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<p class="MsoNormal"><a name="x__MailAutoSig"><span style="font-family:"Arial",sans-serif">I am currently looking at upgrading from GDAL 2.x to GDAL 3.x. Most of my software tests pass, but I have a few failing because a transform from WGS84 to WGS84 is flipping
the axes on transformed geometries. <o:p></o:p></span></a></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">I have a recollection of reading about GDAL 3 (or PROJ 6) resulting in axis swapping in some cases, but can’t find the discussion/Github issue again.<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">The two SRS objects appear identical, and seem to report the same axis order, but a point at (1, 0) gets transformed to (0, 1) – Python code below:<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> from_proj = ds.GetLayer().GetSpatialRef()<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> to_proj = osr.SpatialReference()<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> to_proj.ImportFromEPSG(4326)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> to_proj.GetAxisName(None, 0)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">'Geodetic latitude'<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> to_proj.GetAxisName(None, 1)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">'Geodetic longitude'<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> from_proj.GetAxisName(None, 0)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">'Geodetic latitude'<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> from_proj.GetAxisName(None, 1)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">'Geodetic longitude'<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> xform = osr.CoordinateTransformation(from_proj, to_proj)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> xform.TransformPoint(1.0, 0.0)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">(0.0, 1.0, 0.0)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">If I follow from_proj back to its origin, it is also imported by importing from an EPSG code, which is again 4326:<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> projection = osr.SpatialReference()<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> projection.ImportFromEPSG(epsg)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> temp_ds = gdal.GetDriverByName('Memory').Create('', 0, 0, 0)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> layer = temp_ds.CreateLayer(name, projection, geom_type=geom_type)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">The two SRS objects appear identical when exported to WKT:<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> from_proj.ExportToWkt()<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">'GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AXIS["Latitude",NORTH],AXIS["Longitude",EAST],AUTHORITY["EPSG","4326"]]'<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> to_proj.ExportToWkt()<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">'GEOGCS["WGS 84",DATUM["WGS_1984",SPHEROID["WGS 84",6378137,298.257223563,AUTHORITY["EPSG","7030"]],AUTHORITY["EPSG","6326"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AXIS["Latitude",NORTH],AXIS["Longitude",EAST],AUTHORITY["EPSG","4326"]]'<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">And if I re-import the SRSes from those WKT strings, the transform starts to behave:<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> from_proj_reimported = osr.SpatialReference(); from_proj_reimported.ImportFromWkt(from_proj.ExportToWkt())<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> to_proj_reimported = osr.SpatialReference(); to_proj_reimported.ImportFromWkt(to_proj.ExportToWkt())<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> new_xform = osr.CoordinateTransformation(from_proj_reimported, to_proj_reimported)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">>>> new_xform.TransformPoint(1.0, 0.0)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">(1.0, 0.0, 0.0)<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif">How are these two SRS objects ending up with flipped axes, how can I actually tell that the axes are flipped, and what do I need to do to un-flip them
(short of exporting and reimporting every time I use them)?<o:p></o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><b><span style="font-family:"Arial",sans-serif;color:black;mso-fareast-language:EN-GB"><o:p> </o:p></span></b></span></p>
<p class="MsoNormal"><span style="mso-bookmark:x__MailAutoSig"><b><span style="font-family:"Arial",sans-serif;color:black;mso-fareast-language:EN-GB">Dr. Daniel Evans</span></b></span><span style="mso-bookmark:x__MailAutoSig"></span><span style="font-family:"Arial",sans-serif;color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:#F6A124;mso-fareast-language:EN-GB">Software Developer</span><span style="font-family:"Arial",sans-serif;color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:#F6A124;mso-fareast-language:EN-GB"> </span><span style="font-family:"Arial",sans-serif;color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black;mso-fareast-language:EN-GB"><a href="sip:daniel.evans@jbarisk.com"><b><span style="color:#F6A124">Skype</span></b></a><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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