Technical Paper 356 3 A D

AN APPROACH TO ASSESSMENT OF RELIEF

I FORMATS FOR HARDCOPY TOPOGRAPHIC MAPS

Lawrence M. Potash, John P. Farrell, Thomas E. Jeffrey

HUMAN FACTORS TECHNICAL AREA

D DDC

U. S. Army

April 1979\/

A ptOved lot public tolesil. d.ltibution unlimlted,

06 04 '9 020
U. S. ARMY RESEARCH INSTITUTE

FOR THE BEHAVIORAL AND SOCIAL SCIENCES

A Field Operating Agency uinder the Jurisdiction of the

Deputy Chief of Staff for Personnel

WILLIAM L. HAUSER

JOSEPH ZEIDNER Colonel, US Army

Technical D)irector Commander

NOTICES

t)ISTRIBUTION Nst ditribution of this rep~ort hall b441 mnade byv AJRI P111AW adclross cortotparndonzo

containing distribution of topotl to U S Arrmy Reuoch Injt~tu@ #()t the Beaviral &Ad Social Sciencet.

ATTN PEPI-P, 5001 E,venh,.ar Avviuv, Aie~xzitta, Vitynia 22l333

FINAL DS5POSITION Thit reort may he destroyed .r1t0n 11 it no longer twvded Plows do not titurn 0t to

the U. S, ArmV Resuach Institute ftot the Behaorul arnd S4C&Ia SCIenW.

NOQTE The findings in thist report are not to be construed as on ofi'ciai Departrnent of the AMV 010oJ,

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Army Research Institute for the Behavioral & AREA 4 WORK UNIT NUMBERS

Social Sciences (PERI-OS)

1I. CONTROLLINC.OFFICE NAME AND ADDRESS 12. REPORT MF

j US Army Engineer Topographic LaboratrJ ' April 1979,

Fort Belvoir, VA 22060 9 101"r'AE

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16. $tJPPI. EMENTARY NOTES

It, KEY WORDS (Cantft nu enoMate a* of n#C*#*,VVO I,4AtE..f(V by black nwmbet) Map design Layer tints Mal) legibility Map assessment Vistial display research Terrain visualization

Helief portrayal Topographic maps 3pot olevation

Halp symbols Hardecopy maps Landforn identification

Contour lines Cartography Defilal1e

A AilS VACT (Ctk" am Mv**a 44 If ttoa mW I4d.sirt 61t INIA111~, the relief assessment test described in this report it. deyiqtned to assess the

effect Of SLupplemontinq contour lines with other relivf formats . It contains

eight types of probloms and a review of relevant aspect~s of map) reading. It

has boen produced tn three relief formats. contour lines, contour lines Plus layer tints. and contour lines' plus shading. Initial wtrk indicates that addition of layer tints; to contour lines can increase speed of reading some types or relief information: whereas, addition of shddrlifde6otices map

rieadinq -',peerl more than use of layer tint-, and can cau~e a dcr ease in accura.?

DO U7 13 E ofi. I *SOV 66 1b a~ew~a

SEcu06TYV "MnAVIctON' OI'.TI PAGE fWXMq "1"40)fud

1-10~ e-z~
I1rTcTAqqTFFD

SECURITY CLASSIFICATION OF Th.S PAGE(171.a Date Ented)

~2O 1a~designers will be ~interested in this report.

NTIS G~A& .1 D2DC TAR

4 I

UNCLASS I iFI tD

SEUIYc4.O HS ~t~"Oarrfi
Technical Paper 356

AN APPROACH TO ASSESSMENT OF RELIEF

FORMATS FOR HARDCOPY TOPOGRAPHIC MAPS

Lawrence M. Potash, John P. Farrell, Thomas E. Jeffrey

Submitted by:

Edgar M. Johnson) Chief

HUMAN FACTORS TECHNICAL AREA

Approved BY:

A. H. Birnbaurn, Acting Director

ORGANIZATIONS AND SYSTEMS

RESEARCH LABORATORY

Joseph Zeidner

TECHNICAL DIRECTOR

U.S. ARMY RESEARCH INSTITUTE FOR THE BEHAVIOR~AL AND SOCIAL SCIENCES

5001 Eisenhower Avenue. Alexandria, Virginia 22333

Office. Deputy Chief of Staff for Personnel

Oepatmnt of the Army

April 1979

Army roject Number Topographic Products and

201627117A7211 PocedureS

A4p&Aad for pulic #61w;~ diLuoi' uoIrtitd
ARI Research Reports and Technical Papers are intended for sponsors of

R&D tasks and other research and military agencies. Any findings ready for

implementation at the time of publication are presented in the latter part of

the Brief. Upon completion of a major phase of the task, formal recommendations for official action normally are conveyed to appropriate military

agencies by briefing or Disposition Form.

