GDA (Geologic Data Assistant), an ArcPad

extension for geologic mapping: Code,

prerequisites, and instructions

by Evan E. Thoms and Ralph A. Haugerud

Geological Survey Open-File Report 2006-1097

Use of product or trade names in this report does not constitute endorsement by the Geological Survey

Table of Contents

Introduction

Download GDA

What you need to know

Required hardware and software

Windows CE / PocketPC PDA

GPS unit

ArcPad

Software on the laptop or desktop

GDA

Outline of GDA

GDA data structure

Base map and compilation geology

Setup instructions

Initial setup

To start a new project

Each time you start ArcPad

Data Safety

Incorporating GDA data into a desktop GIS

Customization

References Cited

Introduction

GDA (Geologic Data Assistant) is an extension to ArcPad, a mobile mapping software program by

Environmental Systems Research Institute (ESRI) designed to run on personal digital assistant (PDA)

computers. GDA and ArcPad allow a PDA to replace the paper notebook and field map traditionally used for

geologic mapping. GDA allows easy collection of field data that include:

• Station location as determined by GPS, map inspection, or as a bearing and distance offset from an

existing station

• Map unit and related lithologies

• Outcrop characteristics

• Structural orientations
• Contacts, faults, and other linear features

• Information about samples

• Information about photographs

• Extended free-form text

• Sketches

• Miscellaneous map annotation

This report provides a link to downloadable code, describes the required hardware and software necessary to

use GDA, describes the GDA data structure, gives setup instructions for GDA, describes moving data from

GDA into a desktop GIS, and discusses customization of GDA. To use GDA efficiently will require an

intermediate knowledge of computer systems and, most importantly, good file management. GDA does not

have to be used in conjunction with ESRI's ArcMap, but knowledge of that program is useful for customizing

certain GDA files and viewing shapefiles. Haugerud and Thoms (2004) discuss rationales behind some of the

choices made in building GDA. 

Note that the GDA code includes HTML help files that discuss setup and use of the software. Much of this

report is copied from the GDA help files.

Download GDA

There are 2 downloadable GDA packages from which to choose depending on the intended host system.

• For installation on a Windows PC, download GDA_PC_Install.zip. This package contains the loose

files and a simple DOS batch file to copy them to the appropriate directories. This is also the package

to download for further development of GDA in ArcPad Application Builder. 

• For installation on a Windows CE device, download GDA_For_PPC.cab

Get a copy of this documentation as zipped html or PDF.

What you need to know

To use GDA, you should have some familiarity with your PDA, with ArcPad, and with some basic principles

of GIS.

First, use your PDA. Learn how to open programs and switch between them. Experiment with the several

different methods of text input, to find what works best for you. Learn how to change screen brightness. Poke

around in the system settings. Windows CE has changed significantly with each release. Our experience is

primarily with WinCE 3.0; if you are using a later version, some of our PDA-related advice may be wrong. 

Configuring the communications link between the PDA and an external GPS receiver can be challenging.

The instructions that work for our hardware and operating system are likely to be wrong for your setup. You

will have read your manuals (this may not help much) and experiment. 

Second, look through the ArcPad user manual (available here). Pay attention to the layer metaphor, the

notion of an active layer, the limits of ArcPad symbolization, and how a map projection can be defined. 

Third, you should have a basic understanding of map projections and datums. You should appreciate the

distinction between the contents of a spatial database and the symbolization of those contents on a map or
computer screen. 

Required hardware and software

Windows CE / PocketPC PDA

ArcPad, and thus GDA, runs on the Windows CE 3.0 (or greater) operating system, also known as the

PocketPC operating system. It can also be installed on Windows-based desktop, laptop, or tablet computers.

It does not work on Palm or Linux devices. Most WinCE computers are adequate. When selecting a PDA,

pay particular attention to display readability, communications capabilities, battery life, the quality of the

digitizer, memory capacity, and speed. We are currently using Hewlett-Packard iPAQs with 400MHz

processors, 64MB memory, and 240 x 320 pixel 16-bit color daylight-readable displays. 

Extra battery 

An extended-capacity battery, or an expansion pack with an additional battery, is desirable. You would like

to have enough power for continuous operation throughout a 14-hour field day. When using a GPS it is

especially useful to set your PDA to never shut off. One reason for this is simply efficiency, but the other is

that turning a PDA off without first disconnecting the com port often causes the PDA to lock up so that it can

only be reset with a soft reboot. The largest drains on the battery are the intensity of the backlight and the

length of time it is on, so set your backlight to dim to nothing after a short period of inactivity. 

Extra non-volatile memory

Use a Compact Flash card, Secure Digital card, or other non-volatile memory for mapping project

workspace. This provides storage for large raster images and guards against data loss when, inevitably, you

forget and let the PDA battery run down. We use expansion packs that provide both a Compact Flash slot and

an additional battery. Be aware that unless you store programs in a non-volatile space on your PDA, ArcPad

will evaporate from memory if the battery dies. As a backup in the field, keep a PC nearby from which you

can re-install ArcPad.

Bluetooth

Bluetooth (a short distance device-to-device radio protocol) is excellent for communication between the PDA

and a GPS unit. Cable connections between GPS and PDA are fragile, inconvenient, and hard to make

waterproof. 

