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<p>Hi Nicolas and André,</p>
<p>To be honest I don't know much how you setup QGIS properly to use the grid shift files. I just wanted to say that the support is there, but probably needs some improvements or better explanation/documentation.</p>
<p>For my own country's date shifts, "it just works", probably because the configuration is already built into QGIS because the grid-shift support was developed for a Swiss customer. The only thing I had to do is to download the grid shift file and place it in share\proj.</p>
<p>It may well be that to make it easier to use grid shift files for the average user, there should be improvements in the way the grid shift files are organized and used in QGIS. Having to create a custom projection is not very user friendly.</p>
<p>Maybe it would also be more user friendly, if QGIS would already deliver the grid shift files for most countries. But that would bloat QGIS quite a bit. The grid shift file for Switzerland (one of the smallest countries in the world) is already 3 MB. Maybe a grid shift file manager and repository would help for downloading, installing and deleting the files and for setting it up properly for easy usage.</p>
<p>So if you have proposals how to improve, please bring them up.</p>
<p>Andreas</p>
<p>On 2016-04-01 08:48, Andre Joost wrote:</p>
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<div class="pre" style="margin: 0; padding: 0; font-family: monospace"><span style="white-space: nowrap;">Am 01.04.2016 um 08:12 schrieb Andre Joost:</span>
<blockquote type="cite" style="padding: 0 0.4em; border-left: #1010ff 2px solid; margin: 0"><span style="white-space: nowrap;">Am 31.03.2016 um 16:55 schrieb Nicolas Cadieux:</span>
<blockquote type="cite" style="padding: 0 0.4em; border-left: #1010ff 2px solid; margin: 0"><span style="white-space: nowrap;">Hi Andreas,</span><br /><span style="white-space: nowrap;">That is very interesting. I would like to know more about these grids</span><br /><span style="white-space: nowrap;">and how QGIS deals with it. Do you have any additional links to</span><br /><span style="white-space: nowrap;">share?</span><br /><span style="white-space: nowrap;">All I can see is that the proj4 parameters for many of the CRS in</span><br /><span style="white-space: nowrap;">North America are identical and lead to no actual changes in the</span><br /><span style="white-space: nowrap;">coordinate unless you are going from nad27 to nad 83 or Wgs84 which is</span><br /><span style="white-space: nowrap;">more drastic.</span><br /><span style="white-space: nowrap;">That is why I use the nrcan tool that can do transformation based</span><br /><span style="white-space: nowrap;">on ITRF and WGS84 CRS.</span><br /><span style="white-space: nowrap;">I would be nice to do that strait in QGIS. I will look into your</span><br /><span style="white-space: nowrap;">method and report back.</span></blockquote>
<br /><span style="white-space: nowrap;">QGIS already uses a grid shift file internally for the conversion from</span><br /><span style="white-space: nowrap;">NAD27 to WGS84. But there is not yet any grid shift file that reflects</span><br /><span style="white-space: nowrap;">newer tectonic moves, like NAD83(CSRS98) would need.</span><br /><br /></blockquote>
<br /><span style="white-space: nowrap;">Update: You might find some grid file resources in the following document:</span><br /><br /><span style="white-space: nowrap;"><<a href="http://downloads2.esri.com/support/TechArticles/Grid-based_Transformation_Methods_for_Canada3.pdf">http://downloads2.esri.com/support/TechArticles/Grid-based_Transformation_Methods_for_Canada3.pdf</a>></span><br /><br /><span style="white-space: nowrap;">HTH,</span><br /><span style="white-space: nowrap;">André Joost</span><br /><br /><br /> _______________________________________________<br /><span style="white-space: nowrap;">Qgis-user mailing list</span><br /><span style="white-space: nowrap;"><a href="mailto:Qgis-user@lists.osgeo.org">Qgis-user@lists.osgeo.org</a></span><br /><span style="white-space: nowrap;">List info: <a href="http://lists.osgeo.org/mailman/listinfo/qgis-user">http://lists.osgeo.org/mailman/listinfo/qgis-user</a></span><br /><span style="white-space: nowrap;">Unsubscribe: <a href="http://lists.osgeo.org/mailman/listinfo/qgis-user">http://lists.osgeo.org/mailman/listinfo/qgis-user</a></span></div>
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