This example shows you how to add a custom projection in Geoserver.
The projection parameters need to be provided as a WKT definition, so first thing is to write down a proper definition, such as:

PROJCS["NAD83 / Austin",
  GEOGCS["NAD83",
    DATUM["North_American_Datum_1983",
      SPHEROID["GRS 1980", 6378137.0, 298.257222101],
      TOWGS84[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]],
    PRIMEM["Greenwich", 0.0],
    UNIT["degree", 0.017453292519943295],
    AXIS["Lon", EAST],
    AXIS["Lat", NORTH]],
  PROJECTION["Lambert_Conformal_Conic_2SP"],
  PARAMETER["central_meridian", -100.333333333333],
  PARAMETER["latitude_of_origin", 29.6666666666667],
  PARAMETER["standard_parallel_1", 31.883333333333297],
  PARAMETER["false_easting", 2296583.333333],
  PARAMETER["false_northing", 9842500.0],
  PARAMETER["standard_parallel_2", 30.1166666666667],
  UNIT["m", 1.0],
  AXIS["x", EAST],
  AXIS["y", NORTH],
  AUTHORITY["EPSG","100002"]]

NOTE: the above has been formatted for readability, you'll have to provide it on single line instead, or put a backslash character at the end of every line except the last one.

1. Go into your geoserver data directory, that will be referred as $datadir in the rest of the document. If you don't know where it is, have a look at the Geoserver logs, on start-up you'll see a big message reporting something like:

   ----------------------------------
   - GEOSERVER_DATA_DIR: C:\progetti\geoserver\src\1.5.x\configuration\release
   ----------------------------------

2. Go into the $datadir/user_projections folder, and open the epsg.properties file. If you don't have one, don't worry, create the $datadir/user_projection folder and then an empty text file name epsg.properties in it.
3. Insert the above WKT (well known text) for the projection at the end of file (on a single line or with backslash characters, here it's formatted for readability):

   100002=PROJCS["NAD83 / Austin", \
     GEOGCS["NAD83", \
       DATUM["North_American_Datum_1983", \
         SPHEROID["GRS 1980", 6378137.0, 298.257222101], \
         TOWGS84[0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]], \
       PRIMEM["Greenwich", 0.0], \
       UNIT["degree", 0.017453292519943295], \
       AXIS["Lon", EAST], \
       AXIS["Lat", NORTH]], \
     PROJECTION["Lambert_Conformal_Conic_2SP"], \
     PARAMETER["central_meridian", -100.333333333333], \
     PARAMETER["latitude_of_origin", 29.6666666666667], \
     PARAMETER["standard_parallel_1", 31.883333333333297], \
     PARAMETER["false_easting", 2296583.333333], \
     PARAMETER["false_northing", 9842500.0], \
     PARAMETER["standard_parallel_2", 30.1166666666667], \
     UNIT["m", 1.0], \
     AXIS["x", EAST], \
     AXIS["y", NORTH], \
     AUTHORITY["EPSG","100002"]]

4. Save the file
5. Restart geoserver
6. Check the WKT has been properly parsed. You should see the newly-defined projection by going to http://localhost:8080/geoserver/srsHelp.do.
7. If the projection wasn't listed, examine the console output for any errors related to parsing the WKT for your projection (the first time I insterted the WKT I had an extra comma):

   tried to parse projection EPSG:100002 but couldnt!

Note the missing 's' at point 2:   "create the $datadir/user_projection folder" should read " create the $datadir/user_projections folder". Miles Posted by miles at Jun 21, 2007 00:55