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CRDSS <br />TASK MEMORANDUM 1.05-16 <br />Study of System Integration Issues <br />GUI - General Map Displays <br />1.0 ISSUE <br />A general map display tool for the CRDSS is required both to display information for modeling <br />needs, and as a browse tool for viewing data in the database. It is envisioned that this map display <br />tool could be developed in such a way that its features are available to all development efforts <br />through a library of routines. <br />2.0 DISCUSSION/ANALYSIS <br />A map display/browser will be developed to display general spatial information (e.g., irrigated land <br />and water district boundaries), as well as serving as the foundation of more sophisticated displays. <br />The tool will also be used as a front end to the tabular database, whereby tabular data are selected by <br />selecting a spatial object such as a reservoir symbol. This tool is envisioned for situations in which <br />the types of information to be displayed are well known. It is not envisioned as a tool for <br />manipulating spatial data as a developer or database administrator would do. <br />The display tool will be made available as a self-contained module which can be included in other <br />programs as well as being available as a stand-alone viewer. The display widget will consequently <br />have a great deal of intelligence built into it, such that the tool can be included in any application <br />simply by activating the tool. To do this, the tool will depend on underlying libraries of routines: (1) <br />the low-level DMI library used to access the CRDSS database, (2) a library or libraries to access GIS <br />information (including GRASS routines), and (3) a library of higher-level database display widgets. <br />Based on the recommendations provided in Task Memorandum 1.06-2, it is envisioned that <br />ARC/INFO be the GIS tool used for collecting and editing spatial data. After these tasks have been <br />completed, GRASS will be used for the interactive portion of the system so that a seamless interface <br />occurs. <br />GIS access will be provided by both a low-level display library such as the GRASS library, and a <br />utility library that is more specific to the CRDSS project and its data organization. For example, the <br />GRASS library will contain the standard GRASS routines to display data. The utility library will <br />contain routines that know how to access the data to be displayed by the GRASS lib rary. It is <br />proposed that ARC/INFO be used as the administration tool for GIS data but that GRASS be used for <br />straightforward display purposes. This approach will allow display applications built on the public <br />domain GRASS software to be distributed without large costs and will also allow applications to be <br />more compact. <br />The DMI library is discussed in Task Memorandum 1.05-8, and will be used to request tabular data <br />from the database. It is assumed that the data in the database are grouped reasonably well. <br />Consequently, the data object that is returned from the database will roughly match the contents of <br />1 <br />A275 05.10.94 1.05-16 Malers <br />