 0 

ENTER COMMAND> NSEL 

ENTER COMMAND> CALC GEOLOGY = GEOLOGY - 100 

NOTE: Perform similar calculation on other coverages, resulting in four coverages created from the 

source coverage, each having GEOLOGY item 

values ranging from 1 to 10 for only one map 

group. 

ENTER COMMAND> Q STOP 

Arc: ARCSCITEX <desired prefix for all Scitexformat output files (for example, GEOL)> 

Arcscitex: COVERAGE GEOL LINE 

Arcscitex: LINEFONT <item> 

Arcscitex: PAGESIZE <width> <height> 

Arcscitex: MAPSCALE <scale> 

Arcscitex: MAPEXTENT GEOL 

Arcscitex: RESOLUTION <(for example, 17)> 

Arcscitex: EXECUTE 

Arcscitex: COVERAGE GEOL 1 POLY 

Arcscitex: AREAFONT GEOLOGY 

Arcscitex: EXECUTE 

Arcscitex: COVERAGE GEOL2 POLY 

Arcscitex: AREAFONT GEOLOGY 

Arcscitex: EXECUTE 

.. . Repeat for each coverage ... 

Arcscitex: QUIT 

Arc: 

The four TEXTEDIT files created from the test map 

must later be processed on the Scitex into color separate 

files in order to generate the color screens. Because the 

Scitex is configured as a single-user system, any processing, whether interactive or in batch mode, prevents the 

Scitex editing workstation from being used for other purposes. More map projects could be processed with greater 

efficiency if the processing into color separate files were 

done on the ARC/INFO coverages before conversion to 

Scitex format; computers that run ARC/INFO are more 

common than Scitex editing workstations and can more 

readily accommodate the extra processing task. Scitex 

represents a data-processing bottleneck, is a system not 

readily accessible or usable by most thematic map project 

personnel, and may entail significant processing-related 

expenses. It may, therefore, be desirable to add items to the 

.PAT in ARC/INFO for each of the color channels and to 

calculate the proper screen values into each color channel 

item. This procedure is easily performed in an AML. In the 

following example, information on the geologic map units 

is contained in the item MINOR3. MINOR3 values of 

101-110, 201-210, 301-310, and so on, are categories of 

genetically related map units. Map units in a category have 

similar colors and are treated as a group in the AML. 

G-1. Converting Map Data from ARC/INFO to Scitex Format 31 
Arc: ADDITEM <coverage>.PAT 

<coverage>.PAT (! <items for color 

separates (for example, YELL,RED,CYAN, 

BLK,BRN)> !) <format (for example, 

4 5 B)> 

Arc: &R COLORSEP.AML 

NOTE: The COLORSEP.AML could contain the commands and logic shown below: 

&DATA ARC INFO 

SEL <COVERAGE>.PAT 

CALC YELL= 0 

CALC RED= 0 

CALC CYAN= 0 

CALC BLK = 0 

CALC BRN = 0 

RES MINOR3 GE 101 AND MINOR3 LT 200 

CALC YELL= 7 

CALC RED= 1 

CALC CYAN= 1 

CALC BLK = 1 

CALC BRN = 1 

RES MINOR3 GT 101 

CALC YELL = 10 

CALC RED= 11 

RES MINOR3 GT 102 

CALC RED= 3 

RES MINOR3 GT 103 

CALC RED= 6 

RES MINOR3 GT 104 

CALC YELL= 5 

CALC RED= 10 

ASEL 

RES MINOR3 GE 201 AND MINOR3 L T 300 

... Follow the logic shown above to identify other 

appropriate color values . .. 

Q STOP 

&END 

&RETURN 

However, passing screen values, rather than map-unit 

values, to Scitex does have a drawback: the color separate 

files (discussed below) cannot be used to check for multiple 

definitions (multiple label points in a polygon) or for 

unfilled areas of a polygon separated from the label point by 

a narrow area, or bottleneck. A multiple definition commonly points to an error in the data set or to a label point 

that, upon conversion to Scitex, no longer falls within the 

bounds of the polygon. For many maps, this check for 

multiple definitions may not be a serious loss because errors 

can be detected in the color proof. 

