There is a pressing need for geographic information systems which can manage spatially-referenced data, that perform certain types of spatially-oriented processing, and that are current and comprehensive. Polygon overlay and grid cell information systems access data for selected areas, but their data files are time consuming to generate and frequently costly to process. Updating of land use changes for such systems may become prohibitively expensive. In response to the present dilemma, a system is presented that makes use of digital image processing techniques to interface existing geocoded data sets and information management systems with thematic maps and remotely sensed imagery. The basic premise is that geocoded data sets can be referenced to a raster scan that is equivalent to a grid cell data set.

Several technical problems have been overcome to achieve a workable system. First, digital image file handling, image manipulation, and image processing capabilities must be provided. Second, image data must be registered or indexed to spatially-referenced tabular data so that processing steps which involve both types can operate. Third, a data interface must be provided between the different datatypes so that the results of processing can be represented. Finally, image processing analogs must be developed for existing geo-base file computational steps (e.g., overlay, aggregation, cross tabulation, etc.). The system is now in use on a test basis.

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