AN ARCHITECTURE FOR DIGITAL GEOLOGIC DATA COLLECTION WITH ARCPAD GIS SOFTWARE

The USGS Pacific Northwest Corridor Mapping Project is developing and using customized tools and data entry forms for collecting digital geologic field data with ESRI's ArcPad and ArcPad Application Builder GIS software. We have two related goals in mind with the development of this architecture: to primarily, but not exclusively, collect those data necessary for symbolizing a geologic map and that those data conform to the schema of parent ESRI geodatabases.

Forms and custom toolbars are stored as XML files and event-triggered macros are stored as VBscript files. Data are stored in (1) ESRI shapefiles, (2) programmatically created files that are linked to a field station ID, and (3) stand-alone DBF files. Editing sessions in ArcPad are facilitated through a custom toolbar that controls which layers are editable in order to maintain certain one-to-many linking attributes. The forms and procedures work on any set of point and line shapefiles that conform to our chosen schema, thereby enabling multiple projects to use them.

Custom applets (mini-applications that run in ArcPad) written in VBscript are in use that (1) format the entry of measured section data, (2) present cascading picklists queried from large but heirarchically organized flat-files, (3) write delimited text files for input into other programs, and that (4) plot points and polylines from laser rangefinder data.

We have found the use of these mobile GIS solutions to be most useful for the collection of easily binned and strongly typed data such as feature locations, station IDs, sample locations, and files inputted from external devices, to name only a few. The time required to build forms complex and flexible enough to hold most of the data a field geologist will collect in a general mapping project may be prohibitive. Projects with specific and limited types of data to collect may benefit the most from this technology.