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