Screen protector

Protect the PDA screen from abrasion with a self-adhesive replaceable plastic screen protector (check Office

Depot or a similar supplier.)

Case

The PDA probably won't survive a 4-ft drop onto bedrock. Get a rugged case that provides significant shock-
proofing. Consider third-party cases (such as Otterbox) as well as cases available through your PDA

manufacturer. Such cases can also be waterproof, with a clear vinyl window over the PDA screen--but if you

retain this window, omit any additional screen protector. 

3rd-party stylus

A third-party stylus with a pocket clip or lanyard is handy. Multifunction instruments that combine a stylus

with a pen or pencil (or both) are available for under fifteen dollars.

GPS unit

Standard recreational-grade GPS provides nominal XY accuracy of 10 meters (with averaging) at a cost of

$100-300. We find this sufficient. For increased accuracy use a WAAS-capable GPS unit, or a differential

GPS unit, at substantially greater cost. Note that ArcPad provides an excellent GPS display: all one needs is a

screenless GPS receiver that that can send standard NMEA 0183 signals to another device.

GPS satellites broadcast at a wavelength that does not pass through the human body, so a pocket is not a

good place from which to use a GPS unit. Instead, put it in the lid of a backpack, on the top of a staff

protruding from a pack, or fastened it to your hat. Another option is to use a small external antenna on a hat

(google on GPS Pathfinder Pocket Antenna Cap) while keeping the receiver in a pocket or on a belt clip (if

you can tolerate the necessary connecting cables). 

Communications between the GPS unit and PDA are a potential problem. If a cable connection is to be used

you may have to purchase appropriate cables for both GPS unit and PDA separately, and you may have to

join them with a male-to-male adapter and null modem connecter as well. See the ArcPad user manual for

good instructions on following this route. Duct tape will transform the cables and adapter into a single,

stronger, unit. The data-cable fitting on many PDAs is weak. One can mount the PDA in a rigid windowed

box with a short data cable that leads from the PDA to a more substantial fitting anchored to the box and

worry less about breaking the connector, but you will still be trussed up like Gulliver among the Lilliputians.

A wireless connection (e.g. Bluetooth, see above) is better. 

Compact flash card GPS units arguably provide the most robust connection. There are no cables, no risk of

losing the signal due to distance from the receiver (as there is with Bluetooth devices), and since the GPS

unit draws current from the PDA battery, there is no worry of having the unit die before your PDA does.

They can also be swapped in and out of the compact flash slot with fewer com port hassles than the

Bluetooth units. The main disadvantage with this method is that you are likely to lose the GPS signal as you

hold the PDA near your body while entering data. 

We use credit-card sized Bluetooth GPS receivers such as that sold by Socket Communications

(http://www.socketstore.com/product.asp?sku=2542622). These 16-channel receivers can be bought for less

than $230. They weigh 2 ounces and the replaceable and rechargeable battery lasts 9 hours, more than

adequate for working out of a vehicle with a cigarette-lighter recharger available. For a long day on foot

carry an extra battery or mobile recharger, such as the iPowerPak by Data Nation (http://www.datanation.com) or Mobile Power Pack by Socket.

In recent tests with a Bluetooth GPS unit and a Bluetooth-ready iPAQ h2200, we have found the Bluetooth

Manager to be much improved over older versions, causing us to lean even more strongly toward that system.
ArcPad

ArcPad is a simple GIS program for the PocketPC, optimized for collection and display of map information

while mobile. It has fewer symbolization and database capabilities than the average desktop GIS, can be

customized to a limited extent using XML and VBScript, and has an excellent GPS interface. 

ArcPad can be obtained from ESRI (http://www.esri.com/software/arcpad) for about $500. A free evaluation

copy that times out after 20 minutes may be downloaded from the web. GDA will not work with versions of

ArcPad earlier than 6.0.1 We are using ArcPad 6.0.3. We have not experimented with this version of GDA

on ArcPad 7. 

Third party file browser

The file browsing program that comes with the Windows CE, File Explorer, does not, by default, show file

extensions. Editing the registry to force file extensions to show is an option available to the advanced user,

but it is risky. The safest remedy is to install a third party program that shows extensions. PEFile, by Vieka,

is a cheap and reliable solution. Seeing file extensions is important because there are many files associated

with GDA which have names that differ only by their extensions. Many can be edited in a text editor on the

PDA by temporarily changing the extension to ‘.txt’.

Software on the laptop or desktop

ArcGIS/ArcView

ArcGIS or ArcView will make it easier to define symbolization, such as the colors of dots that correspond to

different map units. See the ArcPad manual for advice on this. (Note that you can also do this with a text

editor, carefully copying, pasting, and editing the .xml file for the layer. Colors are in RGB, 0..255 gamut for

each component. Search for "VALUEMAPRENDERER".) 

ArcGIS provides tools for reformatting data for digital base maps. You may need to reproject rasters to the

projection of your field project. ArcGIS will export an entire map project to ArcPad. Note that you may have

to tile large raster images to avoid the 50MB input-image size limit on the MrSID converter that is shipped

with ArcGIS. See the ArcPad documentation. 