I
FOREWORD

The Human Factors Technical Area of the Army Research Institute (ARI)

is concerned with the demands of the future battlefield for increased

man-machine complexity to acquire, transmit, process, disseminate, and

utilize information. The research is focused on the interface problems

and interactions within command and control centers and is concerned with

such areas as topographic products and procedures, tactical symbology,

information management, user-oriented systems, staff operations and

procedures, and sensor systems integration and utilization.

One area of special interest is that of human factors problems in

the design of topographic products and procedures. Maps are an essential part of a large number of military tasks at all staff levels. Many

map users report, and have, difficulty in visualizing terrain features

from current maps which use contour lines to portray relief. Methods

for supplementing contour lines with other relief formats have been developed but assessing the value of supplementing contour lines with other

modes of relief portrayal remains a problem. In order to make a decision

regarding the cost-benefits tradeoff of supplementing contour lines, the

map designer must have some idea of how different supplementary relief

formats will affect user performance. This publication presents a technique for assessing map relief legibility and reports initial findings

from employing this technique to evaluate use of shading and layer tints

as supplementary relief formats. The results of this initial work indicate that adding layer tints to contour lines is beneficial for some

types of map reading tests. However, addition of shaded relief to contour line maps offers no advantages over the addition of layer tints,

and can decrease performance for some tasks.

This research effort is responsive to requirements of Army Project

2QI62717A721 and to special requirements of the USA Engineering Topographic Laboratory. Special requirements are contained in Hluman Research

Need 76-183, "Topographic Product Design and Test Methodology."

This research effort was made possible through the assistance of

Alex Pearson and John Griffin of the USA Engineering Topographic Laboratory and through the cooperation of the 2nd Armoured Division, Fort

Hood, Tex.

Y 0b EPU El ER

' e'hnica li rector

A
AN APPROACH TO ASSESSMENT OF RELIEF FORMATS FOR TOPOGRAPHIC MAPS

BRIEF

Requirement:

To develop an appropriate methodology and carry out an assessment

of the legibility of different relief formats.

Procedure and Findings:

The types of relief information that must be extracted by representative users of hardcopy maps were analyzed. Using the results of this

analysis, a Relief Assessment Test was designed to determine the merits

of supplementing contour lines with other relief formats. The Relief

Assessment Test contains eight types of problems: landform identification, ridge-valley identification, slope identification, identification

of high-low areas on the map, spot elevation problems, vertical profile

identification, terrain visualization, and defilade. Use of the Relief

Assessment Test assumes previous experience and training in the use of

contour line maps, but the test does contain a review of zelevant aspects of map reading. When this test is administered as a self-paced

test, subjects typically take 3 to 5 hours.

The Relief Assessment Test was produced in three foxmatsi contour

lines, contour lines plus layer tints, and contour lines plus shading.

Initial research was undertaken to assess these three map formats empirically. Subjects were 48 Army officers and NCOs experienced in reading contour maps and using them for land navigation. Subjects were

tested in small groups, each subject being told to work at his own rate

of speed. Each subject was assigned to one of the three map formats.

"M:e results of this initial research indicate that addition of layer

tints to contour lines can increase speed of extracting some types of

relief information. On the other hand, addition of shaded relief does

not increase map reading speed more than use of layer tints, and can

cause a decrease in accuracy.

.1
Utilization of Findings:

The Relief Assessment Test can be produced in a number of relief

formats to compare their relative merits. It could be used as an assessment test of relief-related map reading skills or, with feedback to the

user, as part of a course to teach reading of relief information presented on hardcopy topographic maps. The assessment of the relative

merits of the three map formats undertaken in this study provides the

map designer with valuable information concerning how adding different

supplementary relief formats to contour lines will affect user performance. This information is essential it the map designer is to make an

informed decision regarding the cost-benefits tradeoff of supplementing

contour lines to increase map relief legibility.

fAI' 