For maps with many narrow polygons and unfilled 

areas, this procedure may be inappropriate; the time needed 

to fill the areas with color for each color separate may be far 

greater than the time needed to process a coverage into color 

separates by using the COMBSEP command and PLACR 

batch command (see section G-3). However, for such 

maps, the number of unfilled areas can be greatly reduced, 

and the use of this procedure justified, by executing the 

ARCSCITEX command with a high resolution (for example, RES34 as discussed in section G-3). The high resolution will produce smaller pixels upon execution of the 

DIGIT file to a 1-pixel-width line file and will, therefore, 

produce fewer bottlenecks and unfilled areas. 

G-2. Transferring the Scitex-Format Files from ARC/INFO 

to Scitex 

ARC/INFO's SCITEXWRITE command was used to 

write the files to magnetic tape in a format that can be read 

by a Scitex Response-280 editing workstation. The SIF 

(standard interchange format) option should not be used. 

The tape is read onto the Scitex with the TCOPY command. 

Proper responses to TCOPY prompts are as follows: 

ENTER FILE LIST: <filename>: <file type (enter 

310 for a DIGIT file, 102 for a TEXTEDIT file)> 

FILE BLOCK FORMAT: FIX 

SWAP BYTES: NO 

G-3. Scitex Processing to Produce Color Separates 

The Scitex DIGIT and TEXTEDIT files must be 

processed to produce color- and (or) pattern-filled polygons. After the user has checked for completeness and 

quality of the color fill, the files can be processed into files 

that each contain the patterns or screen percentage information required for the Scitex to plot each color separate. 

Before the polygons are filled with color, the DIGIT file, 

also known as the "color boundary file," must be rasterized 

so that lines are 1 pixel wide; use the DIGIT command with 

the EXC or VTR (vector-to-raster) option. We first tried 

this at RES 17, but, because our linework is tightly spaced, 

some of the lines were not properly positioned for a 

successful polygon-fill operation. We executed (rasterized) 

the DIGIT file again at RES34, which rectified most of the 

polygon-fill errors. The rasterized line file should then be 

checked for line breaks with the FINDEP (find endpoint) 

command, which finds endpoints of single-pixel-width 

lines. Line breaks can be closed interactively. 

Before proceeding further, the user should check the 

rasterized line file for proper scaling and registration. The 

line file must be at the same scale as the base map with 

which it will be combined for printing, and it should register 

to all other files (for example, color-fill files) used to print 

the map. Because the Tektronix scanner and the Scitex 

plotter may differ in their calibration, it is advisable to 

check for proper scaling of Tektronix-scanned files (and for 

Scitex-scanned files as well, unless the scanner and plotter 

are calibrated precisely the same). Manipulation of data in 

ARC/INFO (for example, by the PROJECT or TRANSFORM commands) may also change map dimensions sufficiently that rescaling is required before the scanned map 

will fit the base map. To facilitate rescaling, ensure that all 

ARC/INFO coverages contain some registration marks as 

32 A User's Manual for a Method of Map Scanning and Digital Editing 
arc features (such as the neatline, registration marks outside 

the map area, or a shoreline shared by the base map and all 

coverages), unless rescaling will be checked by registration 

to the author's inked linework on the base map. 

To check for proper scaling, compare a Scitexgenerated clear film plot of the line file to a scale-stable 

copy of the base map or to a scale-stable copy of the 

author's linework that registers to the base map. If the plot 

does not register precisely to the author's linework or to the 

base map, then the required increase or decrease in both the 

x- and y-dimensions should be measured to the nearest 

thousandth of a millimeter. Dimensions must be measured 

in inches, unless another unit of measure was specified in 

ARCSCITEX. 

When the proper x- andy-dimensions are known, the 

line file can be rescaled by using either of two approaches. 