You will almost certainly need ArcGIS or ArcView to make a completed geologic map from the data you

collect with GDA.

Excel (or OpenOffice) or Access

You will need to edit .dbf files that constitute some of the picklists. This is conveniently done on a PC with

Microsoft's Excel. The Calc program in OpenOffice.org works equally well. CDBF (google for it) works

well. Another solution is to create an Access database containing all of the picklist tables and export them as

needed in .dbf format. Let us know if you find a DBF editor that runs on a PDA!

Text editor

A text editor that works gracefully with plain ASCII files is handy for minor modifications of layer definition

(.apl) and VBScript (.vbs) files. On a Windows platform, WordPad and Notepad are fine. Many other
editors are available. Avoid using Microsoft Word because it may add hidden and extraneous formatting tags

that are not recognized by GDA.

GDA

Outline of GDA

GDA consists of 4 sets of files:

1) The GDA toolbar and events that occur when buttons on the toolbar are

tapped are defined by XML and VBScript files GDA_1.0.apa and GDA_1.0.vbs. From left to right,

icons when tapped effect the following:

• Make station layer active (tap location on screen to add station). Drop-down menu item for plotting a

station with bearing and distance from the currently selected station. 

• Add station at GPS location 

• Make geolines layer active (draw line on screen to add data). Drop-down menu item to draw a line

with a polyline tool. 

• Make mylar layer active (draw line on screen to add data) 

• Show Edit toolbar 

• Show GDA Help 

2) GDA modifies certain aspects of ArcPad's behavior with XML and VBScript files ArcPad.apx and

ArcPad.vbs. 

3) GDA help is provided by HTML help files in folder GDAHelp.

4) GDA data for a mapping project reside in a single user-designated project directory. Multiple mapping

projects require multiple project directories. Each project directory contains files for the 4 data layers
described below, a collection of .dbf files that define picklists, per-station files of notes and sketches that

may be created while using GDA, and an ArcPad.apm file (written by ArcPad each time work is saved)

that defines active layers, pathnames, current map extent, and controls some symbolization. Empty copies

of the data files are stored in a Templates directory that resides at the same directory level as the different

project directories. A mapping project directory will also commonly contain a projection file, a

subdirectory with base map layers, a subdirectory with compiled geologic data layers, and archive

subdirectories.

GDA data structure

GDA adds 4 editable data layers to a project: stations, structure, geolines, and mylar. Most data layers have 5

files: 3 files with extensions shp, dbf, and shx that constitute a shapefile, an ArcPad XML layerdefinition file with extension .apl, and--except for the mylar layer--a .vbs file that contains VBScript

code called by events defined in the layer definition file. 

Stations

Stations is the primary point data layer. Within it are recorded all station locations and much of the data

associated with them. Adding a new station brings up an edit form that controls almost all point attributes and

allows editing of associated tables for Samples, Photos, and the structure layer. Attributes of points in this

layer are:

Unit page (see image)

Attribute

Format

(type, N

bytes)

Editform

label

Definition Vocabulary

Where is vocabulary

defined?

STAID Char, 16 Form caption Station identifier Generated

automatically

from Geologist,

date, time

na

MAPUNIT Char, 30 Unit Geologic map unit

(formal or informal, may

be at any stratigraphic

level)

Open

Varies per

project

Self-updating

Default is value

at last station

Units_1.0.dbf

Corresponding

symbolization is

defined in

Stations_1.0.apl

CERTAINTY Char, 10 Certainty of

unit

identification

Open

Definite,

probable,

tentative

Stations_1.0.apl

HOWLOC Char, 10 How located How station is located Open

Inspection,

Offset, Other

Stations_1.0.apl
Set to GPS if

location by GPS

button

OCQUAL Char, 8 OC quality Nature of outcrop Open

Good, poor,

rubble, soil,

none

Stations_1.0.apl

OCDIAM Char, 5 OC min diam Minimum diameter of

outcrop

Open

0.1m, 0.5m, 1m,

2m, 5m

Stations_1.0.apl

SCALE Char, 8 Map scale 1: Denominator of map

scale at time station is

located

Automatically

generated

na

GEOLOGIST Char, 2 Geologist Used to calculate

StationID

Open Geologists_1.0.d

bf

DATUM

Char, 15 Not visible on

form

If the current station was

located by offset

coordinates from

another station, this field

stores the ID of that

'datum' station.

Automatically

generated

na

Lith page (see image)

LITH Char, 100 Lithology Short lithologic

description

Open

Self-updating

Units_1.0.dbf

MINGRNSZ Char, 10 Min grain

size

Use to describe the

minimum size of clasts,

crystals, blasts, etc. 

UddenWentworth scale.

GrainSizes_1.0.d

bf

MAXGRNSZ Char, 10 Max grain

size

Use to desctibe the

maximum size of clasts,

crystals, blasts, etc.

UddenWentworth scale.

