Spatial DBMS Spatial 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