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<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Dear Joe,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">For this case in cs2cs you have to add a +towgs84 parameter too. If you don’t want a datum transformation: +towgs84=0,0,0,0,0,0,0 on both sides.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB" style="mso-fareast-language:EN-US">Regards, Jochem<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> PROJ <proj-bounces@lists.osgeo.org>
<b>On Behalf Of </b>Joseph Boardman<br>
<b>Sent:</b> woensdag 19 januari 2022 21:25<br>
<b>To:</b> proj@lists.osgeo.org<br>
<b>Subject:</b> [PROJ] Fwd: some help with cm-level GRS80 to WGS-84 transformation?<o:p></o:p></span></p>
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<p class="MsoNormal">some help with cm-level GRS80 to WGS-84 transformation?<o:p></o:p></p>
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<p class="MsoNormal">Wed, 19 Jan 2022 11:28:24 -0700<o:p></o:p></p>
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<p class="MsoNormal" align="right" style="text-align:right"><b>From: <o:p></o:p></b></p>
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<p class="MsoNormal">Joseph Boardman <a href="mailto:boardman@aigllc.com"><boardman@aigllc.com></a><o:p></o:p></p>
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<p class="MsoNormal" align="right" style="text-align:right"><b>To: <o:p></o:p></b></p>
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<p class="MsoNormal"><a href="mailto:proj@lists.osgeo.org">proj@lists.osgeo.org</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
<p>Dear Proj Experts,<o:p></o:p></p>
<p>I'm a remote sensing geophysicist with experience in geodesy and mapping.<o:p></o:p></p>
<p>Right now I'm struggling trying to get a high-accuracy proj command to convert from GRS80 to WGS-84 at the cm level.<o:p></o:p></p>
<p>Any clues? cs2cs is not doing it.<o:p></o:p></p>
<p><span style="font-size:11.5pt;font-family:"Arial",sans-serif;color:#1D1C1D">cs2cs +proj=lonlat +ellps=WGS84 +to +proj=lonlat +ellps=GRS80 -d 8<br>
-120 40<br>
-120.00000000 40.00000000 0.00000000</span><o:p></o:p></p>
<p>Do I need to do a transformation pipeline per the 8.2.1 docs and use a Helmert transform? Any help much appreciated.<o:p></o:p></p>
<p>Best,<o:p></o:p></p>
<p>Joe<o:p></o:p></p>
<p><br>
<br>
<o:p></o:p></p>
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