4.
AN APPROACH TO ASSESSMENT OF RELIEF FORMATS FOR TOPOGRAPHIC MAPS

CONTENTS

Page

INTRODUCTION ........ . • • . . . . . . . . . . .. . 1 1

DESCRIPTION OF THE TEST .. •......... ....... 2

Landform Identification . . ................... 2

Ri4ge-Valley Identification . . . . . . . ........... 2

Slope Identification ..................... . 2

Identification of High-Low Areas on the Map ........... 6

Spot Elevation Problems ................ ..... 6

Vertical Profile Identification . . . . . . . . ......... 7

Terrain Visualization . . .................. 9 9

DESCRIPTION OF TEST CONSTRUCTION ............. . .... 12

DESCRIPTION OF MANNER IN WHICH TEST IS

DESIGNED FOR USE • • . . . . . . . . . . . . . . . . . . 13

TRAINING NECESSARY FOR TEST USE . .• . . . . . . . .• . • . . . 13

INITIAL RESEARCH . . , . . • . . . ...... . . . . . *. • . . . 14

Subjects & . a 0 a . . 0 . a 0 0 4 0 0 0 . * 0 a . . * a 0 0 0 14

Procedure a * * * e s * # * * * , * * s * 9 9 .* * * * 14

Results 0 . • * . 9 9 9 • 9 9 9 9 9 9 o 9 o . . . * 14

Discussion and Conclusionse 99999, . .17

RE'ERENCES . . e . . o . . . . . * . . . * . . . . . . . . . . 20

LIST OF TABLES

Table 1. Number of map seV ents, questions per map

segment, and total number of questions

used for each problemtype t.yp. ....... ...... 9

2. Mean of median times required to answer

questions (min) . . ......... 9.. . . * 15

3. Mean number of correct answers ........... . .16
Page

LIST OF FIGURES

Figure 1. Photograph of a simple overprinted map segment

and sample landform sketches used in landform

identification problems ................

2. Photograph of a sample overprinted map segment

used in ridge-valley identification problems . . .... 4

3. Photograph of a sample overprinted map segment

and line drawings illustrating slopes used in

slope identification problems .............

4. Photograph of a sample overprinted map segment

used in identification of high-low areas on the

map problems . . . ............ . .... 6 6

5. Photograph of a sample overprinted map segment

with accompanying contour interval information

used in spot elevation problems ............ 7

6. Photograph of a sample overprinted map segment,

line drawings illustrating vertical profiles,

and accompanying scale and contour interval

information used in vertical profile identification problems ...

7. Photograph of a sample overprinted map segment,

drawing of scene viewed by the observer, and

accomp.-aing contour interval, scale, angle of

vision and maximum range information used in

terrain visualization problems , . . , . . . . . . . . . 10

A 8 Photograph of a sample overprinted map segment

and accompanyinq scale and contour interval

information used in defiladu problems . . . . . . .. , 11
AN APPROACH TO ASSESSMENT OF RELIEF FORMATS FOR

HARDCOPY TOPOGRAPHIC MAPS

INTRODUCTION

Two techniques have been used extensively for assessing the effectiveness of maps as visual displays: (1) opinion surveys of user preferences; and (2) performance testing in field exercises. The survey of

user preference is inexpensive and it provides information on the degree

of user acceptance but user preference surveys have questionable predictive validity for performance with maps (Wheaton, Zavala and Van Cott,

1967). In one study, preference judgments were found to be useless as

predictors of performance under daylight conditions and only on the night

task were there any significant correlations between preference and performance (Hill, 1974). Field tests of performance with maps present

other difficulties: (1) many of the operational tasks used in the field

testing are complex and require a number of skills other than those involved in reading maps; (2) field testing of maps is expensive; and

(3) a very large number of variables, such as terrain, seasonal changes

in vegetation, etc., are present and must be controlled.

Due to these difficulties with existing techniques for the assessment of maps, the test described in this paper was developed utilizing

a class-room approach to the evaluation of map products. The test is

used to obtain measures of how well alternative map products provide

information to the user. A similar approach for assessing the relative

legibility of different relief formats has been developed with imaginary terrain based on sections of the Atlantic sea floor (Phillips,

DeLunia and Skelton, 1975). Currently most maps, including U.S. Army

maps, portray terrain by the use of contour lines because they provide

more precise quantitative information than other techniques. However,

a large percentage of map users report difficulty visualizing terrain

7 when contour lines are the only guide (Skop, 1958). Supplementary modes

of relief portrayal have been added to contour lines to alleviate this

problem. The test described in this paper is designed to assess quantitatively the value of adding supplementary relief to contour lines. Although the approach used by Phillips, et al. (1975) was innovative, there

was not adequate control for information content of the map stimuli. In

our test, infotation content was controlled by comparing different map

formats on the same terrain and tho problem of terrain-simcific results

was avoided by using 52 map segments representing a wide range of different torrain-contour interval combinations. Mnother important feature in

our test is that hydrography and cultural features were present in the

map seTments. Since water flows downhill, hydrographic features may

convey a considerable amount of terrain relief i£nformation. Due to the

,1.

