<br><div class="gmail_quote"><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>
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I'm not too familiar with proj definitions but it seems that this:<br>
<br>
+proj=tmerc +lon_0=-81 +k=0.9996+x_0=500000 +datum=WGS84<br>
<br>
is really just an alias for:<br>
<br>
+proj=utm +zone=17 +datum=WGS84</blockquote><div><br>UTM use the same method than transverse mercator. UTM is a nice way to talk about transverse mercator. For example geotrans when call to UTM internally prepare the parameters of the equivalent transverse mercator. <br>
In quamtum gis you have many definitions of projections in the proj format by countries:<br><a href="http://www.qgis.org/">http://www.qgis.org/</a><br><br>In proj library you have also many definitions in that format but in a unique text file.<br>
<a href="http://download.osgeo.org/proj/proj446_win32_bin.zip">http://download.osgeo.org/proj/proj446_win32_bin.zip</a><br><br>regards.<br><br><br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
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It probably doesn't matter but the latter seems more readable. On the other hand most users should know -81 = zone 17.<br>
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Thanks again<div><div></div><div class="Wj3C7c"><br>
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