6 Coordinate Systems (Spatial Reference Systems)

This chapter describes in detail the Oracle Spatial coordinate system support.

This support was introduced in Coordinate System. You can store and manipulate SDO_GEOMETRY objects in a variety of coordinate systems.

For reference information about coordinate system transformation functions and procedures in the MDSYS.SDO_CS package, see SDO_CS Package (Coordinate System Transformation) .

• Terms and Concepts
  This topic explains important terms and concepts related to coordinate system support in Oracle Spatial.
• Geodetic Coordinate Support
  Effective with Oracle9i, Spatial provides a rational and complete treatment of geodetic coordinates.
• Local Coordinate Support
  Spatial provides a level of support for local coordinate systems.
• EPSG Model and Spatial
  The Oracle Spatial coordinate system support is based on, but is not always identical to, the European Petroleum Survey Group (EPSG) data model and dataset.
• Three-Dimensional Coordinate Reference System Support
  The Oracle Spatial support for three-dimensional coordinate reference systems complies with the EPSG model.
• TFM_PLAN Object Type
  The object type TFM_PLAN is used is by several SDO_CS package subprograms to specify a transformation plan.
• Coordinate Systems Data Structures
  The coordinate systems functions and procedures use information provided in the tables and views supplied with Oracle Spatial. The tables and views are part of the MDSYS schema; however, public synonyms are defined, so you do not need to specify MDSYS. before the table or view name.
• Legacy Tables and Views
  In releases of Spatial before 10.2, the coordinate systems functions and procedures used information provided in the following tables, some of which have new names or are now views instead of tables.
• Creating a User-Defined Coordinate Reference System
  If the coordinate systems supplied by Oracle are not sufficient for your needs, you can create user-defined coordinate reference systems.
• Notes and Restrictions with Coordinate Systems Support
  The following notes and restrictions apply to coordinate systems support in the current release of Oracle Spatial.
• U.S. National Grid Support
  The U.S. National Grid is a point coordinate representation using a single alphanumeric coordinate (for example, 18SUJ2348316806479498).
• Geohash Support
  A geohash is a standard String encoding of a longitude/latitude point.
• Google Maps Considerations
  Google Maps uses spherical math in its projections, as opposed to the ellipsoidal math used by Oracle Spatial. This difference can lead to inconsistencies in applications, such as when overlaying a map based on Google Maps with a map based on an Oracle Spatial ellipsoidal projection.
• Example of Coordinate System Transformation
  This topic presents a simplified example that uses coordinate system transformation functions and procedures.