GrainSizes_1.0.d

bf

The Lith page also has two buttons called ADD NOTE and ADD SKETCH which can be used to create and

edit text or graphics files, respectively, related to the current station. For instance, when the ADD NOTE

button is tapped during the attribution of a new station a file is created that is named with the station ID and

given a .txt extension. The file is then opened with the first line consisting of the current date and time and

you may add as much text as needed to describe the station or related attributes. During successive visits to

the station, tapping the ADD NOTE button will open the original file and prepend the date and time of the

visit.
The file extensions associated with these two buttons are .txt (ADD NOTE) and .psw (ADD SKETCH).

By default, WinCE devices will use Pocket Notepad to open files with a .txt extension and Pocket Word to

open those with a .psw extension. We chose Pocket Word for the sketch files only because it has a

rudimentary drawing toolbar and it is available on all WinCE devices. There are a number of graphics

programs designed for PDAs that will far exceed Pocket Word's drawing capabilities for a reasonable price.

If you install one, you will need to change the GDA code so that the files created by the ADD SKETCH

button are given an appropriate extension. Open Stations_1.0.vbs with a simple text editor such as

Notepad and search for 'SketchPath' within the AddSketch subroutine. Change the string ".psw" to the

extension associated with the graphics program you want to use.

Other pages of the Stations form allow editing of subsidiary tables (dbf files) for Samples and Photos. Fields

in these tables and the associated entries in the Stations edit form are shown in the tables below.

Sample page (see image)

Attribute

Format

(type, N

bytes)

Editform label Definition Vocabulary

Where is

vocabulary stored?

STAID Char, 16 not shown ID of station at which

the sample was

collected.

Automatically

generated

na

SAMPID Char, 16 Listed in Samples

from this station

SampleID Automatically

generated

na

PURPOSE Char, 30 Purpose Type of analysis to be

performed on sample

Open

Self-updating

Samptype.dbf

Photo page (see image)

Attribute

Format

(type, N

bytes)

Editform label Definition Vocabulary

Where is

vocabulary stored?

STAID Char, 16 not shown ID of station at

which the photo

was taken.

Automatically

generated

na

PHOTOID Char, 15 Listed in Photos

from this

station

With care, can

match camera

filename

Calculated from Prefix

and No. Selfincrementing

na

TOPIC Char, 100 Topic Subject of photo Open

No pick list

na
WIDTH Char, 8 Width Width of field of

view

Open

No pick list

na

DIRECTION Char, 5 Direction View direction Open

N,NE,E,SE,S,SW,W,

NW,down

Stations_1.0.

apl

With properly configured symbolization (see Symbolization), points in the Stations layer can be shown as

dots whose color corresponds to MAPUNIT. 

Structure

Structure is a point layer for storing and plotting orientation data (bedding, foliation, lineation, etc.) Such

data are stored in a layer separate from the Stations layer so that they can be plotted. A point must first be

added to the Stations layer before orientation measurements can be recorded. Structure data are added from

the Str page of the Stations form (see image). 

As each measurement is added to the Structure layer, GDA programmatically copies the coordinates of the

station point to the Structure layer. Multiple structure measurements may be added at a single station.

Features of the Structure layer are described in the following table:

Attribute

Format

(type, N

bytes)

Editform

label

Definition Vocabulary

Where is vocabulary

stored?

STAID Char, 16 not shown ID of station at which the

structural observation

was made.

Automatically

generated

na

STYPE Char, 30 Type Open StrucTypes_1.0.dbf

Corresponding

symbolization is defined in

Structure_1.0.apl

QUALITY Char, 1 Poor

observation

(checkbox)

Closed

Unchecked

(default)=F

Checked=T

na

AZI Char, 3 Strike/Trend Azimuth (strike, trend) in

degrees, 0=North,

clockwise

Follows right-hand rule:

for N-S strike, AZI=0 for

E dip, AZI=180 for W

dip

0..360 na
INC Char, 3 Dip/Plunge Inclination (dip, plunge)

in degrees, 0=horizontal,

90=vertical (down),

-90=vertical (up)

-90..90 na

DATE_ Date, 8 not visible Date of measurement. System date na

The table below shows the contents of StrucTypes_1.0.dbf as it is distributed in GDA. The Text field

shows the value that will be stored within the STYPE field. Note that Structure_1.0.apl contains

instructions for STYPEs in addition to those listed below; these can be added to StrucTypes_1.0.dbf

and will be symbolized. Addition of other values to StrucTypes_1.0.dbf will require that you update

the symbology defined in Structure_1.0.apl (see Symbolization).

TEXT

upright bedding

overturned bedding

bedding no top

bedding, horizontal

joint

fault

slickenlines

striae

foliation

schistosity

cleavage

lineation

stretching L

mineral L

intersection L

foliation, horizontal
dike

fold hinge

Geolines

Geolines is a line layer for contacts, faults, shorelines, and other linear features. Attributes of lines in this

layer and their characteristics are:

Attribute

Format

(type, N

bytes)

Editform Definition Vocabulary

Where is

vocabulary

stored?

DATETIME Char, 24 Date and time of

observation

Automatically

generated

na

LTYPE Char, 30 LineType Geologic line type Open Geolines_1.0.apl

PRECISION Char, 20 Precision

(m)

Precision of line

location

Open

1, 2, 5, 10, 25, 50, 100

default is 0, should be

understood as

NODATA

Geolines_1.0.apl

SCALE Char, 20 Map scale

1:

Denominator of map

scale at which line is

digitized

Automatically

generated

na

The table below shows the contents of LineTypes_1.0.dbf as they are distributed GDA. The

LINETYPE field shows the value that will be stored in the LTYPE field. If these values are changed or more

are added and you wish to have new values symbolized properly, you will have to update the symbology (see

Symbolization).

