[OpenLayers-Users] Google/Yahoo map projection WMS overlay question

[bradleyspencer]

Andrew,

As I understand it if you specify the base map in sphericalMercator and wish
to see WMS layers overlayed at both large and small scales correctly, your
WMS server must have the capability to serve up data in EPSG:900913. So you
need to look at your GetCapabilities document of the WMS and determine if it
supports this projection. If it does not, then I would suggest you do not
use sphericalMercator at all and just overlay in EPSG:4326 and remember that
the alignment drifts off when at small scales. Alternatively, (Long shot)
look for a cascading WMS server that does support this projection and ask
the custodians to register your WMS in their service so you can cascade
through their WMS letting it do the retransformation for you.

Hope this helps
.

Brad Spencer


-----Original Message-----
From: users-bounces at openlayers.org [mailto:users-bounces at openlayers.org]On
Behalf Of Andrew Murdoch
Sent: Monday, 24 December 2007 3:58 AM
To: users at openlayers.org
Subject: [OpenLayers-Users] Google/Yahoo map projection WMS overlay question

Are there any good examples of using Google or Yahoo background data (in
their native Spherical Mercator projection) with WMS services in WGS84
(EPSG: 4326)?  I looked through the examples directory, but couldn't find
anything that seemed to work.  I don't seem to be able to get my WMS layers
(from GeoServer) to show up at all though the commercial background layers
do show up.  I thought that if the map were defined in Spherical Mercator
then the WMS layers (in EPSG 4326) would automatically be requested in the
Google projection.

Thanks for your help!
Andrew Murdoch

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