V
artificial nature of the terrain in the test of Phillips, et al., hydrography and cultural features are not present. This paper describes our

test for relief assessment and presents initial results obtained using

the test.

DESCRIPTION OF THE TEST

dtracted In order to determine what types of relief information must be ex- from maps by representative users, we studied and analyzed Army

Field Manual FM 21-16, "Map Reading," literature on relief portrayal and

land navigation and discussed relief portrayal with personnel at the Infantry School at Fort Benning and the Topographic Products Design Branch,

USAETL. Although this test is responsive to the needs of military de-

- signers, it should be useful in other contexts in which assessment of

different relief formats or user ability to extract information from

those formats is desired. The following problem types are used in the

Relief Format Assessment Test (map segments described below are 4000 m

grid squares except for the high-low area problem which uses 8000 m grid

squares):

Landform Identification

The subject is asked to identify landforms beneath the tips of arrows

overprinted on map segments. The landforms to be identified (hill, valley, spur, depression, and saddle) are illustrated by pencil sketches

(representative map segments and landform illustrations are shown in

Figure 1). Note that the map segment shown in Figure I is a somewhat

reduced black and white photograph of the original colored contour line

map segment and is repr-sentative of other 4000 m map segments described

below.

K'l Ridge-Valley Identification

The subject is asked to decide whether each of the lines overprinted

on map segments runs along: (a) a valley; (b) a ridge-spur; or, (c) terrain that does not fall exclusively into categories a or b (representative

map segment is shown in Figure 2).

Slope Identification

The subject is asked to decide whether each of the lines overprinted

on map segments runs alongt (a) a uniform up slope; (b) a uniform down

slope; (c) a convex up slope; (d) a convex down slope; (e) a concave up

slopel and, (f) a concave down slope. Each of the slopes is illustrated

by a simple line drawing (representative map segment and slope illustrations are shown in Figure 3).

2
Ait

I.U

. P.4
57-

'44
It 'LI a

1. up cncav . Coca~edo4

I.7

3convex up 4. Cobves down

So wasfore up *n unfre down

Figure 3. Photograph of a samzple overprinted m~ap segment and line

drawings illustrating slopes used in slope identification problem.,
Identification of High-Low Areas on the Map

The subject is asked to identify the four 1000 metre x 1000 metre

grid squares (referred to as 1000 metre grid squares) containing the

highest elevations and the four 1000 metre grid squares containing the

lowest elevations on a map segment containing sixty-four 1000 metre grid

squares. Numbers are overprinted on each of the grid squares for ease

of identification. Contour interval is provided (representative map

segments are shown in Figure 4).

. . . , ., :4 .'t, \ " '

6 'l . ' d...

... p..-

A.".

6-1

y').

33 W _

41 A- 4856

t63~

C3ontou tInterval 40 It.

Figure 4. Photograph of a sample overprinted map segment used in

identification of high-low areas on the map problems.

Spot Elevation Problems

The subject is asked to identify the elevation at different points

overprinted on map segments* Contour interval is provided (representative

.map segment is shown in Figure 5).

6

Va
.,4-. w.***PI~ -..-

4, 1?fu 1

-W/

contour interval 20 ft.

Figure 5. Photograph of a sample overprinted map segmlent with

accompanying contour interval information used in spot

elevation problems.

Vertical Profile Identification

The subject is asked to decide which of three alternative profiles

beat matches the vertical profile of terrain beneath each of two lines

overprinted on the map segments* %be subject must utilize available

scale and contour interval Information. Contour interval and scale are .1 prov~ided (representative map segment and accompanying profiles are shown

in Figure 6).