Because the physical size of the line plot is governed by the 

size of the blank pattern upon which Scitex places the raster 

line image, the most accurate method of resizing the line 

file is by creating a new blank pattern of the proper 

dimensions. Then, use the DIGIT command to create a new 

raster line file from the DIGIT file; the new line file will be 

sized in accordance with the new blank pattern. A similar 

result can be obtained by merely rescaling the line file when 

plotting. This rescaling may produce lines of slightly lower 

quality, although they may still be accurate enough for 

many applications. Using either method, create a plot of the 

raster line file with the x- and y-dimensions adjusted, and 

check the plot against the base map. Rescale as needed. If 

all coverages were registered properly in ARC/INFO, these 

scaling factors should suffice for all files. The TEXTEDIT 

files cannot, however, be rescaled. Color-fill files generated 

from a TEXTEDIT file can be rescaled during plotting by 

using the scaling factors for the newly sized blank pattern. 

The polygons are filled by colors and (or) patterns by 

the ARF (area reference file) command. This command 

associates the edited, 1-pixel-wide lines of the raster line 

file created from the DIGIT file with a TEXTEDIT file and 

uses the lines as boundaries between colors or patterns. A 

point of color or pattern is placed at the coordinate pair 

location and is then repeated in all directions until stopped 

by the 1-pixel-wide line. Multiple definitions are identified 

by the ARF command and can be corrected. Because we 

had four TEXTEDIT files, we executed ARF four times in 

batch mode with the USGS-written FILLR batch command. 

The polygon-fill files created by the ARF or FILLR 

command should be overlain to check for errors: some 

polygons may be without a coordinate pair (an ARC/INFO 

label point) and, hence, are not filled, or polygons may 

have more than one coordinate pair (a multiple definition) 

and, hence, are filled with the wrong color. As noted above, 

if color screen values are passed to Scitex rather than values 

representing the map unit, this discussion is not applicable; 

errors must be checked in the color proofs. A USGS-written 

batch command, PLACR, checks for these problems. This 

batch should be run on copies of the color-fill files because 

it overwrites the color values for each raster location. 

PLACR writes the first file to the Scitex work area 

and assigns channel 1 to all raster locations within the 

polygons that were color filled. For areas not to be filled, 

rasters are assigned channel 12 (background). Next, all 

raster locations in the second file that should be colored 

(that is, that occur in color-filled polygons) are assigned 

to channel 2. File 2 is digitally compared with file 1, and 

rasters in channel 2 are changed to channel 3 if they 

coincide with rasters in file 1 colored by channel 1. 

All raster locations in file 2 coinciding with rasters not 

to be plotted in file 1 (background, or color channel 12) 

are reassigned to channel 1. File 3 and subsequent files 

are modified by the procedures used to modify file 2. If 

file 3 contains a colored raster that coincides with a colored 

raster of files 1 or 2, then the file 3 rasters are reassigned, 

not to channel 3, but to channel 4. If this error occurs 

in subsequent files, the channel assignment increases 

accordingly. 

To detect areas unfilled by any of the files, paint the 

map margin with a nonbackground color; this PLACR 

option is performed after all files are placed together so that 

unfilled areas can be found by searching for the background 

color inside the map. To find the unfilled areas, run the 

NODES command to search for channell2, the background 

color. Unfilled areas may result from incorrect color channel values or from constricted polygons. Scitex fills a 

polygon with color by starting at the coordinate pair and 

filling outward in all directions; lines may be so tightly 

spaced that they inhibit filling of the entire polygon. That 

part of a polygon beyond the constriction will, therefore, 

remain unfilled. For our test map, very few multiple 

definitions or unfilled polygons were encountered. 

After identifying an unfilled map area, add coordinates and the appropriate color channel value for a single 

point to the corresponding TEXTEDIT file or interactively 

fill the polygon on the Scitex. For some constricted polygons, it may also be wise to update the ARC/INFO 

coverage by dividing the polygon at the constriction and 

forming two polygons having identical attributes. For the 

intervening line, the "line type" item in the .AAT should be 

coded such that, if passed with the DIGIT file by the 

LINEFONT command at some time in the future, it will not 

be plotted on the Scitex (see discussion of Font Library 

below). Updating the ARC/INFO coverage to remedy the 

color-fill problems detected on the Scitex might prove 

helpful for workers who intend to update their map data 

base and print revised versions. 

