Marc,<br><br>You don't need to rebuild proj.4; you are already using it. Since you were able to use ogr2ogr to do the transformation, it works.<br><br>What you need to do is find out if the arguments you are passing to the transformation builder are good. Especially 'MapSRS'. If it doesn't show any problem, plug some debug messages in the OSR code in ogrct.cpp and rebuild gdal.<br>
<br><div class="gmail_quote">On Wed, Oct 19, 2011 at 12:46 PM, <span dir="ltr"><<a href="mailto:dev4cx4m9z@snkmail.com">dev4cx4m9z@snkmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
<div link="blue" vlink="purple" lang="EN-AU"><div><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);">Thanks for all the suggestions – they have given me many possibilities to eliminate, but I still haven’t really got an answer to the original question.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">Am I required to have proj.dll built with support for the datums/projections I want to use, or is it sufficient to set GDAL_DATA such that gcs.csv and pcs.csv are visible? I’m working in <a href="http://VB.NET" target="_blank">VB.NET</a>, and I’m not confident I can rebuild PROJ with the required datums, so I wish to avoid if possible. I’d even be prepared to use SetGeogCS explicitly as I only use a few datums. If I use SetGeogCS, I can’t see what purpose proj.dll serves.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">I have set GDAL_DATA to the correct folder.<u></u><u></u></span></p>
<p class="MsoNormal"><span style="font-size: 11pt; color: rgb(31, 73, 125);" lang="EN-US">I have checked that the datum numbers I use are in the gcs.csv file.<u></u><u></u></span></p><div><div></div><div class="h5"><p class="MsoNormal">
<span style="font-size: 11pt; font-family: "Courier New"; color: rgb(31, 73, 125);" lang="EN-US"><u></u> <u></u></span></p><div><div style="border-width: 1pt medium medium; border-style: solid none none; border-color: rgb(181, 196, 223) -moz-use-text-color -moz-use-text-color; padding: 3pt 0cm 0cm;">
<p class="MsoNormal"><b><span style="font-size: 10pt;" lang="EN-US">From:</span></b><span style="font-size: 10pt;" lang="EN-US"> <a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a> [mailto:<a href="mailto:gdal-dev-bounces@lists.osgeo.org" target="_blank">gdal-dev-bounces@lists.osgeo.org</a>] <b>On Behalf Of </b><a href="mailto:dev4cx4m9z@snkmail.com" target="_blank">dev4cx4m9z@snkmail.com</a><br>
<b>Sent:</b> Tuesday, October 18, 2011 4:12 AM<br><b>To:</b> <a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br><b>Subject:</b> RE: [gdal-dev] Confused about datum transformations<u></u><u></u></span></p>
</div></div><p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p><p class="MsoNormal" style="">I’m not sure the code will help too much, but here are the relevant code fragments. I’m using a hand crafted VB.net wrapper which explains some of the syntax<u></u><u></u></p>
<p class="MsoNormal" style=""><u></u> <u></u></p><p class="MsoNormal" style="">Private WGS84SRS As New OGRSpatialReference ' Coordinate system in WGS84<u></u><u></u></p><p class="MsoNormal" style="">Private MapSRS As OGRSpatialReference ' Coordinate system of map<u></u><u></u></p>
<p class="MsoNormal" style="">Private ctWGS84toMap As OGRCoordinateTransformation ' Coordinate transform from WGS84 to map<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal" style="">With WGS84SRS<u></u><u></u></p>
<p class="MsoNormal" style=""> GDALError = .SetProjCS("WGS84 Datum")<u></u><u></u></p><p class="MsoNormal" style=""> Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())<u></u><u></u></p><p class="MsoNormal" style="">
GDALError = .SetWellKnownGeogCS("WGS84") ' Define WGS84 coordinate system<u></u><u></u></p><p class="MsoNormal" style=""> Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())<u></u><u></u></p>
<p class="MsoNormal" style="">End With<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal" style="">With MapSRS<u></u><u></u></p><p class="MsoNormal" style=""> GDALError = .SetProjCS("Map coordinate system")<u></u><u></u></p>
<p class="MsoNormal" style=""> Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())<u></u><u></u></p><p class="MsoNormal" style=""> GDALError = .ImportFromEPSG(3577)<u></u><u></u></p><p class="MsoNormal" style="">
Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())<u></u><u></u></p><p class="MsoNormal" style="">End With<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal" style="">ctWGS84toMap = GDAL.CreateCoordinateTransformation(WGS84SRS, MapSRS) ' Create a coordinate transformation - WGS84 to map<u></u><u></u></p>
<p class="MsoNormal" style="">Debug.Assert(ctWGS84toMap IsNot Nothing, GetLastErrorMsg())<u></u><u></u></p><p class="MsoNormal"><u></u> <u></u></p><p class="MsoNormal" style="margin-bottom: 12pt;">Marc,<br><br>Can you provide the code leading to the error?<u></u><u></u></p>
<div><p class="MsoNormal">On Tue, Oct 18, 2011 at 1:21 PM, Marc Hillman <<a href="mailto:dev4cx4m9z@snkmail.com" target="_blank">dev4cx4m9z@snkmail.com</a>> wrote:<u></u><u></u></p><div><div><p class="MsoNormal">I have a GIS database, and all data is stored in WGS84 datum. I have developed an application using GDAL, and I now need to translate my WGS84 coordinates to several different datums, depending what map is loaded. I seem to be going around in circles, and need a nudge in the right direction. I am defining an OGRSpatialReference for each datum (WGS84 and current map) and then attempting to create an OGRCoordinateTransformation for the transformation.. This last step fails with a PROJ.4 error (“No PROJ.4 translation for destination SRS, coordinate transformation initialization failed”<u></u><u></u></p>
<p class="MsoNormal"> <u></u><u></u></p><p class="MsoNormal">My question is - Do I need PROJ.4 to do the translation? Can I not just use ImportFromWKT to define my OGRSpatialReference? If so, is there a nice canned list of all the WKT somewhere? I’m keen to avoid PROJ.4 if possible as I’m not sure I can build it.<u></u><u></u></p>
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