7
N4 J

I ijt

20p

j 1.3

identifitio tiSoC ms
Terrain Visualization

Four arrows are overprinted on each of the map segments. The subject attempts to visualize the scene he would see if he were standing at

the arrowtip looking in the direction shown by the arrow. The subject

must decide which scene best matches the drawings shown on the opposite

page. Contour interval, scale, angle of vision, and maximum range are

provided (representative map segment and accompanying scene are shown

in Figure 7).

Defilade

The subject is asked to determine intervisibility between various

points overprinted on map segments. Contour interval and scale are

provided (representative map segment and accompanying scene shown in

Figure 8).

The test provides separate scores for each problem type so that the

relative merits of the relief forms can be assessed as a function of the

type of information extracted from the map.

A breakdown showing the number of questions devoted to each problem

type is shown in Table 1.

Table 1

Number of Map Segments, Questions per Map Segment, and Total

Number of Questions Used for Each Problem Type

Problem types (listed Number of

in order in which they Number of questions per Total number

are presented in test) map segments map segment questions

Landform identification 4 4 16

Ridge-valley

identification 4 8 32

Slope identification 4 4 16

Identification of

I : Spot high-low elevation areas on mip 8 8 64

problems 4 8 32

Vertical profile

identification 8 2 16

Terrain visualization 16 1 16

Defilade 4 6 24

9

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liettba o -an ti eakOwal Wfo

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Fiur hoogap 8 f smleovrpite mp emet n

adinstre inti1ahotets yiclytksfo o5hus

Pefrac is mesue intrso o cuaeyadqickyrle

inomto setatd rmagvnrle ora.7i ethsbe

prdvdi he rle omtacotu iecntuIie upe metdwt ae itadcnorlnssplmne ihsaig

Laye tins ar coosu o eparae e teiit isic
elevation bands. The contour line plus layer tint maps use 3-4 colors

(white, yellow, tan, brown) to indicate different ranges of elevation;

the exact number of colors used depends on the range of elevation portrayed in the map segment. The 4000 m contour line plus layer tint map

segment contains 2-3 layer tints whereas the 8000 m map segments used

in the high-low problem contain 3-4 layer tints.

For the maps portraying relief with contour line plus shading, the

light is assumed to originate in the Northwest so that northwestern

and western slopes are unshaded while the eastern and southeastern slopes

are in the shade. The degree of slope is indicated by the degree of

shading with the eastern slope being darker. Shading was done in grey

using the airbrush technique.

DESCRIPTION OF TEST CONSTRUCTION

Four terrain-contour interval combinations were used in order to

insure that map test would not be biased toward a given terrain-contour

interval combination. The contour intervals represented on the maps

range from 3 to 24 m. The elevation ranges (high elevation minus low

elevation) represented on the maps ran from 85 to 1830 m. When scale

is constant, map designers increase contour interval with increasing

elevation range so that the contour lines can adequately portray the

terrain without merging. The contour intervals were typical for the elevation ranges portrayed on the four maps. With the exception of vegetation features which were removed, the map stimuli used in the contour

line version of the test are portions of "off the shelf" 1:50 000 scale

maps since any deviations from a "map-like" appearance may affect the

subjects' ability to perceive relief.

In order to minimize the influence of possible experimenter bias

upon development of the test questions, randomization was used whenever

possible. The maps were divided into 4000 m grid squares (at 1:50 000

scale, 4000 m is 8 cm). For each question, a random number table was

used to select a 4000 m grid square to serve as the map stimulus. For

the high-low areas on the map problem, 8000 m grid squares were randomly

selected from the remaining portions of the map sheets. In the high-low

areas on the map problem, the influence of possible experimenter bias

in development of map stimuli was minimal. Once the map areas had been

chosen, no further selection of landforms, slopes, etc., within the map

area was required to construct the question. For the vertical profile

identification problem and spot elevation problems, the areas within the

4000 m segment that would be used for the actual question were selected

by choosing appropriate 1000 m grid squares using a random number table

although positioning of the overprinted stimuli within areas was done

using expert judgment. For the other question types, both the area within the 4000 m grid square used in the question and the position of overprinted stimuli were selected by the experimenter.

12 1 -t2&
In the landform and slope recognition questions, the particular landforms (or slopes) that were to be illustrated on a given 4000 m grid

square were randomly assigned. Some adjustment was made so that each

type of landform was not represented too many times on a given map segment. We feel that the extensive sample of map segments and random assignment of these segments to the given problems in order to avoid

experimenter-bias further separates our assessment technique from other

experimental techniques reported in the literature. The scoring and

adjustments are described in more detail in the results and conclusion

section.

