The JPEG files were opened in R2V (Figure 1), and a process was used to eliminate the colors, preserving just the black line features from the author's original mapping. The maps were scanned and saved as 300-dpi, 24-bit, color JPEG files. The source maps were paper topographic base maps on which the author had inked lines and labels and polygons were hand colored in pencil. OVERVIEW OF METHODSRecently the UGS vectorized 32 7.5-minute geologic quadrangles to compile a 30 x 60 minute quadrangle.
WHEN TO CONVERT RASTER TO VECTOR ARCGIS SOFTWARE
This paper summarizes the autovectorization process using R2V from Able Software Corporation. Although these applications are also capable of heads-up digitizing and interactive vectorizing (line following), the focus of this test was to autovectorize the entire map. We downloaded trial versions of the software and vectorized the same map using each application. There was no real scientific method to our evaluation. In an effort to minimize our table digitizing and increase efficiency and positional accuracy, we evaluated five commercially available vectorizing programs. The software we used made workers frustrated with the amount of time required to vectorize a map, and the editing tools were inefficient and not user friendly. The Mapping Program of the Utah Geological Survey (UGS) has attempted to scan and vectorize geologic maps of various types with mixed results. Geologic maps do not vectorize well with many of these programs. Most vectorizing software is optimized for the archival of old engineering drawings, architectural plans, and historical documents, where most lines meet at right angles.
However, the ability of applications to vectorize scanned (raster) maps varies widely. BrownĮ-mail: INTRODUCTIONRaster to vector conversion of geologic maps has proven to be a valuable asset in the creation of a GIS database. Geological Survey Open-File Report 02-370 Raster to Vector Conversion of Geologic Maps:Using R2V from Able Software Corporation By Kent D. USGS OFR 02-370: Raster to Vector Conversion of Geologic Maps Digital Mapping Techniques '02 - Workshop Proceedings
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