CONVERTING AN UNPUBLISHED GEOLOGIC MAP TO A PUBLISHED VECTOR-BASED IMAGE

Digitizing geologic quadrangle maps to produce raster images, and then converting them to vector images, allows for easier access, modification, and distribution. It also provides the capability of querying the data. Superimposing the geological line data and point data onto a set of digitized topography, drainage, and culture produces a multilayered digital file of a geologic map on a standard topographic map base. A digital map of The Rensselaer Falls NY 7.5" quadrangle, located in the northwest Adirondacks was produced in this way. The map was created from a scanned image (TGA file) of the hardcopy geologic map using ABICAS™, a menu-driven DOS program. Scanning, file transfer and manipulation, vectorizing (automatically and semi-automatically), attributing, and compilation were the major steps in converting the hardcopy map to digital format. The finished product will be integrated into the state's digital map database and be made available via the Geological Survey web page. Excess files, such as digital line graphs (DLGs), points, lines, and area data in Atlas GIS format (BNAs), and digital exchange format (DXF), created while vectorizing can be exported and used in other map information programs, such as Geographical Information Systems (GIS). This project was completed in association with and supervised by John J. Thomas of Skidmore College and Yngvar Isachsen of the New York State Museum. Critical assistance in programming and digitizing was also provided by Russel Ambrosiak of the United States Geological Survey.