The test was developed in contour line format. After development

was completed, parallel versions of the test were produced in the other

relief formats by adding the appropriate supplementary relief to the

contour line maps.

Registration of the arrows, lines, etc., on the map background

proved to be a minor problem requiring adjustments in scoring in some

instances.

DESCRIPTION OF MANNER IN WHICH TEST IS DESIGNED FOR USE

Each problem type is scored separately. An overall or total score

across problem types would be meaningless since the importance of a particular advantage or disadvantage of a relief format depends on the function of the map. Implicit in a total score is an arbitrary weighting

for the different problem types. The test is administered so that each

subject works with only one format for the following reasons: (a) exposing the subject to different relief formats might prove confusing to

those who would have to go from one map format to another throughout the

test; (b) it would require more extensive review materiall (a) study of

one map format might facilitate (or hinder) use of another map format.

TRAINING NECESSARY [OR TEST USE

This test assumes previous experience and training in the use of

standard line maps. A map reading review for extracting terrain information required by a problem set is given to the subject prior to presenting the particular type of problem. For relief formats concerning contour

plus supplementary portrayal of relief, additional information is included

in the review relevant to the supplementary relief format. Problem types

are presented in an order that allows successive presentation of review

material with problems requiring the entire review material being placed

in the later portion of the test. Order of problem presentation is also

struotu ed to give subjects practice oa skills that may be needed to

L13

.
work more difficult problems. Fo: example, simple landform identification and ridge-valley identification problems provide practice in the

kinds of recognition that will be required in the visualization of terrain problems. Order of problem presentation was the same for all rel ief

formats.

INITIAL RESEARCH

This experiment was undertaken to assess the effects of the three

relief formats (contour line, contour lines plus layer tints, and contour

lines plus shading) on speed and accuracy with which relief information

can be extracted from hardcopy maps by subjects who were relatively experienced in map reading.

Subjects

Forty-eight male Army officers and NCOs who had had experience in

reading contour maps Pnd using them for land navigation were used as subjects. Approximately two-thirds of the subjects were "ranger-qualified"

and had therefore received advanced Army navigation training4

Procedure

j Subjects were tested in small qroups of up to eight subjects in a

group, each subject participating in one session. They were tested in

a large room with widely spaced tables..-one subject per table. Subjects

were assigned to particular map formats by altering the map format placed

at each seat and assigning seats randomly each day. Subjects were told

to work at their own rate of speed with intructions stating: "Work each

problem as quickly and accurately as you can. If you get tired, please

take a break or have a cup of coffee after you have finished the problem

Tired students won't give us a valid assessment of the different types of

relief portrayal." Subjects used stopwatches to determine the amount ok

time required to solve each problem and recorded both time and their answers on the answer sheet. As indicated previously, each subject worked

with on,y one format.

Results

The median times (min) required to solve the different types of problems are summarized in Table 2. Note that the times reported in Table 2

are for the blocks of questions contained on each of the map segments.

Flar example, in the landform identification problem* each subject had

four time scores, one for each of the four map segments used for this

problem (each map segment contained four questions). Using the four time

scores, the median was calculated for each subject* 'Me 1.0 min shown

14

..
in Table 1 for the contour version of the landform identification problem represents the mean of the median times for all subjects who took

the contour version of the map test. Analysis of these results using

a one-way analysis of variance showed significant differences for time

required to solve the identification of high-low areas on the map problem (p < .0 1). The time required to solve the Ridge-Valley Identification problem approached significance. Analysis of the mnedian times

required to solve the high-low problem using a Newman-Keuls procedure

showed that the solution times for maps supplemented with either layer

tints or shading were significantly less than those for unsupplemfented

contour line maps (p < .01 and p < .05' but were not significantly different from each other. Layer tints as a supplement to contour lines

produced the fastest solution times on seven of the eight problem types

although the differences were not statistically significant.

Table 2

Mean of Median Times Required to Answer Questions (min)

Shaded Layer

Contour relief tints

Landform identification 1.0 1.0 0.8

Ridge-valley identification 2.4 2.4 1,7

Slope identification 1.3 1.4 1.2

Identification of high-low

areas 4.2 3.1 2.5*

Spot elevation problems 4.5 4.1 34

Vertical profile identification 1.9 1.7 1.6

Terrain visualization 0$9 0.8 100

Defilade 2.7 2.5 1.9

*Sig. at 0.01 level using 1-way.ANOVAS,

Analysis of the mean accuracy scores using a one-way analysis of

variance showed siqnificant differences ine accuracy (p 4 .01) for the

spot eievation problem (44t Table 3).

