GEOLOGICAL MAPPING WITH A TABLET PC; LESSONS FROM THE LLANO UPLIFT, CENTRAL TEXAS

We applied a relatively new approach to geologic mapping that involved an outdoor tabletPC, GPS receiver and GIS software in an area of meter-scale and larger folds of Precambrian marbles in the Llano uplift, central Texas. In addition to producing a structural map, our goal was to evaluate the feasibility and usefulness of this technology in a field situation where detailed mapping had already been completed, and to gauge the extent to which an inexperienced user might become proficient in a short period of time. We contrast these results with those derived from similar experiments with a mapping-grade GPS receiver (Trimble GeoXT), and from stand-alone, hand-held GPS receivers (Garmin eTrex and Trimble GeoExplorer) used in conjunction with gridded paper maps.

Equipment for tabletPC mapping included an Xplore Technologies iX104RV, Windows XP Tablet edition and ArcGIS and ArcPad software, a Garmin eTrex Vista GPS receiver, serial to USB cable and software, and spare batteries. The Trimble GeoXT ran Windows CE, with GPScorrect and ArcPad 6 Software. Digital base maps (DRGs, DOQs and vector topography) were obtained online from the Texas Natural Resources Information Service. Vector data files from earlier GPS/digital mapping in the area were also incorporated.

Preliminary results indicate the promise of a TabletPC as a standard mapping tool. The principle advantages of a TabletPC over mapping-grade and stand-alone GPS receivers, in order of importance, are: 1. Larger screen size 2. An inductive digitizer pen 3. Standard Windows and GIS software 4. Customization of GIS editing tools 5. Capture of handwritten notes and sketches. Ongoing studies are underway to determine the most efficient means of field GIS editing and data collection.