Thanks Jean-Claude,<br><br>I was using EPSG:900913 for the OSM tiles and Googled about it looking for the +towgs84 parameter but couldn't find anything.<br>I did find several posts about EPSG:3785 being the same as EPSG:900913 and that one does have the +towgs84 parameter.<br>
Should I use that proj4 string instead?<br>+proj=merc +lon_0=0 +k=1 +x_0=0 +y_0=0 +a=6378137 +b=6378137 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs <br><br>And how about the custom projection? Do you have any idea how to create a proj4 style string from that?<br>
<br>Thanks,<br>Paul<br><br><br><div class="gmail_quote">2010/7/14 Jean-Claude REPETTO <span dir="ltr"><<a href="mailto:jrepetto@free.fr">jrepetto@free.fr</a>></span><br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
Hi,<div class="im"><br>
<br>
On 07/14/10 11:54, Paul Meems wrote:<br>
<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<br>
I'm using this proj4 string for the OSM tiles:<br>
+proj=merc +lon_0=0 +lat_ts=0 +x_0=0 +y_0=0 +a=6378137 +b=6378137<br>
+units=m +no_defs<br>
<br>
</blockquote>
<br></div>
This one is not correct if you want to do a datum transformation : the +towgs84 parameter is missing.<br>
<br>
Jean-Claude<br>
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</blockquote></div><br>