Axnalysit of these mean accuracy Pcores for the spot elevation problems using the Newman-Xeuls procedure indicated that accuracy scores

were significan~tly higher for contour line maps and contour line maps

supplemented with layer tints than for contour line mapi supplemented

with s~hadin~g (p < .01), but were. not significantly different from each

other.,
Table 3

Mean Number of Correct Answers

Shaded Layer

Contour relief tints

Landform identification 13.6 12.4 13.1

Ridge-valley identification 23.8 20.6 25.2

Slope identification 12.1 10.3 11.7

Identification of high-low

areas 47.6 46.8 48.4

Spot elevation problems 23.1 16.6 22.6*

Vertical profile identification 8.5 6.8 7.7

Terrain visualization 9.5 8.4 9.1

Defilade 20.8 19.4 19.7

* Sig. at 0.01 level using 1-way ANOVA.

As indicated in the Description of the Test Construction section,

there were minor variations in placement of overprinted lines, points

and arrows due to slight differences in registration for the three relief

formats. The accuracy scores were corrected for possible effects of differences in registration for the three relief formats. The accuracy

scores were corrected for possible effects of differences in registration. Questions in which differences in registration might have affected

the answers were eliminated to produce corrected accuracy scores. This

alternate scoring procedure produced the same results for accuracy scores

as the original scoring procedure (p < 0.05).

It is also interesting to note that performance with shading was the

poorest (although not significantly so) on all of the eight subtests for

both corrected and uncorrected accuracy scores. If the scores for the

eight subtests were independent of each other, the probability of this

happening by chance would be (1/3)8 or 0.0002.

Taken together, the speed and accuracy scores indicate that for experienced individuals with at least a moderate amount of map reading and

land navigation experience, addition of layer tints to the contour lines

may enhance speed with whivh some types of relief information can be

extracted from the hardcopy map. Addition of shaded relief to contour

line maps, at least for the relatively high skill group that we tested,

does not decrease time necessary for extracting relief information from

hardcopy maps more than does addition of layer tints and actually may

cause a decrement in performance where, accuracy is concerned.

:i

- ,-.
Discussion and Conclusions

In a study similar to ours (Phillips et al., 1975) the authors compared contour line maps, contour line maps supplemented with shading,

layer tint maps and digital maps. They used questions concerning relative height, absolute height, base legibility (effect of relief portrayal

on extraction of non-relief information) and "visualization" (locate

steepest slope, defilade, matching portions of the maps to a plastic

model). As indicated previously, there are a number of differences between their test and our test including use of actual map stimuli; keeping the basic relief information constant in all map formats, and use-of

a systematic map sampling procedure for assigning map stimuli to the

different problems. In addition to these basic differences, their test

was run as a speed test and therefore scores reflect both speed and

accuracy. The digital maps proved to be superior for absolute height

mation content and consequently will not be considered further. Layer

tints proved best for two of the types of tasks, judging relative height

and "visualizing" the landscape. Contour line maps supplemented with

shading and contour line maps proved to be about the same for all problems. For judging absolute height, both contour line maps and contour

'A line maps supplemented with shading proved to be significantly better

than layer tint maps for one of the two map segments used in their study.

The results from our study are in agreement with those of Phillips et al.

in that gradient tints produced the best performance in ridge valley and

high-low problems which appear to correspond to some of Phillips et als.

visualisation and relative height problems. our results differ from

those of Phillips, et al* in that we found that both contour lines and

contour lines plus layer tints produced equivalent performance for judging absolute height (spot elevation problems); while adding shaded relief

to contour lines produced significantly less accurate performance.

Phillips et al. believe that this difficulty in use of layer tints

was due to errors made in matching tints on the maps with tints in the

key. Their layer tint maps differed from the ones used in our study in

+ [Jthat: (a) their tint boundaries were not numerically labelled for elevations and, (b) they used seven gradations of a single hue rather than

different colors which might be more easily discriminated.

Using 12-layer tints on their maps with colors ranging from green

through yellow and brown towhite for the highest elevation, Kempf and

M-ock (1969) found that addition of layer tints to contour lines significantly decreases time necessary to determine spot elevations from that

required when contour line maps are used. The different number of layer tints used (3-4 by ourselves and 12 by Kempf and Poock, 1969) may be responsible for the difference in results.