After all colors and patterns have been placed correctly, the proper Scitex output color codes should be 

placed into a batch file. Color separate files are then 

produced from the ARF-generated files, one color separate 

file for each printing color. The Scitex command COMBSEP performs this conversion. This step is not necessary if 

G-3. Scitex Processing to Produce Color Separates 33 
the color separate information was added to the ARC/INFO 

coverages and passed to Scitex as the color channel values 

in TEXTEDIT files; the PLACR routine is also not necessary. For well-constructed and carefully edited ARC/INFO 

map coverages, the substantial decrease in Scitex computing requirements caused by adding color channel items in 

ARC/INFO may outweigh the advantages of the computerized error-checking inherent in PLACR. 

A color separate file can also contain linework 

information. Lines may be colored and symbolized on the 

basis of the Scitex channel number; this number can contain 

values for an .AAT item value passed from ARC/INFO to 

the Scitex DIGIT file. A Scitex Font Library should be 

created, containing only the line characters (for example, a 

solid line 0.015 in. wide) and colors to be plotted. The item 

values for lines not intended for plotting (that is, scratch 

boundaries between certain map units) will not be listed in 

the Font Library and will not be plotted. When the DIGIT 

file is rasterized, the Font Library is accessed to produce the 

symbolized lines. An ARCPLOT plotfile, transferred to 

Scitex with the PLOTSCITEX command, can also be used 

to generate the symbolized lines. When this plotfile is used, 

an appropriate Scitex line weight is assigned to the DIGIT 

file before it is rasterized. 

Prior to generation of color separates (negatives), the 

validity of the Scitex raster map is commonly checked on a 

color plot from an electrostatic plotter. For such plotters in 

use at the USGS, resolution is roughly equivalent to RES4 

on the Scitex. For plotting, the color-fill files should be 

rescaled to reduce the number of pixels to that appropriate 

to RES4. This rescaling will greatly increase plotting speed. 

The line files need not be rescaled. 

G-4. Converting ARC/INFO Coverages to DLG Format and 

Outputting to Tape 

For certain map production procedures, ARC/INFO 

coverages may need to be reformatted into digital line graph 

files (DLG's). The ARC/INFO command ARCDLG does 

this, producing DLG-3 optional format files. The command 

has several optional arguments. As will be noted by 

comparison of the following dialog with examples given in 

the ARC/INFO manual, certain arguments are not needed to 

convert certain coverages (for example, the "pointcover" 

argument is not needed if a polygon coverage is to be 

converted to a DLG). The unneeded arguments should be 

represented in the command string by a #. For polygon or 

line coverages, we used the command with selected arguments, as follows: 

Arc: ARCDLG <polygon or line coverage> 

<DLG filename> # # # <projection file> 

# # <header file> NOTRANS 

The ARCDLG command will not allow a point 

coverage to be converted to a DLG. A point coverage may, 

however, become part of a DLG if it is appended to a 

polygon or line coverage as follows: 

Arc: ARCDLG <polygon or line coverage> 

<DLG filename> <point coverage># # 

<projection file> # # <header file> 

NOTRANS 

The header for a DLG contains information on the 

comer tics and projection parameters. This information is 

passed to the DLG by the projection and header files, which 

are created by the user. Their file contents and formats are 

shown below. For full information, consult the ARC/INFO 

manual. 

