DATA CAPTURE IN THE FIELD FOR GEOLOGIC MAPS AND OTHER APPLICATIONS

We have been working for the last 4 years on developing techniques for digital data capture while in the field. Our efforts have been concentrated in two areas: geologic maps made directly in geographic information systems programs (GIS) and photogrammetric treatment of vertical and inaccessible outcrops. We have written scripts for ArcView GIS that allow for making geologic maps easily in the field. The main components are 1) point and line drawing tools (modified for easier error checking) and 2) a set of classification dialogs. The drawing tools are for creating the basic elements of the geologic map, such as contacts and structural orientation information. The classification dialogs allow the mapper to enter detailed information about structures directly into a GIS (e.g., the nature and significance of a contact). The classification scheme follows a very simple data model presented in Walker et al. (1996, March, GSAToday). Using this method we are able to create an integrated map database in the field. The GIS scripts and field-hardened laptops have been used with great success by University of Kansas students in field camps for the last three years (for results see Walker and Black, 2000, November, Geotimes). Publication of digital maps is easy to do over the World Wide Web (see http://geomaps.geo.ukans.edu for examples) and may become possible soon through GSA.

We have also used photogrammetric techniques to map outcrops. Outcrop surfaces that are generally inaccessible can be mapped by creating orthophotographs. This is done by photographing the area of interest with a calibrated camera and adding as many control points as possible. The photographs and points are then placed in a coordinate system amenable to whatever photogrammetry package is being used (we have generally applied the Orthomax module of ERDAS Imagine) and orthorectified. In this way quantitative values, such as section measurements, can be extracted.