WMS and SRS

[Daniel Goetz]

Hi coummunity,

I built up a littel WMS-server with umn-mapserver (local installation; ms4w 2.1). The "original" projection of the single Layers is alway epsg:31468 (these are cartesian Gauß-Krüger-coordiantes). So I set the PORJECTION-object of each LAYER and in the MAP-object to "init=epsg:31468". In the METADATA of the MAP-object as well as in the single LAYER-objects I defined "wms_srs" as "EPSG:31468" as well. For testing purpose I did some WMS-GetMap-Requests with "SRS=EPSG:31468" and everything went fine.

But now I want to make my WMS-service more interchangeable, so I want to define some more SRSs in that the WMS should be able to be displayed. I want to make it possible to "transform" (don't know the exact word in english) the WMS from its original Projection to another SRS (e.g. WGS 84; EPSG:4326). In my opinion this should be possible by adding another epsg-code to the METADATA. So my METADATA (both in the MAP and in the LAYERs-objects) look like this: "wms_srs" "EPSG:31468 EPSG:4326".

But now every time I change the SRS block in my WMS-GetMap-request from "SRS=EPSG:31468" to "SRS=EPSG:4326" mapserver returns a blank image. I even tried to set the BBOX to latlon-coordinates when using "SRS=EPSG:4326" but even this failed. I also testes other SRSs (both geographic ones and real projections) but with no success.

Could anybody please give me some help or hints what to do and what went wrong and why did this happen? I would be very glad and thankful. Thank you so much.


regards


Daniel


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