For a map area in the Northeastern United States, the 

projection file may appear as follows: 

INPUT 

PROJECTION LAMBERT 

UNITS METERS 

ZONE 61 

PARAMETERS 

40 40 00 

43 20 00 

-81 00 00 

42 00 00 

0.0 

0.0 

END 

For the same map area, the header file may appear as 

follows: 

MAPNAME THICKNESS 

CATEGORY HYPSOGRAPHY 

SOURCEDATE 1989 

RESOLUTION 25.40 

SCALE 1 000000 

CONTROLPOINT SW 40.00 -84.00 

-256222.000 -217600.800 

CONTROLPOINT NW 44.00 -84.00 

-240658.800 226384.500 

CONTROLPOINT NE 44.00 -78.00 

240657.800 226384.600 

CONTROLPOINT SE 40.00 -78.00 

256221.600 -217697.400 

The DLG must commonly be written to magnetic tape 

in ASCII format. From PRIMOS, files are commonly 

written to tape by the WRITE option of the MAGNET 

subroutine. However, unless otherwise specified, this command produces a tape file that does not strictly conform to 

industry standards for ASCII. It can be read back into 

PRIMOS with no problem, but it cannot be successfully 

read by other computer systems. The following CPL, 

written by Carl L. Rich (USGS), specifies the proper, 

industry-standard ASCII format: 

34 A User's Manual for a Method of Map Scanning and Digital Editing 
&ARGS FILENAME; FILENUM 

&IF [NULL %FILENAME%] &THEN &DO 

TYPE 

TYPE USAGE: <cpl name> <dlg.filename> 

<magnetic tape file number> 

TYPE 

&RETURN 

&END 

&IF [NULL %FILENUM%] &THEN &S FILENUM := 1 

&IF [EXISTS %FILENAME% -FILE] & THEN &DO 

TYPE 

TYPE File %FILENAME% does not exist 

TYPE 

&RETURN 

&END 

&DATA MAGNET 

DECLARE TAPE TAPE=(O),LRECL= 

(80),BFACTOR=(1 OO),BUFFERS=(1) 

MODIFY TAPE DENSITY=(6250),FILENO= 

(%FILENUM%) 

DECLARE DISK DISK=(%FILENAME%),LRECL= 

(80) 

TRANSLATE TAPE (A*) 

WRITE DISK TAPE 

QUIT 

&END 

&RETURN 

The CPL is invoked as follows: 

OK, CPL <cpl name> <dlg.filename> <magnetic 

tape file number> 

REFERENCES CITED 

Aronoff, Stanley, 1989, Geographic information systems; A 

management perspective: Ottawa, Canada, WDL Publications, 294 p. 

Soller, D.R., in press a, Map showing the thickness and character 

of Quaternary sediments in the glaciated United States east of 

the Rocky Mountains-Northeastern States, the Great Lakes,. 

and parts of southern Ontario and the Atlantic offshore area 

(east of 80° 31' west longitude): U.S. Geological Survey 

Miscellaneous Investigations Series Map I-1970-A, scale 

1:1,000,000. 

--in press b, Map showing the thickness and character of 

Quaternary sediments in the glaciated United States east of 

the Rocky Mountains-Northern Great Lakes States and 

Central Mississippi Valley States, the Great Lakes, and 

southern Ontario (80° 31' to 93° west longitude): U.S. 

Geological Survey Miscellaneous Investigations Series Map 

I-1970-B, scale 1:1,000,000. 

--in press c, Map showing the thickness and character of 

Quaternary sediments in the glaciated United States east of 

the Rocky Mountains-Northern and Central Plains States 

(90° to 103° west longitude): U.S. Geological Survey Miscellaneous Investigations Series Map I-1970-C, scale 

1:1,000,000. 

---in press d, Map showing the thickness and character of 

Quaternary sediments in the glaciated United States east of 

the Rocky Mountains-Northern Plains States (west of 103° 

west longitude): U.S. Geological Survey Miscellaneous 

Investigations Series Map I-1970-D, scale 1:1,000,000. 

Utz, L.G., Cialek, C.J., Lawson, H.S., and Doughty, E.F., 1988, 

Technique development for digital production of a Quaternary sediment map: American Congress on Surveying and 

Mapping (ACSM)-American Society for Photogrammetry 

and Remote Sensing Fall Convention, Virginia Beach, Va., 

Sept. 11-16, 1988, ACSM Technical Papers, p. 162-167. 

