GEOLOGIC MAP PRODUCTION IN THE DIGITAL WORLD - COMBINING THE BEST OF OLD AND NEW TECHNOLOGIES

The huge increase in computing power and decrease in software and hardware costs over the past decade have created a vast array of new digital technologies. These greatly enhance the speed of production of accurate detailed geologic maps, allowing quick conversion of maps into a variety of digital and printed formats. However, these technologies, if employed incorrectly, can actually increase production time, create endless frustration, or worst of all, lead to the production of vast quantities of inaccurate or poor quality map data. It is imperative to use “the right tool for the right job.” Over the past decade, the Utah Geological Survey has experimented with a large variety of new field and laboratory digital map production methods -- most successfully, but some with less satisfactory results. Successful technologies include digital and analytical photogrammetry, ruggedized field tablet pcs, heads-up and auto-vectorizing software, computer-aided design software, and GIS software. We have found that a mix of old and new field mapping and office production methods generally produce the best quality data in the least amount of time. For example, digital high-resolution orthophotoquadrangles and raster base maps are excellent tools for controlling placement of geologic data in digital compilation modes. However, raw images require careful processing to optimize on-screen resolution, and to maximize legibility of printed maps. Conversion of digital orthophotoquad images sandwiched with raster base maps to color formats provides a medium for manual compilation of field mapping. After manual compilation of field mapping, this tightly controlled base map can be filtered to remove base map information, leaving only easily vectorized geologic data. Fit of geologic data to base maps, particularly data compiled from older maps, requires careful registration and manipulation to maintain accuracy and consistency with base map contours, and in many cases remapping unresolvable areas. Adaptation with meticulous quality control is the key to quality map production.