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Models and Structures of ArcGIS UML and Data Modeling Elements. Longley et al., 8 (2/e) Zeiler, chs. 4, 5, and 12 Review Zeiler ch. 1. Models for GIS. representation of reality --> model GIS itself is based on a model of complexity GIS is used to model complexity
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Models and Structures of ArcGISUML and Data Modeling Elements Longley et al., 8 (2/e) Zeiler, chs. 4, 5, and 12 Review Zeiler ch. 1
Models for GIS • representation of reality --> model • GIS itself is based on a model of complexity • GIS is used to model complexity • full representation of reality? • data model = limited representation of reality • a discretization or partitioning of space • finite, discrete nature of computing devices
Data Model • representation of information about the process • FIELD … “grid” • OBJECT … “isoline” • FIELD or OBJECT … “geo-relational” • “Delauney triangulation” (alternative)
3 Data Models • geo-relational coverage (object view; from classic ArcInfo) • geo-relational shapefile (object view; from ArcView) • geodatabase (object-oriented; new in ArcGIS)
A B Georelational Data Model:“Classic” ArcInfo and ArcView Arc Info command line interface Unix, NT, Windows ArcView as interface
ArcInfo Coverage as a Data Structure Image courtesy of Louisville/Jefferson County Information Consortium, Kentucky
Data Structure • not tied to process at all • concerned simply with what can be computed and what can’t • the way in which the data model is representedin the GIS • DEM for field model • contour for isoline model (variation on object) • TIN for Delauney triangulation model • coverages, shapefiles for geo-relational • geodatabase for OO geodatabase
Data Structures • ArcInfo coverages • ArcView shapefiles • ArcInfo grids, USGS DEMs • Images (e.g., georeferenced tiffs) • TINs • Geodatabases
yellow coverage green shapefile gray geodatabase ArcGIS 9 Icons( Zeiler, pp. 65-71 )
Geodatabase If coverages are apples … and shapefiles are oranges … The Geodatabase can be your grocery bag…
Elements of the Geodatabase • Feature Datasets • Feature Classes • Relationship classes • Geometric Networks • Domains • Ranges • Coded Values • Topology • Tables • Metadata • And More!!!
Geodatabase • Features and attributes as objects • Relationships among features • Validation or editing rules, behaviors • “Container” for • Vector, raster, tabular data • Relationships • Topology Object Table MS-Office
ESRI Data Models for Geodatabase Templates Pre-designed schema (skeleton) of • Objects -Feature classes -Tables • Relationships • Domains • Rules
Why Data Models & Gdb Templates? • Work with users & partners on practical design projects • Build useful ready to load geodatabases • Continue the process with feedback from real projects • Support & encourage standards