References Cited 35 
APPENDIX, DESCRIPTION OF THE PROTOTYPE METHOD 

Linework for the test map consists of inked compilations on four scale-stable film positive separates. To convert 

these separates to a digitally produced map, a prototype 

method was devised to use hardware and software available 

at the U.S. Geological Survey (C.J. Cialek, USGS, written 

commun., 1987; Utz and others, 1988). This prototype 

method, with steps 15-22 modified slightly by Soller during 

data processing, is briefly summarized below and in figure 

A-1. Only steps 14-23 can be performed by the map author 

or project scientist. 

(1) Author-drafted linework for each of the four separates 

is prepared for digital scanning by removal of map 

symbols and their leaders and touchup of linework. 

A wipe-on color proof is used as the scan copy. This 

copy contains linework in black, the cultural base in 

yellow, and the quadrangle border and neatline in 

red. The quadrangle comers are used later to project 

the coverages for Scitex and Intergraph editing. 

(2) A raster scan of each separate is performed on a Scitex 

Super Color Scanner at RES 17 or RES34 (17 or 34 

Scitex pixels per millimeter). 

(3) Raster files are thinned to 1-pixel width, edited, and 

vectorized on the Scitex editing workstation. 

(4) Files are written to magnetic tape. 

(5) Each file is loaded onto the DLG (digital line graph) 

processor, a computer where the files are converted 

to DLG format by use of the National Mapping 

Division's (NMD's) PROSYS1 software. The Scitex vector file contains only scanned lines; 

PROSYS checks for errors in lines (for example, 

intersections), establishes topology, and adds area 

labels. 

(6) Each DLG is written to magnetic tape. 

(7) The tape is loaded onto an Intergraph computer and 

converted via NMD' s RETSAM2 software to Intergraph format. 

(8) On the Intergraph editing workstation, and with the 

aid of commands assigned to tablet menus, proper 

attribute values are assigned to each polygon interactively, and additionallinework editing is done as 

needed. 

(9) The validity of each file is checked on electrostatic 

plots. 

(10) Each file is converted to Altek data format by RETSAM software. 

(11) Files are written to magnetic tape. 

1

Information on PROSYS is available from the USGS, 526 National 

Center, Reston, VA 22092. 2

Information on RETSAM is available from the USGS, 562 National 

Center, Reston, VA 22092. 

(12) Files are read into the DLG processor for restructuring 

by PROSYS software and for creation of DLGformatted output. If PROSYS detects errors in a 

file, steps 5-12 must be repeated until all errors 

detected by PROSYS are eliminated. 

(13) Standard-format DLG's are written to magnetic tape. 

( 14) Tape is copied to the disk of a computer that has 

ARC/INFO GIS software. 

(15) DLG's are converted to ARC/INFO format; each DLG 

file becomes an ARC/INFO coverage. DLG's containing both point and line information (for example, the miscellaneous point and line map separate) 

will be separated into two coverages. The 

ARC/INFO command DLGARC is designed to 

convert a DLG into one or more ARC/INFO coverages. However, our maps had to be converted by 

a program ("CDLG .AML") written by one of the 

authors (Lanfear) because the DLGARC converter 

in ARC/INFO could not read the DLG's we were 

provided. 

( 16) Prior to ARC/INFO editing, all coverages for a given 

quadrangle (surficial, thickness, subsurface, and 

miscellaneous point and line data) must be precisely 

registered to each other; for some quadrangles, the 

TRANSFORM command in ARC or the ADJUST 

command in ARCEDIT was required to distort or 

"rubber-sheet" coverages into proper registration. 

(17) In ARCEDIT, lines and polygon labels are checked 

and edited as needed. Editing efficiency is 

improved through the use of a customized AML 

(Arc macro language) program with pulldown 

menus, which was written by one of the authors 

(Lanfear). 

(18) The validity of map data is checked in ARCPLOT on 

a graphics display terminal. After any errors have 

been corrected in ARCED IT, electrostatic plots are 

generated for a final check. 

