Understanding and Using Geometry, Projections and Spatial Reference Systems in ArcGIS

—David Burrows, Melita Kennedy and Robert Juergens

The ArcGIS geometry system defines the shape of geodatabase features and provides ways to create and edit them and relate them to each other. The spatial reference system provides a location for them. Projections and datum transformations correctly place features from different data sources onto the same map. Understanding these systems allows you to correctly and efficiently use many of the other ArcObjects APIs. These systems are also relevant to Web application developers, such as those using the geometry service. This session introduces the set of geometry and spatial reference objects that are available, including how the properties of spatial reference objects control the precision of coordinates stored in geodatabases. Several common situations where you will use geometries and spatial references in cooperation with other APIs, such as the geodatabase, editor, and geometry service APIs, will be shown.