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CRDSS <br />TASK MEMORANDUM 1.06 -2 <br />Spatial Database <br />Geographic Information Systems for the CRDSS <br />1.0 ISSUE <br />This task memorandum describes the use of geographic information systems (GIS) in the CRDSS. <br />2.0 DISCUSSION /ANALYSIS <br />There are two primary functions for the use of GIS as part of the CRDSS: <br />• Generating a spatial database <br />• Using GIS for modeling and analysis <br />These two functions are different and can best be satisfied by using two different GIS tools. The GIS <br />program ARC /INFO is used to develop and edit spatial data. The GIS program GRASS is used for <br />modeling and data analysis. In this project, the attributes for spatial data are stored in the INFORMIX <br />portion of the CRDSS Database. This allows the data to be maintained in only one location. <br />ARC /INFO <br />The ARC /INFO program is primarily a vector -based system with a strong capacity for editing and <br />developing spatial data. <br />The main advantages of ARC /INFO for developing and editing spatial data are listed below: <br />ARC /INFO is a well supported commercial package with excellent functionality. <br />Data sources routinely provide data in ARC /INFO export file format. <br />ARC /INFO contains excellent routines for digitizing and creating /editing coverages. <br />The State primarily uses ARC /INFO. <br />The main disadvantages of using ARC /INFO for modeling and data analysis as part of a large <br />decision support system (DSS) are listed below: <br />• ARC /INFO is proprietary and multiple licenses would need to be purchased, which can be <br />expensive. <br />ARC /INFO cannot be seamlessly included in a graphical user interface (GUI). <br />• The internal structure for data storage requires significantly more disk storage (sometimes as <br />much as 10 times more) than GRASS. <br />,4275 05.01.95 1 1.06 -2 CSU IDs <br />