Hi, I have a problem with re-projection. My layer is in oracle table,
in ED50(EPSG:23030). When I request wms map to Geoserver, and specify
the SRS to EPSG:4326 (to represent into googlemaps), the
transformation is about 80 meters from the correct location. I view
the SRS info for 23030 with srsHelp.do, and the bursa wolf parameters:
TOWGS84[-157.89, -17.16, -78.41, 2.118, 2.697, -1.434, -1.1097046576093785]
¿Geoserver can re-project between two diferent ellipsoids? ¿This
parameters are correct?, I find other parameters searching into
mailing-list-archives. ¿Can I modify this parameters?¿Where?
Thanks in advanced...
F.Zuriaga
Fernando Zuriaga ha scritto:
Hi, I have a problem with re-projection. My layer is in oracle table,
in ED50(EPSG:23030). When I request wms map to Geoserver, and
specify the SRS to EPSG:4326 (to represent into googlemaps), the transformation is about 80 meters from the correct location. I view the SRS info for 23030 with srsHelp.do, and the bursa wolf
parameters:
TOWGS84[-157.89, -17.16, -78.41, 2.118, 2.697, -1.434,
-1.1097046576093785]
¿Geoserver can re-project between two diferent ellipsoids?
Yes, it can.
¿This parameters are correct?, I find other parameters searching into
mailing-list-archives.
Well, these parameters come from the official EPSG database. Yet, for
some areas the EPSG database defines more than one set of TOWGS84
coefficients, and our code extracts just one of them... we should add
ways to extract alternate ones too, but for the moment we don't have
the resources to attack this problem (it seems simple, but in fact it
would require various changes to both GeoServer and GeoTools).
¿Can I modify this parameters?¿Where?
There is a way to alter the EPSG database directly, but its very
complicated.
If you want to try out with other parameters I suggest you create your
own custom projection in the
geoserver_data_dir/user_projections/epsg.properties file, using
a code of your invention (but not used by the official epsg database),
and setting different parameters. Some instructions here:
http://docs.codehaus.org/display/GEOSDOC/Custom+projection+definition+in+Geoserver+1.5.0+(onwards)
Let me know how it goes, 80 meters seems a whole lot to me (I was
expecting something around 5-10 meters). Also, today I fixed an issue
in CRS handling which may affect this behaviour... you may want to try
out this nightly build: http://geo.openplans.org/nightly/1.5.x/geoserver-1.5.x-latest-bin.zip
Cheers
Andrea
Note also that in nightly builds we now have a more accurate code for Google Maps overlays. 4326 isn't accurate on google maps at many zoom levels. So download the latest builds and use 900913 for your overlay. Note that the builds also have an updated gs-wms.js
best regards,
Chris
Andrea Aime wrote:
Fernando Zuriaga ha scritto:
Hi, I have a problem with re-projection. My layer is in oracle table,
in ED50(EPSG:23030). When I request wms map to Geoserver, and
specify the SRS to EPSG:4326 (to represent into googlemaps), the transformation is about 80 meters from the correct location. I view the SRS info for 23030 with srsHelp.do, and the bursa wolf
parameters:
TOWGS84[-157.89, -17.16, -78.41, 2.118, 2.697, -1.434,
-1.1097046576093785]
¿Geoserver can re-project between two diferent ellipsoids?
Yes, it can.
¿This parameters are correct?, I find other parameters searching into
mailing-list-archives.
Well, these parameters come from the official EPSG database. Yet, for
some areas the EPSG database defines more than one set of TOWGS84
coefficients, and our code extracts just one of them... we should add
ways to extract alternate ones too, but for the moment we don't have
the resources to attack this problem (it seems simple, but in fact it
would require various changes to both GeoServer and GeoTools).
¿Can I modify this parameters?¿Where?
There is a way to alter the EPSG database directly, but its very
complicated.
If you want to try out with other parameters I suggest you create your
own custom projection in the
geoserver_data_dir/user_projections/epsg.properties file, using
a code of your invention (but not used by the official epsg database),
and setting different parameters. Some instructions here:
http://docs.codehaus.org/display/GEOSDOC/Custom+projection+definition+in+Geoserver+1.5.0+(onwards)
Let me know how it goes, 80 meters seems a whole lot to me (I was
expecting something around 5-10 meters). Also, today I fixed an issue
in CRS handling which may affect this behaviour... you may want to try
out this nightly build: http://geo.openplans.org/nightly/1.5.x/geoserver-1.5.x-latest-bin.zip
Cheers
Andrea
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GREAT!, I download the last nightly version, and the positions are accurate!!!. Now I can represent my bb.dd layers over GoogleMaps.
Thanks…
Regards:
F.Zuriaga
2007/8/16, Chris Holmes < cholmes@anonymised.com>:
Note also that in nightly builds we now have a more accurate code for
Google Maps overlays. 4326 isn’t accurate on google maps at many zoom
levels. So download the latest builds and use 900913 for your overlay.
Note that the builds also have an updated gs-wms.js
best regards,
Chris
Andrea Aime wrote:
Fernando Zuriaga ha scritto:
Hi, I have a problem with re-projection. My layer is in oracle table,
in ED50(EPSG:23030). When I request wms map to Geoserver, and
specify the SRS to EPSG:4326 (to represent into googlemaps), the
transformation is about 80 meters from the correct location. I view
the SRS info for 23030 with srsHelp.do, and the bursa wolf
parameters:
TOWGS84[-157.89, -17.16, -78.41, 2.118, 2.697, -1.434,
-1.1097046576093785]
¿Geoserver can re-project between two diferent ellipsoids?
Yes, it can.
¿This parameters are correct?, I find other parameters searching into
mailing-list-archives.
Well, these parameters come from the official EPSG database. Yet, for
some areas the EPSG database defines more than one set of TOWGS84
coefficients, and our code extracts just one of them… we should add
ways to extract alternate ones too, but for the moment we don’t have
the resources to attack this problem (it seems simple, but in fact it
would require various changes to both GeoServer and GeoTools).
¿Can I modify this parameters?¿Where?
There is a way to alter the EPSG database directly, but its very
complicated.
If you want to try out with other parameters I suggest you create your
own custom projection in the
geoserver_data_dir/user_projections/epsg.properties file, using
a code of your invention (but not used by the official epsg database),
and setting different parameters. Some instructions here:
http://docs.codehaus.org/display/GEOSDOC/Custom+projection+definition+in+Geoserver+1.5.0+(onwards)
Let me know how it goes, 80 meters seems a whole lot to me (I was
expecting something around 5-10 meters). Also, today I fixed an issue
in CRS handling which may affect this behaviour… you may want to try
out this nightly build:
http://geo.openplans.org/nightly/1.5.x/geoserver-1.5.x-latest-bin.zip
Cheers
Andrea
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Still grepping through log files to find problems? Stop.
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