LINETYPE

contact

fault

outcrop limit

scratch boundary
till bed

peat bed

ash bed.

bedding trace

fold

anticline

syncline

marker bed

dike

vein

scarp

Mylar

Mylar is a layer of unattributed lines, included to provide flexibility. Use Mylar for map ornamentation, text

written directly on the map, or other annotation. Note that in most cases any information in this layer must

later be translated into a form that can be queried by machine.

Base map and compilation geology

ArcPad allows GDA to use a wide variety of base materials, including previous geologic data. The primary

limitation is symbolization. Only one raster layer may be used at a time, as ArcPad does not support

transparency.

Setup instructions.

Initial setup

Establish an ActiveSync connection between the PC and the PDA.

Install ArcPad on the PC:

Use the default installation folder suggested by the setup wizard, i.e. ‘ C:\Program Files\Arcpad’
On the PC, Start>Programs>ArcPad>Install ArcPad application for Windows CE

On the PC, Start>Programs>ArcPad>Install ArcPad font for Windows CE

On the PC, Start>Programs>ArcPad>Install VBScript Runtime Library for Windows CE

Install GDA:

Both the .bat and .cab files assume you installed ArcPad in the default directory!

Download the appropriate GDA package for your system and unzip the file.

For installation on the PC, double-click on GDA_PC_Install.bat.

For installation on the PDA, copy GDA_For_PPC.cab file to any folder, make a copy (.cab files

disappear once unzipped), and double-tap the file.

Choose ‘No’ to any dialogs asking you to retry installation of a font file.

The default locations after installation are shown below. If you have chosen to install ArcPad in a nondefault folder, you will have to move the files from the unzipped GDA_PC_Install.zip file manually.

Location on PC Location on PDA

C:\Program Files\ArcPad\AppletFiles

GDA_1.0.apa

GDA_1.0.vbs

\Program Files\ArcPad\Applets

GDA_1.0.apa

GDA_1.0.vbs

C:\Program Files\ArcPad\SystemFiles

ArcPad.apx

ArcPad.vbs

\Program Files\ArcPad\System

ArcPad.apx

ArcPad.vbs

My Documents\GDAProjects\

GDATemplates\

\My Documents\

GDATemplates\

C:\WINDOWS (or WINNT)\Fonts

esri_7.ttf

\Windows\Fonts

arial.ttf

esri_7.ttf (ESRI Geology

After installation on a PC, move the My Documents\GDAProjects\Templates folder to another drive

and folder if you wish; the other folders must remain within the ArcPad installation folder.

After installation on a PDA, move the My Documents\GDATemplates folder to a non-volatile storage

card and make a copy of it for each project.

Configure PDA to communicate with Bluetooth GPS unit.

These are general instructions for making contact with a Socket Bluetooth GPS unit on an
internally enabled bluetooth PDA. If you use a different GPS unit these instructions may not

apply.

Make sure the GPS unit is fully charged.

Power on the GPS unit. The status LED will blink blue.

Power on the PDA.

Turn PDA Bluetooth radio ON (Tap blue and black icon in the lower right corner of PDA screen).

Tap Bluetooth icon (now blue and white) and open Bluetooth Manager.

Perfom a Bluetooth device discovery to find the GPS unit.

Pair and bond with the the Bluetooth GPS unit. Use the passkey 0183 if prompted. You only need to

discover, bond with, and pair with the GPS unit the first time you use it with your PDA.

Start ArcPad and check the settings below before attempting to enable the GPS.

Configure ArcPad

Start ArcPad.

Open ArcPad Options (crossed wrench and hammer: top toolbar, 2nd icon from right, select Options...)

and configure Protocol and GPS pages. 

With the Socket GPS communicating via internal Bluetooth on an IPAQ H3900, appropriate

settings are:

Protocol page

Protocol: NMEA 0183

GPS Datum: WGS84

Use Height in Datum Transform:

GPS Initialization String:

GPS page

Port: COM8

Baud: 4800

Parity: None

RTS Control: enable

DTR Control: enable

Infra Red:

Data Bits: 8

Stop Bits: 1

Monitor CTS:

Monitor DSR:

Log:

Show GPS Activity in System Tray:

IMPORTANT: On the Capture page enable averaging. 10 points is a good number. This is necessary

for certain VB script routines to be fired properly, but it is also good GPS practice.

Configure other GPS quality parameters and warnings as needed on the Quality, Capture, and Alerts

pages. For instance, you can tell ArcPad to reject any GPS fixes with a PDOP (position dilution of

precision) greater than 6 (4 is considered excellent and you may routinely see PDOP values better than

3. Never accept a PDOP greater than 8).
IMPORTANT: On the Paths page, set the Default Maps & Data Path to the project folder your data

are in.

Save the map as ArcPad.apm within the default data folder. This map will now be opened by default

when ArcPad is started.

