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ARC /INFO provides some tools for developing user interfaces, but the capabilities of this environ- <br />ment are limited. At this time, no source code can be obtained for ARC/INFO, and only a limited set <br />of library routines can be licensed at an additional cost from the user's license. This significantly <br />limits the ability to incorporate spatial manipulation features into a modeling effort using a GUI. <br />GRASS <br />GRASS is a public domain raster -based GIS that has been developed by the U.S. Army Corps of <br />Engineers. The main advantages for using GRASS for modeling and data analysis are: <br />• INFORMIX can be used to store attribute information for GRASS coverages. <br />• The code for GRASS is public domain and has a large and active user community that <br />continues to develop improvements to the system. <br />• The system continues to be developed and maintained by the U.S. Army Corps of Engineers <br />Construction Engineering Research Laboratory (CERL) in Champaign, Illinois. <br />• The GRASS system has been used extensively by the Integrated Decision Support (IDS) <br />Group at Colorado State University and has proved to be a very valuable tool for spatial <br />modeling. <br />• A set of libraries is provided with the GRASS software. The user can incorporate functions <br />directly into a GUI design, as well as design new spatial analysis routines, if required. <br />Converting from ARC /INFO to GRASS <br />The following process is used to export ARC/INFO coverages to GRASS: <br />1. Coverages should be built as lines, polygons, or points in ARC/INFO. <br />2. While in "arc," run the command "ungenerate." For arcs such as streams, run this command <br />with the option, "line" (create a file with extension .1 in). For polygons such as soils, run <br />this command for the options "line" and "points" (create two files with extensions .1 in <br />and . pts). <br />Example to export the polygon coverage soils <br />ungenerate line soils soils.lin <br />ungenerate point soils soils.pts <br />3. Go to the INFO module in ARC and select the . aat (for a line topology cover) or the .pat <br />(for a polygon coverage) file to export for the associated ID, category, and text with the <br />ungenerated file. <br />Example: <br />SEL SOILS.PAT <br />ITEMS {to display items to be used with the INFO commands DISP and <br />PRINT, to generate the text associated file with the ungenerated files} <br />,4275 05.01.95 G 1.06 -2 CSU IDS <br />