Spatial DBMSSpatial Database Management Systems

IntroductionSDBMS 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