Using GPS with ArcPad

Check that ArcPad is receiving valid NMEA strings by going to the GPS dropdown menu and

choosing GPS Debug. If you see nothing, then something is configured incorrectly.

Always disable the GPS through ArcPad's GPS menu before you turn ArcPad off.

Likewise, disconnect the PDA from the GPS through the Bluetooth manager before turning the PDA

off.

Failing to disconnect properly from the GPS will usually lock up the COM port which only a soft

reboot will clear.

To start a new project

A mapping project has a common geographic area, a common geologic vocabulary, and a single map

projection and datum. Many geologists will work on only one project. Others might have several, perhaps

including a project mapping glacial deposits in western Washington in the Washington State Plane North

feet-NAD83 coordinate system and a project mapping late Cenozoic rocks and deposits in northwest Oregon

in the UTM10 meters-NAD27 coordinate system. 

Directory structure

For each new project (new area, new projection, and (or) new theme), create a directory on your storage card

by making a copy of Templates and renaming it to <NewProj>, where <NewProj> is a relatively short

version of the project name. Within <NewProj>, create subdirectories for base layers and compilation

geology as you see fit.. With two projects named BremE and Wen, the Storage Card directory tree would be :

\Storage Card\

BremE\

base\

old_geol\

WASPN83.prj

files for geolines, mylar, stations, structure

Units_1.0.dbf, StrucTypes_1.0.dbf, etc.

Wen\

base\

old_geol\

UTM10NAD27.prj

files for geolines, mylar, stations, structure

Units_1.0.dbf, StrucTypes_1.0.dbf, etc.

Templates\ 
ArcPad.apm

ArcPad maintains a default data path (that is, a default directory). If a map-description file named

ArcPad.apm is present in the default data path, that map will be opened when ArcPad is started. 

Start ArcPad. Go to Tools>Options>Paths and change the default data path to your current map-project

directory. Open a new map. Add base layers, Stations, Structure, Geolines, and Mylar to the map. Set the

scales at which various layers plot, if you desire. Save the map--this will write an ArcPad.apm file to the

map-project directory. ArcPad.apm defines the layers present in an map, the area shown on the display when

the map is opened, and some symbolization.

You can re-save ArcPad.apm whenever you wish, and it may be useful to re-save before you exit ArcPad,

though this is not necessary. It is best to overwrite the current version--don't Save As a new file. 

Base materials

For convenience, keep all base materials in a subdirectory <NewProj>/Base. Possible base materials include:

• Standard USGS DRGs

• Shaded-relief images, calculated from standard USGS DEMs or high-resolution data

• Orthophotos

• Vector contours

• Digital assessor's parcel maps

Note that only one raster file can be shown at a time, as ArcPad does not support transparent rasters. If you

want to display a raster composite, for example colored unit polygons over shaded relief, you must explicitly

create this image in ArcGIS and export it to a suitable image-file format.

Raster images must all be in the same projection. Convert vector layers to the same projection as well;

ArcPad won't reproject on the fly.

MrSID compression is desirable, both to create image pyramids and to reduce overall file size. Experiment to

find the appropriate degree of compression. We find 10-15x works well. The 50Mb limit for single files input

to the MrSID converter in ArcGIS may require that some input files be chopped into smaller tiles. 

Map projection

ArcPad needs to know the project map projection and the GPS cannot be enabled without one. 

1) If you export the project from ArcGIS, a projection file (*.prj) should be created. Install this in the

project directory.

2) You can put any prj.adf file (from within a coverage or grid – rename it to .prj) or .prj file

(associated with a shapefile or from the ArcGIS\Coordinate Systems folder) into the project workspace.

When you add a new layer that does not have an explicitly defined projection, you will be asked if you wish

to use this projection. 

3) You can assign a projection to each map layer with the Map Projection button (top right icon on the

Layers dialog) in ArcPad.
ArcPad will not reproject data to a common projection for a map project. All layers must have the same

projection,.

All layers need not have a separately defined projection. Indeed, GDA takes advantage of this feature, and

leaves the default geologic data layers with projections undefined, so that each new project may pick up its

projection from an associated base layer or a freestanding projection file.

Your choice of projection will usually be forced by the projection of the raster layers (DRGs, shaded-relief

images, DOQQs) used for a map base. In a given mapping project, such rasters should all be in the same

projection. 

Vocabularies

You will need to edit Units_1.0.dbf to establish an initial unit vocabulary for a new project. Open a

copy of this file in Excel, OpenOffice Calc, Access, or similar, select and delete existing values, add new

values, and re-arrange values. Note that "LITH" need not be specified. Save and move the modified copy of

the file to the project workspace. 

If symbolization is based on any vocabulary values you create or edit, you will need to change the symbology

element within the shapefile’s .apl file. You may do this manually from within a text editor if you wish,

but it is much easier to use the method outlined below.

Symbolization

You can create symbology for a new project with ArcGIS or ArcView:

Included in the ArcPad install folder are two folders called apTools3 and apTools8. In these folders are

extensions with export tools for use in either ArcView 3.x or ArcGIS 8.x (and 9.x).

