Spatial data models • Raster – exhaustive regular or irregular partitioning of space – associated with the field view – location-based • Vector – points, lines, areas – associated with the object view – object-based
Jan 19, 2016
Spatial data models• Raster
– exhaustive regular or irregular partitioning of space– associated with the field view– location-based
• Vector– points, lines, areas– associated with the object view– object-based
Spatial data models
Vector data models
• An object (as opposed to field or location) viewpoint of space
• represent geographic entities as discrete objects composed of points, lines, and polygons
Vector data models
• Spaghetti vector data model– each point, line, or polygon that represents a
geographic entity is stored as a record in a file that consists of that entity’s ID and a list of coordinates that define it’s location (or the coordinate space that it occupies)
Vector data models
• Spaghetti vector data model
– relationships among objects are implied
Vector data models
• Spaghetti vector data model– advantages
• simple
• efficient for display and plotting
– disadvantages• inefficient for most types of spatial analysis
Vector data models
• Vector topologic data model
– composed of points, lines, and polygons– node: a point at the intersection of two or more
lines– in addition to coordinate locations, the
topologic relationships between geometric features are explicitly recorded
Vector data models
• Vector topologic data model
Vector data models
• Vector topologic data model
Vector data models• Vector topologic data model: GBF/DIME
Vector data models
• Vector topologic data model: POLYVRT (hierarchical data structure)
Vector data models• Freeman - Hoffman chain-code for compacting vector storage
Vector data model
• TIN: Triangulated Irregular Network
Vector data model
TIN: Triangulated
Irregular Network
Vector data model• TIN: Triangulated Irregular Network
Vector data model
• Hybrid vs. integrated systems for vector data models– A hybrid system stores spatial data in one type
of data model and the attribute data in another data model that is often an existing commercial non-spatial database
– An integrated system manages both spatial and attribute data using the same data model
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B
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ID Length KeyA 5 1B 6 2C 6 2D 7 1E 9 1F 9 3
Key Name Length1 Main St. 212 Elm St. 123 Spruce St. 9