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Spatial DBMSSpatial Database Management Systems
Introduction
SDBMS is a database system with additional capabilities for handling spatial data.
• Spatial Objects
• Consist of points, lines, surfaces, volumes and higher dimension objects that are used in applications of computer-aided design, cartography, geographic information systems.
• Spatial Data
• The values of the objects’ spatial attributes: length, configuration, perimeter, area, volume, etc.
• Spatial Databases
• A collection of spatial and non-spatial data that is interrelated, of data descriptions and links between data
March 2002
April 2004
Functionality
• Spatial data is comprised of objects in multi-dimensional space
• Spatial Indexing
• Retrieving objects in a particular area without scanning the entire space
• Spatial Joins
• Efficient algorithms for joining multiple spatial objects
Raster and Vector Data
• Two very different types of data
• Vector is spit into three primary types:
• polygon, line, point
• Raster data represents the fourth type of feature: surfaces
• Eg: thematic data, spectral data, and pictures (imagery)
Spatial Relationships
• Topological relationships
• Eg: adjacent, in, touch, equal, cover, overlap, disjoint, etc.
• Direction relationships
• Eg: above, below, north of, southeast of, etc.
• Metric relationships
• Eg: distance, size, perimeter, etc.
Querying
• Spatial Selection
• Eg: “All rivers in Arkansas” or “All rivers within 50 miles of Little Rock”
• Spatial Join
• Eg: “For each river in Arkansas, find all cities within 20 miles”
Indexing
• Organized so that only parts of the objects need to be examined to answer a query
• Data stored as either points or polygons
• Query types for points:
• All points within a rectangle, point closest to query point, find points matching x in increasing distance from query point
• Query types for polygons:
• Intersection
• Containment