How to Fix Ratty Line Rendering in WMS? - Redux

[Daniel Morissette]

Bill Thoen wrote:
> I've now posted some images showing the problem at 
> http://www.gisnet.com/wms_examples/.
> 
> To summarize the problem, I've set up a MapServer WMS Server that's got 
> road data in native MapInfo format with a coordinate system based on 
> Lat/Long (EPSG:4269). When I display it in a MapServer client map using 
> the same projection EPSG:4269, the line work looks nice and clean. 
> However, if I try to use a different projection in my client like 
> EPSG:2163 (Lambert), the lines are pretty shabby looking.
> 

Did you list EPSG:2163 in the wms_srs metadata of the CONNECTIONTYPE WMS 
layer in you client mapfile?

The "wms_srs" metadata in a client WMS connection layer definition is 
used to list all the projections (SRS) supported by the remote server. 
It's a space-separated list, e.g.

LAYER
   ...
   METADATA
     "wms_srs" "EPSGL4326 EPSG:4269 EPSG:2163"
     ...
   END
   ...
END

If the requested SRS is not found in this list then MapServer concludes 
that the remote server doesn't support that projection and then it uses 
the layer's default SRS for its GetMap call to the remote server and 
then reprojects the resulting image on the fly.

This is probably what's happening here and explains the shabby looking 
lines.

Daniel
-- 
Daniel Morissette
http://www.mapgears.com/