Defining Spatial Information

This chapter provides an introduction to spatial information - how do we describe the position, shape, and orientation of objects in space generally, and in specific terms, features on the surface of the earth?

Different types of geometry are introduced - Points, LineStrings, and Polygons - and examples are given to illustrate the sorts of features on the earth that these geometries are commonly used to represent.

The chapter then examines different types of spatial reference system, and explains how such systems can be used to unambiguously describe the position of each point in a geometry representation. Each component of a spatial reference system is introduced in turn (coordinate system, datum, unit of measurement, projection), and their relevance to spatial data explained.

I'll show you the sys.spatial_reference_systems table, which records details of all geodetic spatial reference systems supported by SQL Server 2008, and explain the significance of each column of data.