To install apTools8.dll for ArcGIS: 

• Go to Start>Run and type: regsvr32 "C:\Program Files\ArcPad\apTools8\apTools8.dll" (or whatever

the full pathname is to the file). Be sure you have administrator rights to your computer or the dll will

not install properly. 

• In ArcMap, go to Tools>Customize

• Click on the Commands tab and click on Add from file. Browse to apTools8.dll and select it. 

• Four commands will appear in the right-hand window. Drag Export Symbology to any toolbar. 

To install apTools3.avx for ArcView 3.x:

• Move all files in apTools3 to C:\ESRI\AV_GIS30\ARCVIEW\EXT32 (or the appropriate

directory).

• In ArcView, go to File>Extensions and turn the extension on. 

Add the shapefile for which you want to create symbology to an ArcMap or ArcView map

Create a feature for every possible attribute and symbolize it.

Points can be symbolized with any true type font character, lines can be symbolized with
different thicknesses and color only, and polygons can be symbolized with solid opaque

colors only.

Click on the Export Symbology tool you just installed.

If you are setting the symbology for a point shapefile, open the .apl file for the shapefile that was just

created and search for <TRUETYPEMARKERSYMBOL. Note the font being used for each occurrence of

that XML element.

Drag and drop those fonts from your PC's fonts directory into the fonts directory on your PDA. 

Rotating truetype symbols

To rotate point symbols according to an attribute value (eg Azimuth from the Structure shapefile):

Open the .apl file for the shapefile you are dealing with and search for VALUEMAPRENDERER.

Add these attributes to that XML element:

rotationfield="MYROTATIONFIELD" rotationtype="geographic"

Each time you start ArcPad

Each time you start ArcPad you will have to re-start communication between the PDA and GPS unit. With

WinCE 3.0 and the Socket Bluetooth GPS,

Power on the GPS unit

Power on the PDA

Turn PDA Bluetooth radio ON (Tap blue and black icon in lower-right corner of PDA screen.)

Tap Bluetooth icon (now blue and white) and open Bluetooth Manager

Tap the entry for the GPS unit (EMTAC BTGPS 22..) to establish communication

Close Bluetooth Manager.

Once GDA is installed and the first map is saved as \Storage Card\<ProjName>\ArcPad.apm, ArcPad will

restart with GDA up and running in the most recent project and map extent. 

When we start GDA we routinely make GPS Active, enable GPS Tracklog, and--using the Layers form--

make the GPS Tracklog invisible.

Data safety

Saving

Whenever you tap OK on the Station edit form, or tap ADD on the Structure, Photos, and Samples pages,

data are written to memory. You need not tap the Save icon on the top toolbar.

The Save icon (or Save Map on the File menu) saves the current map extent, the list of map layers, and any

special instructions you've defined with the Layers forms. Tapping the Save icon every now and then doesn't

hurt--and mostly isn't necessary. 
Data not written to files

We have had problems with data not being written to dbf files. We think these problems have occurred

because of mixed versions (e.g., an old .apl file and a newer .dbf format) or corrupt XML in a layer definition

(.apl) file. 

If GDA is properly configured and you pay attention, failure to record data will be evident immediately. (A)

Set up Station point symbolization to reflect MAPUNIT. Are the dots the right color? (B) Using the layer

dialog, label each station point with MAPUNIT or the like. If you don't see MAPUNIT written beside a new

station, data were not recorded. (C) Can you see structure symbols? If not, why? (D) Label each structure

point with its INC. 

If data are not written to dbf files, delete the feature and re-enter it. If data are still not saved, make paper

notes. 

If you find that data are not being written to dbf files, and particularly if you can establish the conditions that

cause this to happen, please let us know. 

Archiving

At intervals, copy all data files to an archive folder, copy this folder to a PC, and burn it to CD-ROM for

safekeeping. Data files include

Geolines_1.0.dbf, Geolines_1.0.shp, Geolines_1.0.shx

Mylar_1.0.dbf, Mylar_1.0.shp, Mylar_1.0.shx

Stations_1.0.dbf, Stations_1.0.shp, Stations_1.0.shx

Structure_1.0.dbf, Structure_1.0.shp, Structure_1.0.shx

Tracklog.dbf, Tracklog.shp, Tracklog.shx

Photos_1.0.dbf

Samples_1.0.dbf

all note (.txt) and sketch files

any projection files

It may be useful to put a copy of Units_1.0.dbf in the archive folder, to better understand the

MAPUNIT and LITH vocabularies that were suggested to the mapper. It will also be useful to put copies of

all digital photographs into the archive folder. We suggest naming the archive folder with the geologists'

initials and date of archiving, (a truncated version of a station ID), such as 06_0322ET. The directory

structure of the PDA storage card may then look like this:

/Storage Card/

<MyProject>/

base/

old_geol/

06_0320ET/

06_0322ET/

Arcpad.apm

Geolines_1.0.apl

...

Units_1.0.dbf

Templates/

Here are two strategies for archiving, each with its advantages and disadvantages: (1) You can COPY data

files to the new archive folder. Grow a single, evolving set of data files for the project. Archive folders grow

steadily larger and each archive folder supplants its predecessor. At any time, a single set of shapefiles

encompasses all of the your data for the project. An advantage of this approach is that earlier observations are
readily accessible. 

