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<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>I’ve seen this problem on some Spherical Mercator maps,
but generally they should line up. I notice that in Singapore, Google Satellite
and Bing street are out by a large amount that looks like a failure to apply
the WGS84 datum when calculating degrees lat lon.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>If the problem is a datum shift, it might be possible to correct
it by converting the coordinates from Spherical degrees to WGS84 degrees. I do this
in a static map generator, where the formulae I was using gave spherical degrees
instead of real WGS degrees. I converted the spherical degrees back to metres (i.e.
900913 projection), using the reverseMercator formulae from the OL
SphericalMercator source file. Then I converted the metres to proper WGS84,
using the Proj4 library. This might be kludgy, but it works. (If anyone knows a
more elegant way of doing it, I’d be grateful.)<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'> <o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>However, just one thing – you have the units defined as ‘ft’
in your map global options. I think this should be ‘m’.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><b><span style='font-family:"Verdana","sans-serif";
color:gray'>Rohan Parkes</span></b><span style='color:#1F497D'> <br>
<br>
</span><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p></o:p></span></p>
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<p class=MsoNormal><b><span lang=EN-US style='font-size:10.0pt;font-family:
"Tahoma","sans-serif"'>From:</span></b><span lang=EN-US style='font-size:10.0pt;
font-family:"Tahoma","sans-serif"'> users-bounces@openlayers.org
[mailto:users-bounces@openlayers.org] <b>On Behalf Of </b>B. Heath Robinson<br>
<b>Sent:</b> Sunday, 15 August 2010 06:38<br>
<b>To:</b> users@openlayers.org<br>
<b>Subject:</b> [OpenLayers-Users] Spherical Mercator 4326 Layers do not line
up<o:p></o:p></span></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal><span class=apple-style-span><span style='font-size:13.5pt;
font-family:"Helvetica","sans-serif"'>I am having a problem with a WMS layer
lining up on top of a Google map. It appears to be about 15mi south of
were it needs to be. I am assuming this is because of the fact that
spherical mercator ignores the fact the earth is an ellipse. Anyway, I
have included my openlayers code and my mapfile as after spending hours search
seems to be helpful.</span></span><span style='font-size:13.5pt;font-family:
"Helvetica","sans-serif"'><br>
<br>
<span class=apple-style-span>I get the same results using either a shapfile or
postgis data each with a different projection.</span><br>
<br>
<span class=apple-style-span>I am using what I believe to be the best method.
If I use "reproject:true" the map does line up, but that causes
other known problems and is deprecated. Any help would be greatly
appreciated.</span><br>
<span class=apple-style-span>---------Open Layers---------</span><br>
<span class=apple-style-span>function init(){</span><br>
<span class=apple-style-span> var
options = {</span><br>
<span class=apple-style-span> projection:
"EPSG:900913",</span><br>
<span class=apple-style-span> units:
"ft",</span><br>
<span class=apple-style-span> maxResolution:
156543.0339,</span><br>
<span class=apple-style-span> maxExtent:
new OpenLayers.Bounds(-20037508, -20037508,</span><br>
<span class=apple-style-span> 20037508,
20037508)</span><br>
<span class=apple-style-span> };</span><br>
<span class=apple-style-span> map
= new OpenLayers.Map('map', options);</span><br>
<br>
<span class=apple-style-span> var
gmap = new OpenLayers.Layer.Google(</span><br>
<span class=apple-style-span> "Google
Streets",</span><br>
<span class=apple-style-span> {'sphericalMercator':
true}</span><br>
<span class=apple-style-span> );</span><br>
<br>
<br>
</span><o:p></o:p></p>
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