A first step in planning a project is to determine what
coordinate system to use.
About this task
You can plant projects that use spatial data and use one of the 2,000
coordinate systems that are included with Db2® Spatial Extender or a custom one
that was created by another users.
To find out more about these coordinate systems, and to determine what other coordinate systems
are included with Db2 Spatial Extender, and what (if
any) coordinate systems have been created by other users, consult the DB2SE.ST_COORDINATE_SYSTEMS
catalog view.
Procedure
To determine what coordinate system to use:
-
Review existing coordinate systems that
are included with Db2 Spatial Extender and use the
corresponding spatial reference system that is based on the coordinate system of your choice.
The most used coordinate systems are:
- GCS_NORTH_AMERICAN_1983. Use this coordinate system when you need to define locations in the
United States; for example:
- When you import spatial data for the United States from the Spatial Map Data available for
download.
- A coordinate system that Db2 Spatial Extender refers to as
Unspecified. Use this coordinate system when:
- You need to define locations that have no direct relationship to the earth's surface; for
example, locations of offices within an office building or locations of shelves within a storage
room.
- You can define these locations in terms of positive coordinates that include few or no decimal
values.
-
If you cannot find an existing coordinate systems in Db2 Spatial Extender, you can create
one as
follows:
- Run an application that invokes the DB2SE.ST_CREATE_COORDSYS procedure.
Creating a coordinate system is rarely necessary. You need to also create an spatial reference
system based on the new coordinate system.