(2) Or you can MOVE all current data files to the new archive folder. Replace them with blank shapefiles

from the Templates directory. Keep the current Units_1.0.dbf. Move/copy appropriate photo files and note

files to the archive folder. Data are not duplicated in multiple archive folders. An advantage of this approach

is that database files remain small for better performance. A disadvantage is that several sets of archived

shapefiles must be concatenated to capture the entire project. 

Turn GDA databases into a narrative

The Python script gda2html.py (located in the Utilities folder) will turn a GDA project folder, or an

archive folder, into a narrative in HTML format that is easily read, edited, and printed. Most computers with

ArcGIS have Python available as part of the ArcGIS installation. To use this script you will have to locate

and install modules dbf and image; see instructions within file gda2html.py. 

Incorporating GDA data into a desktop GIS

To move data into a desktop GIS, we have found it simplest to archive a project, then copy the entire archive

directory to the computer that hosts the GIS. The archive directory on the PDA may then be deleted, or left

for reference during further mapping. If the working directory on the PDA is on a storage card, you can

temporarily mount the storage card on the GIS host for fast drag-and-drop transfer. 

How GDA data are incorporated into a compilation project in the desktop GIS will depend strongly on the

data structure of the desktop project. We suggest these guidelines:

• Keep all GDA data in a "FieldData" directory within the compilation project workspace

• Create a script for transferring data from archive subdirectories within the FieldData directory to the

appropriate data layers in the compilation project. Think about how to avoid incorporating data from a

single archive more than once! 

• We find it useful to incorporate almost all of the GDA Stations and Structure layers into the

corresponding layers in the GIS compilation project. Geolines and mylar are used primarily as

backdrops for digitizing linework in the compilation project. 

• Symbolize the stations layer in the GIS with dots the colored to match MapUnit. Plot (on screen or

paper) these dots on top of unit-colored polygons from the units-contacts-faults compilation layer.

This allows visual confirmation that the compiled geology matches field observations. One can also

intersect the stations layer with units-contacts-faults polygons and search the resulting point coverage

for mismatches.

Customization

We wrote GDA in the course of our employment with the U.S. Geological Survey. It is not subject to US

copyright. You have an unrestricted right to modify and redistribute GDA code. However, we request that, as

a matter of courtesy:

1. If you redistribute GDA code, please include the file Copying.htm (in the folder Applets/GDAHelp/),
with appropriate modifications. 

2. If you modify and redistribute GDA code, please retain notice of our authorship and identify your

contributions. 

3. If you modify and redistribute GDA code, please rename all files (e.g., change the version number)

and make corresponding changes to internal file references. This will minimize errors associated with

mixing files from different versions of GDA. See Utilities/set_version.py for help.

4. If you redistribute GDA code, with or without modifications, please allow others to freely modify and

redistribute it also. 

Customize with a DBF editor

During use--perhaps on a daily basis--you may find that Units_1.0.dbf should be edited for clarity and

performance. We particularly find it useful to edit values in the LITH field, reduce the number of rows that

correspond to differing values of LITH, and re-order rows. StrucTypes_1.0.dbf, SampType.dbf,

and Geologists_1.0.dbf can be similarly edited. 

Customize with ArcView or ArcGIS`

For new projects, and as projects evolve, symbolization will have to be created and modified. This can be

done on a PC with ArcView or ArcGIS, and new symbology exported to layer definition (.apl) files that

are then copied to the PDA. See Symbolization, above. 

Customize by editing XML and VBS files with a text editor

All of GDA's behavior can be modified by editing the appropriate XML and VBS files. Use a text editor that

works gracefully with plain ASCII, not Microsoft Word! Modifying VBS files requires knowledge of VBS

and a clear understanding of the internals of GDA. We don't recommend this for most GDA users. 

Modifying XML files to change picklists, to change vocabularies from open to closed, and to modify some

symbolization is relatively straightforward. Use existing XML as a guide to format. Copy, paste, and modify.

Experiment! Be sure to keep an unmodified copy. To test for corrupt XML, open the modified file with a

browser such as Firefox (Microsoft's Internet Explorer 6 doesn't display XML). If the file will not display, it

probably won't work. 

Note that if you modify symbolization by directly editing the layer definition (.apl) file, the EXACT

statements within VALUEMAPRENDERER must be in strict ASCII order, followed by a single OTHER

statement. If the EXACT statements are not properly ordered, the symbolization will not work as you expect.

Customize using ArcPad Application Builder

If you wish to significantly modify forms, change or add attributes, or add new tables, we suggest working

with ArcPad Application Builder. This is expensive. We found that the $1,500 cost of Application Builder is

cheaper than the time required to learn VBScript and the innards of ArcPad. Expect to spend a lot of time

reading ESRI's User Forums.
References Cited

Haugerud, R.A., and Thoms, E.E., 2004, Geologic Data Assistant (GDA): an ArcPad extension for geologic

mapping , in Soller, D.R., editor, Digital Mapping Techniques '04: U.S. Geological Survey Open-File Report

04-1451, http://pubs.usgs.gov/of/2004/1451/haugerud/index.html.