[Geoserver-users] Datum conversion (google earth)

Hi!

I have some data in Oracle SDO tables that are in GaussKruger zone 5
projection (based on Bessel1841 ellipsoid). Data in SDO tables have no SRS
information.
Since I need custom Bursa-Wolf parameters, I have defined a custom SRS in
epsg.properties file as follows:

100025=PROJCS["HR_GK_5",GEOGCS["GCS_Bessel_1841",DATUM["HAC_Bessel_1841",SPHEROID["Bessel
1841",6377397.155,299.1528128,AUTHORITY["EPSG","7004"]],TOWGS84[514.0,
155.49, 507.05, -5.613852, -3.675670, 11.466815,
2.091013]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",5500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",15.0],PARAMETER["Scale_Factor",0.9999],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]

However, when viewing the data in Google Earth (using the KML link from
geoserver), the data has an offset. I've done some manual calculation and
came up with the fact that the data is thought if it were in WGS84 datum -
or in other words only the inverse transverse mercator operation is
performed, but not the datum conversion as well. Why is that? Am I missing
something?
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Krwoloq ha scritto:

Hi!

I have some data in Oracle SDO tables that are in GaussKruger zone 5
projection (based on Bessel1841 ellipsoid). Data in SDO tables have no SRS
information.
Since I need custom Bursa-Wolf parameters, I have defined a custom SRS in
epsg.properties file as follows:

100025=PROJCS["HR_GK_5",GEOGCS["GCS_Bessel_1841",DATUM["HAC_Bessel_1841",SPHEROID["Bessel
1841",6377397.155,299.1528128,AUTHORITY["EPSG","7004"]],TOWGS84[514.0,
155.49, 507.05, -5.613852, -3.675670, 11.466815,
2.091013]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",5500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",15.0],PARAMETER["Scale_Factor",0.9999],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]

However, when viewing the data in Google Earth (using the KML link from
geoserver), the data has an offset. I've done some manual calculation and
came up with the fact that the data is thought if it were in WGS84 datum -
or in other words only the inverse transverse mercator operation is
performed, but not the datum conversion as well. Why is that? Am I missing
something?

How did you configure your feature type? In particular, did you declare
you custom SRS and used the "force declared" projection policy?
If so, it can you share a bit of your data so that I can reproduce
and investigate?

Cheers
Andrea

--
Andrea Aime
OpenGeo - http://opengeo.org
Expert service straight from the developers.