VIRTUAL FIELD ASSISTANT: TERRAIN ANALYSIS IN THE FIELD WITH GEOLOGICALLY FOCUSED GIS ON A SMARTPHONE OR TABLET

Smartphones and tablets have processing power and graphics capabilities unimaginable at the start of the personal computer revolution in the 1980’s: more RAM, bigger hard disks, better screens, and integration with orientation sensors and GPS positioning. While handheld devices can access the web, many field geoscientists operate in remote locations that have no internet access, or it will be cost prohibitive. For those users, downloading data to the handheld and processing it locally provides a viable option that fits in a pocket or field vest. The Nexus 7 provides a good example of such a device: 20.0 x 11.4 x 0.9 cm in size, weighing 289 gm, with a 1200x1920 screen, and 16 GB of RAM for $150. The tablet is significantly smaller and cheaper than the ruggedized tablets previously used for field GIS, and most users are already carrying around a cell phone of comparable size. The Nexus 7 can download air photos or satellite imagery, existing maps, digital elevation models, lidar point clouds, and vector overlays for several days operation on foot; the downloaded data could be easily swapped out from a laptop to cover larger field areas. The Nexus has 4 cores, and by using multi-threaded software the tablet can approach the processing power of a single-threaded laptop. The advantages of doing computerized terrain analysis in the field, with the ability to directly compare the results to reality, make slight performance penalties acceptable. The analytic and display capabilities of the MICRODEM GIS freeware, with a number of specialized functions for geology and geomorphometery, now run on both Android and Windows. The user interface must be modified for the handheld devices, which will probably never have all the capabilities of desktop GIS, but will concentrate on those options a user can best use in the field. The following functions have been optimized for multiple cores and run under Android and Windows: display DEM maps and lidar point clouds, overlay imagery, compute new grids, compute zonal terrain attributes, do viewsheds and line of sight profiles, and produce block and perspective 3D views. Combining traditional terrain analysis, tagged field photographs, Brunton-like computation of dip and strike, and direct data entry, the smart phone or tablet becomes a complete virtual field assistant.