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CRDSS <br />TASK MEMORANDUM 2.03-02 <br />Conversion from Arc/Info Coverages to GRASS <br />1.0ISSUE <br />The CRDSS Spatial Database contains Geographic Information System (GIS) capabilities and spatial data in <br />Arc/Info and GRASS (Geographic Resources Analysis Support System) formats. The GIS capabilities are presented <br />in the Visual Data Browser (VDB) Interface or the CU Model as described in the CRDSS Users? Manual. <br />This Task Memoradna will describe the process of converting Arc/Info coverages to GRASS for use in individual <br />CRDSS models. During this process some error is incured during this process primarily because of the conversion of <br />linear based data to raster or grid based systems. Task Memoradum 2.03-03 quantifies the error associated with this <br />process for some of the primary coverages for CRDSS. For most coverages this error is less than 0.01%. <br />2.0DISCUSSION/ANALYSIS <br />The GIS Arc/Info is used for the development of spatial data. The Arc/Info coverages can then be converted into a <br />GRASS format that can be used within the VDB Interface <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 />To open arc: <br />>> arc <br />2.While in ?arc? run the command ?ungenerate.? For arcs such as streams, run this command with the option, <br />?line? (create a file with extension *.lin). For polygons such as soils, run this command for the options ?line? <br />and ?points? (create two files with extensions *.lin and *.pts). <br />To export a polygon coverage: <br />Arc: ungenerate line soils_awc soils_awc.lin <br />Arc: ungenerate point soils_awc soils_awc.pts <br />3.Go to the INFO module into ARC and select the *.aat (for a line coverage) or the *.pat (for a polygon coverage) <br />file to export for the associated ID, category, and text with the ungenerated file. <br />Export text file: <br />Arc: INFO <br />CENTER USER NAME> ARC <br />ENTER COMMAND > SEL SOILS_AWC.PAT <br /> 866 RECORD(S) SELECTED <br />View items available in coverage: <br />ENTER COMMAND > ITEMS <br />Page 1 <br />01/03/97 2.03-02 - Lange <br />