*11'11

5'±
Phillips et al. (1975) did not find any significant effect on extraction of non-relief information due to addition of shading or layer

* tints to contour lines. Kempf and Poock (1960) found that adding layer

tints to contour lines significantly increased time to find specific

grid coordinates. In another study Delucia (1972) found that adding

shading to contour lines significantly increased the time required for

srubjects to perform a location task.

In our test, use of four maps differing in elevation range and contour interval should decrease the possibility that the map stimuli used

in the test are unrepresentative of topographic maps currently in use.

This may not be true of the maps used by Phillips et al. (1975) which

were taken from a 1:2.4 million scale map of a portion of the Atlantic

Ocean bed. A significant question is "are there terrain related conditions (such as density of contour lines, types of landform, extent of

hydrographic features, variation in vegetation, etc.) which play a significant role in determining effectiveness of the supplementary relief

used?" Investigation of this question might help to provide a stronger

rationale for choosing between alternative possibilities of relief portrayal. A more parametric assessment of each type of relief format

might produce interesting cesults. However, the layer tints and shading

techniques used in our study are representative of those currently in

use and were chosen by map designers at the Engineering Topographic

Laboratory as being most appropriate.

The effects of subject population are easily overlooked when the

focus is on the topographic map. The information transmission characteristics vary with the subject population. Highly trained subjects

with high ability in pattern analysis might be able to see landforms

emerge from the pattern of the contour lines portraying terrain features; whereas, the contour lines may represent only clutter for moderately trained subjects with low ability in pattern analysis (Potash and

Jeffrey, 1978). The results of our experiment suggest that, for subjects

that have had training in reading contour lines and are at least moderately experienced in the use of contour line maps, addition of layer

tints can facilitate extraction of some types of basic relief informa1* tion. For this type of subject, the addition of shading does not facilitate performance above that produced by addition of layer tints and may

:1 result in a decrement in some type of tasks.

JI This test also may be used in more parametric studies than the

present one to assess the effectivenss of different versions of the same

relief format and the effects of differenL Pnvironmental conditions such

as illumination upon map legibility, The conflicting results on spot

elevation-related problems suggests that parametric work might produce

interesting results.

18

=I

................. ..Z, .' 2: ....... :: 2 .' ......... ... • ..' '" ......................... "....................I' " ...
This technique can be used for assessment of performance with alternative relief formats which do not have a common basis. However, that

is a somewhat more difficult problem, (for example, relief formats such

as shading plus spot elevation v. contour lines). If one wants to assess

the effect of different formats on perceptual accessibility of information, then care must be taken to make sure that information content of

the maps is constant. In the previous example, a sufficient number of

spot elevation points must be included so that the available quantitative

relief information approximates that provided by the contour lines. If

information content "typically" associated with different relief formats

is to be assessed, then one may want to contrast "representative" examples of the relief formats. In this case, differences in information

content in the map stimuli used in testing may be valid.

a--4

I,

. I "9 1
REFERENCES

DeLucia, A. The Effects of Shaded Relief on Map Information Accessibility. Cartographic Journal, 19 (1972), 14-18.

Hill, A. R. Cartographic Performance: An Evaluation of Orthophotomaps.

Royal College of Art, Final Technical Report, 1974.

Kempf, R. and Poock, G. Some Effects of Layer Tinting on Maps, Perceptual and Motor Skills, 29 (1969), 279-81.

Mappro, Test of New And Improved Map Products USACDED Experiment 72-15.

Final Report, Phase I. Fort Ord: Combat Developments Experimentation Command, 1973.

Potash, L. and Jeffrey, T. Factors in Design of Hardcopy Topographic

Maps. U.S. Army Research Institute, Technical Paper 284, January

1978.

Phillips, R., DeLucia, A. and Skelton, N. Objective Tests of the Legibility of Relief Maps, Cartographic Journal, 12 (1975), 39-46.

Skop, J. Investigation of User Requirements Pertinent to Relief Portrayal, Army Map Service, Corps of Engineers. Final Report, 1958.

Wheaton, G. R., Zavala, A. and Van Cott, H. P. Enhanced Photomap Evaluation Study. American Institutes for Research, Technical Report,

AIR-F-15-4, 67-TR, 1967.

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