( 19) Two coverages, character of surficial deposits and 

thickness of Quaternary sediment, are combined so 

that resultant polygons contain information from 

both coverages, and can, therefore, be assigned 

unique map colors. Coverage items are renamed as 

appropriate; then the coverages are merged by the 

UNION or INTERSECT command, and sliver polygons (artifacts of combining coverages in which 

lines are nearly parallel) are removed by the ELIMINATE command. This procedure is explained in 

section F-7. 

(20) The validity of map data is checked in ARCPLOT on 

a graphics display terminal. After any errors have 

been corrected in ARCED IT, electrostatic plots are 

generated for a final check. 

36 A User's Manual for a Method of Map Scanning and Digital Editing 
MANUSCRIPT ____ _... 

MAP 

GIS DATA 

BASE 

prepare map 

to be scanned 

format 

PAPER 

MAP 

Figure A-1. Steps in digital production of maps by the prototype method. Diagram modified from C.j. Cialek (U.S. 

Geological Survey, written commun., 1987). DLG, digital line graph; mag., magnetic; GIS, geographic information 

system. 

Appendix, Description of the Prototype Method 37 
(21) At this point, coverages can be developed into a GIS 

data base (not discussed in this report). 

(22) For the coverage that contains the combined surficial 

and thickness information, the polygon attributes 

are renamed. New items are added to the polygon 

attribute table (.PAT) in the format required by the 

DLG processor software. An AML written by one 

of the authors (Soller) is used to assign unique 

values to the new items on the basis of the values for 

the surficial deposits and thickness items. For each 

coverage, values for a line-type item in the arc 

attribute table (.AAT) are changed to provide the 

appropriate code for line type (for example, solid, 

scratch, dashed). Each coverage is then converted 

to optional DLG format via the ARCDLG command 

with the NOTRANS option (see section G-4 for 

details). 

(23) The DLG's are written to magnetic tape. 

(24) The DLG's are read onto an Intergraph computer and 

modified to Altek format to become readable by the 

DLG processor. 

(25) Files are written to magnetic tape. 

(26) Files are loaded onto the DLG processor for PROSYS 

structuring. Polygon attribute codes (the new .PAT 

item values in step 22) are converted to a format 

translatable by NMD' s GEOSPOT3 software into 

Scitex color channels. 

(27) For each file, polygon information from GEOSPOT 

processing and line information from PROSYS 

processing are converted to Scitex format. 

(28) Scitex-formatted files are written to tape. 

(29) Files are read onto the Scitex system for generation of 

negatives. This procedure can be lengthy and complex and is briefly discussed in this report. 

3

Information on GEOSPOT is available from the USGS, Mail Stop 

531, 345 Middlefield Road, Menlo Park, CA 94025. 

38 A User's Manual for a Method of Map Scanning and Digital Editing 


SELECTED SERIES OF U.S. GEOLOGICAL SURVEY PUBLICATIONS 

Periodicals 

Earthquakes & Volcanoes (issued bimonthly). 

Preliminary Determination of Epicenters (issued monthly). 

Technical Books and Reports 

Professional Papers are mainly comprehensive scientific reports 

of wide and lasting interest and importance to professional scientists 

and engineers. Included are reports on the results of resource studies 

and of topographic, hydrologic, and geologic investigations. They also 

include collections of related papers addressing different aspects of a 

single scientific topic. 

Bulletins contain significant data and interpretations that are of 

lasting scientific interest but are generally more limited in scope or 

geographic coverage than Professional Papers. They include the results 

of resource studies and of geologic and topographic investigations, as 

well as collections of short papers related to a specific topic. 

Water-Supply Papers are comprehensive reports that present 

significant interpretive results of hydrologic investigations of wide 

interest to professional geologists, hydrologists, and engineers. The 

series covers investigations in all phases of hydrology, including 

hydrogeology, availability of water, quality of water, and use of water. 

Circulars present administrative information or important scientific information of wide popular interest in a format designed for 

distribution at no cost to the public. Information is usually of short-term 

interest. 

