The formula for "Google Mercator" Y coordinate is:<br><br>6378137 * LN ( TAN ( PI / 4.0 + LAT / 2.0 ) )<br><br>For LAT=52.4827802220782 you get 6887893.49, which is what you are obtaining with proj.<br>The other value is some 30 km smaller. May be it was calculated with the actual Mercator projection of the ellipsoid.<br>
<br>Regards<br><br>José Gonçalves <br><br><br><br><div class="gmail_quote">2011/8/4 zagot <span dir="ltr"><<a href="mailto:maurelio@live.it">maurelio@live.it</a>></span><br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Hi to All,<br>
this is an oldie, but i cannot seem to find a solution.<br>
When i want to do a transform on a wgs84 to google/bing the y coordinate<br>
shifts.<br>
<br>
I have read this variuos post and this official note:<br>
<a href="http://trac.osgeo.org/proj/wiki/FAQ#ChangingEllipsoidWhycantIconvertfromWGS84toGoogleEarthVirtualGlobeMercator" target="_blank">http://trac.osgeo.org/proj/wiki/FAQ#ChangingEllipsoidWhycantIconvertfromWGS84toGoogleEarthVirtualGlobeMercator</a><br>
<br>
...so I tried adding +nadgrids=@null like i read, but with this example:<br>
<br>
from ..."+proj=latlong +datum=WGS84";<br>
<br>
to... "+proj=merc +a=6378137 +b=6378137 +lat_t1=0.0 +lon_0=0.0 +x_0=0.0<br>
+y_0=0 +k=1.0 +units=m +nadgrids=@null +no_defs"<br>
<br>
i have this result -626172.1357121646, 6887893.4928337997<br>
<br>
in the result y differ from correct value:6853955.508199729 (with Proj.NET<br>
the result is correct)<br>
<br>
..seems adding +nadgrids=@null have no effect<br>
<br>
what's I wrong?<br>
<br>
thanks in advance<br>
<br>
sorry for my english<br>
thanks<br>
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