[mapserver-users] MapServer 4.8.3: MapScript setProjection
Simon Greig
simon_greig at uk.ibm.com
Fri Apr 4 07:50:21 PDT 2008
Daniel,
I think I owe you an apology!
In your email last week you said:
> Sounds like you may have a layer which uses CONNECTIONTYPE WMS. This is
> a layer that is actually a connection to a remote WMS service, and one
> of the things MapServer needs to know in order to build a succesful
> GetMap request to that remote server is the SRS supported by that
server.
I had said that this was not possible.
The database team reported that they suspected that we get the projection
error for layers that have been pre-rendered into rasters. We inspected
the code and found that if the layer is pre-rendered then our custom WMS
servlet replaces the layer definition supplied by our data catalogue
database with a hardcoded raster layer.
In order to serve up the raster, the code replaces the DB loaded layer
with a new layer with a connection type of "WMS" - it supplies the URL of
our WMS server (i.e. it calls itself)
So my plan to fix this was to update the code that currently says:
FOR EACH layer
IF inputdata.projection <> epsg:27700 // It always is 27700 in our
reference data so the setProjection is never called
layer.setProjection ("init=epsg:27700")
END IF
etc etc
END FOR
Change the above to say:
FOR EACH layer
IF inputdata.projection <> epsg:27700 OR inputdata.connectionType =
WMS
layer.setProjection ("init=epsg:27700")
END IF
etc etc
END FOR
As you say, if it is mandatory for WMS connections to have a projection
then this makes sense. It means we can't get our performance savings for
raster layers but that is a constraint and we can make savings elsewhere.
Thank you for the advice.
Regards
Simon
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