Water-Resources Investigations Reports are papers of an 

interpretive nature made available to the public outside the formal 

USGS publications series. Copies are reproduced on request unlike 

formal USGS publications, and they are also available for public 

inspection at depositories indicated in USGS catalogs. 

Open-File Reports include unpublished manuscript reports, 

maps, and other material that are made available for public consultation 

at depositories. They are a nonpermanent form of publication that may 

be cited in other publications as sources of information. 

Maps 

Geologic Quadrangle Maps are multicolor geologic maps on 

topographic bases in 7.5- or 15-minute quadrangle formats (scales 

mainly 1:24,000 or 1 :62,500) showing bedrock, surficial, or engineering geology. Maps generally include brief texts; some maps include 

structure and columnar sections only. 

Geophysical Investigations Maps are on topographic or planimetric bases at various scales; they show results of surveys using 

geophysical techniques, such as gravity, magnetic, seismic, or radioactivity, which reflect subsurface structures that are of economic or 

geologic significance. Many maps include correlations with the geology. 

Miscellaneous Investigations Series Maps are on planimetric or 

topographic bases of regular and irregular areas at various scales; they 

present a wide variety of format and subject matter. The series also 

includes 7 .5-minute quadrangle photogeologic maps on planimetric 

bases that show geology as interpreted from aerial photographs. Series 

also includes maps of Mars and the Moon. 

Coal Investigations Maps are geologic maps on topographic or 

planimetric bases at various scales showing bedrock or surficial 

geology, stratigraphy, and structural relations in certain coal-resource 

areas. 

Oil and Gas Investigations Charts show stratigraphic information for certain oil and gas· fields and other areas having petroleum 

potential. 

Miscellaneous Field Studies Maps are multicolor or blackand-white maps on topographic or planimetric bases on quadrangle or 

irregular areas at various scales. Pre-1971 maps show bedrock geology 

in relation to specific mining or mineral-deposit problems; post-1971 

maps are primarily black-and-white maps on various subjects such as 

environmental studies or wilderness mineral investigations. 

Hydrologic Investigations Atlases are multicolored or blackand-white maps on topographic or planimetric bases presenting a wide 

range of geohydrologic data of both regular and irregular areas; 

principal scale is 1:24,000, and regional studies are at 1:250,000 scale 

or smaller. 

Catalogs 

Permanent catalogs, as well as some others, giving comprehensive listings of U.S. Geological Survey publications are available under 

the conditions indicated below from the U.S. Geological Survey, 

Books and Open-File Reports Section, Federal Center, Box 25425, 

Denver, CO 80225. (See latest Price and Availability List.) 

"Publications of the Geological Survey, 1879-1961" may be 

purchased by mail and over the counter in paperback book form and as 

a set of microfiche. 

"Publications of the Geological Survey, 1962-1970" may be 

purchased by mail and over the counter in paperback bobk form and as 

a set of microfiche. 

"Publications of the U.S. Geological Survey, 1971-1981" may 

be purchased by mail and over the counter in paperback book form (two 

volumes, publications listing and index) and as a set of microfiche. 

Supplements for 1982, 1983, 1984, 1985, 1986, and for subsequent years since the last permanent catalog may be purchased by 

mail and over the counter in paperback book form. 

State catalogs, "List of U.S. Geological Survey Geologic and 

Water-Supply Reports and Maps For (State)," may be purchased by 

mail and over the counter in paperback booklet form only. 

"Price and Availability List of U.S. Geological Survey Publications," issued. annually, is available free of charge in paperback 

booklet form only. 

Selected copies of a monthly catalog "New Publications of the 

U.S. Geological Survey" are available free of charge by mail or may 

be obtained over the counter in paperback booklet form only. Those . 

wishing a free subscription to the monthly catalog "New Publications of 

the U.S. Geological Survey" should write to the U.S. Geological 

· Survey, 582 National Center, Reston, VA 22092. 

Note.-Prices of Government publications listed in older catalogs, announcements, and publications may be incorrect. Therefore, 

the prices charged may differ from the prices in catalogs, announcements, and publications.