[mapserver-users] Mapserver WMS Reprojection

[Rahkonen Jukka]

Hi,

The Web Mercator projection is in meters too and your map will be switched off also with EPSG:27700 if you zoom far enough. Due to differences in projection settings the turn on/off may not happen in exactly same visible scale.  Play with the MAXSCALEDENOM value and perhaps you will find something that works for both of your projections.  If not, you can always copy the whole LAYER with a different name and edit the new layer to be optimal for OpenLayers.

-Jukka Rahkonen-

Donald Kerr wrote:
> 
> Jukka,
> 
> Got it! DEBUG 5 spotted the error:
> 
> "Skipping layer (CME) because LAYER.MAXSCALE is too small for this MAP
> scale"
> 
> I have the following:
> 
> MINSCALEDENOM 1
> MAXSCALEDENOM 36000
> SYMBOLSCALEDENOM 24000
> 
> If I comment them out then all is well and the required image is created and
> served.
> 
> Now, the issue would appear to be that these figures are relevant to 27700
> and work with that in metres but do not work with 900913 which I assume is
> in degrees. The request SRS for a WMS is controlled by Openlayers so this is
> fixed as 90013 and I do have the map set for metres. The BBOX must be sent
> from Openlayers in degrees so I am think that this is where the problem is.
> Maybe I cannot use MAXSCALEDENOM in these circumstances where I need
> to serve in two projections.
> 
> Many thanks.
> 
> Regards,
> 
> Donald
> 
> 
> 
> -----Original Message-----
> From: Rahkonen Jukka [mailto:jukka.rahkonen at mmmtike.fi]
> Sent: 20 May 2013 05:53
> To: Donald Kerr; mapserver-users at lists.osgeo.org
> Subject: Re: [mapserver-users] Mapserver WMS Reprojection
> 
> Hi,
> 
> I do not see obvious error and the 900913 BBOX hit UK somewhere in
> Scotland so I guess that you have data there. I was thinking that the fake
> 900913 code is perhaps not included in the EPSG file and you should use
> EPSG:3785 instead but that case that would propably lead to some error
> message. Have still a try with 3785, and add DEBUG 5 into your layer setting
> and see what you get into your MS_ERRORFILE.
> 
> -Jukka Rahkonen-
> 
> 
> Donald Kerr wrote:
> 
> > Slight mistake below; the projection definition in the layer is as
> > follows with "epsg" in lowercase as I am led to believe that it should
> > be
> so:
> > "init=epsg:27700"
> 
> -----Original Message-----
> From: mapserver-users-bounces at lists.osgeo.org
> [mailto:mapserver-users-bounces at lists.osgeo.org] On Behalf Of Donald Kerr
> Sent: 19 May 2013 20:36
> To: mapserver-users at lists.osgeo.org
> Subject: [mapserver-users] Mapserver WMS Reprojection
> 
> > Hi List,
> 
> > I am trying to reproject a WMS request from 27700 (UK Ordnance Survey)
> > to
> 900913 (OSM OpenStreetMap) without success. There no issue with the map
> file map or layer definitions in terms of serving up the WMS in 27700 but
> reprojection seems to fail. There appears to be very little online and I cannot
> find a solution; hence this request for help or advice.
> 
> > Relevant parts of map file (some parts removed):
> 
> >PROJECTION
>     "init=epsg:27700"
> END
> 
> WEB
>     METADATA
>         "wms_title" "My WMS"
>         "wms_onlineresource"  "http://localhost/mapserver/mapserv.asp?"
>         "wms_srs" "EPSG:27700  EPSG:900913"
>         "wms_enable_request" "*"
>         "wms_abstract" "My WMS"
>         "wms_extent" "0 0 670000 1230000"
>         "wms_feature_info_mime_type" "text/plain"
>         "wms_feature_info_mime_type" "text/html"
>         "wms_feature_info_mime_type" "application/vnd.ogc.gml" #
> &info_format=application/vnd.ogc.gml
> ..
> 
> Layer:
> 
> METADATA
>     "wms_title" "CME"
>     "wms_extent" "0 0 670000 1230000"
> #    "wms_srs" "EPSG:27700 EPSG:900913"
>     "wms_include_items" "all" # No spaces
>     "gml_include_items" "all" # No spaces
>     "gml_featureid" "ID"
> END
> 
> PROJECTION
>     "init=EPSG:27700"
> END # PROJECTION
> 
> > Openlayers request:
> 
> > http://maps1/cgi-
> bin/mapserv.exe?MAP=D:\MyMapFile.map&LAYERS=CME&TRANS
> > PARENT
> =TRUE&FORMAT=png&SERVICE=WMS&VERSION=1.1.1&REQUEST=GetMap
> &STYLES=&SRS=EPSG%3
> A900913&BBOX=-484682.60504583,7512726.3043776,-
> 415889.27960147,7547122.96709
> 97&WIDTH=900&HEIGHT=450
> 
> > The result is a transparent image with no data showing. :( The same
> > map file
> works correctly and serves an image if used with Openlayers and a map on
> EPSG 27700 so it's pointing at the reprojection of the BBOX maybe.
> 
> > What am I doing wrong? Any help greatly appreciated.
> 
> > Many thanks.
> 
> > Regards,
> 
> Donald
> 
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