Deciding whether to use a default spatial reference system or create a new system

After you determine what coordinate system to use, you are ready to provide a spatial reference system that suits the coordinate data that you are working with.

Answer the following questions to determine whether you can use one of the default spatial reference systems:

1. Does the coordinate system on which the default spatial reference system is based cover the geographic area that you are working with? These coordinate systems are shown in Spatial reference systems supplied with IBM Spatial Support for Db2 for z/OS.
2. Do the conversion factors associated with one of the default spatial reference systems work with your coordinate data?
   IBM Spatial Support for Db2 for z/OS uses offset values and scale factors to convert the coordinate data that you provide to positive integers. To determine if your coordinate data works with the given offset values and scale factors for one of the default spatial reference systems:

   1. Review the information in Conversion factors that transform coordinate data into integers.
   2. Look at how these factors are defined for the default spatial reference systems. If, after applying the offset value to the minimum X and Y coordinates, these coordinates are not both greater than 0, you must create a new spatial reference system and define the offsets yourself. For more information about how to create a new spatial reference system, see Creating a spatial reference system.
3. Does the data that you are working with include height and depth coordinates (Z coordinates) or measures (M coordinates)?
   If you are working with Z or M coordinates, you might need to create a new spatial reference system with Z or M offsets and scale factors suitable to your data.
4. If the existing spatial reference systems do not work with your data, you need to create a spatial reference system.
   For more information, see Creating a spatial reference system.