<div dir="ltr">I asked about a similar issue a while back where the answer was on the fly scaling with vrt:// and *type conversion*, and constructing the geolocation array scheme with those, might be helpful : <a href="https://github.com/OSGeo/gdal/issues/8404">https://github.com/OSGeo/gdal/issues/8404</a><div><br></div><div>Cheers, Mike</div><div><br></div><div><br></div></div><br><div class="gmail_quote gmail_quote_container"><div dir="ltr" class="gmail_attr">On Sat, Sep 27, 2025 at 12:06 AM Laurențiu Nicola via gdal-dev <<a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u><div><div style="font-family:Arial">Hi,</div><div style="font-family:Arial"><br></div><div style="font-family:Arial">I have a NetCDF-style product with a separate geolocation dataset I'm trying to convert to something more easy to work with. Not sure if it matters, but the geolocation arrays are scaled. I tried to unscale them first:</div><div style="font-family:Arial"><br></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">$ cat lat.vrt</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"><VRTDataset rasterXSize="4865" rasterYSize="4090"></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <VRTRasterBand dataType="Float32" band="1" blockXSize="973" blockYSize="818"></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <NoDataValue>-2147483648</NoDataValue></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <Scale>1e-06</Scale></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SimpleSource></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SourceFilename relativeToVRT="1">NetCDF:geo_coordinates.nc:latitude</SourceFilename></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SourceBand>1</SourceBand></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SourceProperties RasterXSize="4865" RasterYSize="4090" DataType="Int32" BlockXSize="973" BlockYSize="818" /></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SrcRect xOff="0" yOff="0" xSize="4865" ySize="4090" /></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <DstRect xOff="0" yOff="0" xSize="4865" ySize="4090" /></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> </SimpleSource></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> </VRTRasterBand></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"></VRTDataset></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"></span><span style="font-family:menlo,consolas,monospace,sans-serif"><br></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">$ gdal_translate -unscale -ot Float32 lat.vrt lat.tif</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"><br></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"># same for lon.{vrt,tif}</span></div><div style="font-family:Arial"><br></div><div style="font-family:Arial">Then I made a VRT for the main dataset:</div><div style="font-family:Arial"><br></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"><VRTDataset rasterXSize="4865" rasterYSize="4090"></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <Metadata domain="GEOLOCATION"></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="X_DATASET">lon.tif</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="X_BAND">1</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="Y_DATASET">lat.tif</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="Y_BAND">1</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="PIXEL_OFFSET">0</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="LINE_OFFSET">0</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="PIXEL_STEP">1</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <MDI key="LINE_STEP">1</MDI></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> </Metadata></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <VRTRasterBand dataType="UInt16" band="1" blockXSize="1217" blockYSize="1023"></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <NoDataValue>65535</NoDataValue></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <Scale>0.01394645962864161</Scale></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SimpleSource></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SourceFilename relativeToVRT="1">Oa01_radiance.nc</SourceFilename></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SourceBand>1</SourceBand></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SourceProperties RasterXSize="4865" RasterYSize="4090" DataType="UInt16" BlockXSize="1217" BlockYSize="1023" /></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <SrcRect xOff="0" yOff="0" xSize="4865" ySize="4090" /></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> <DstRect xOff="0" yOff="0" xSize="4865" ySize="4090" /></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> </SimpleSource></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> </VRTRasterBand></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"></VRTDataset></span></div><div style="font-family:Arial"><br></div><div style="font-family:Arial">The coordinates look fine in the two TIFFs:</div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"><br></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">$ gdalinfo -stats lat.tif<br></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Driver: GTiff/GeoTIFF</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Files: lat.tif</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Size is 4865, 4090</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Image Structure Metadata:</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> INTERLEAVE=BAND</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Corner Coordinates:</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Upper Left ( 0.0, 0.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Lower Left ( 0.0, 4090.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Upper Right ( 4865.0, 0.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Lower Right ( 4865.0, 4090.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Center ( 2432.5, 2045.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Band 1 Block=4865x1 Type=Float32, ColorInterp=Gray</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> Minimum=39.552, Maximum=52.456, Mean=46.179, StdDev=3.112</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"><br></span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">$ gdalinfo -stats lon.tif</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Driver: GTiff/GeoTIFF</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Files: lon.tif</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Size is 4865, 4090</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Image Structure Metadata:</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> INTERLEAVE=BAND</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Corner Coordinates:</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Upper Left ( 0.0, 0.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Lower Left ( 0.0, 4090.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Upper Right ( 4865.0, 0.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Lower Right ( 4865.0, 4090.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Center ( 2432.5, 2045.0)</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">Band 1 Block=4865x1 Type=Float32, ColorInterp=Gray</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> Minimum=16.249, Maximum=36.250, Mean=25.532, StdDev=4.917</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> NoData Value=-2.1474836e+09</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> Metadata:</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> STATISTICS_MINIMUM=16.248615264893</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> STATISTICS_MAXIMUM=36.24991607666</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> STATISTICS_MEAN=25.532068327481</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> STATISTICS_STDDEV=4.9167101776381</span></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif"> STATISTICS_VALID_PERCENT=100</span></div><div style="font-family:Arial"><br></div><div style="font-family:Arial">However, this fails with "Warning 1: Too many points (529 out of 529) failed to transform, unable to compute output bounds.":</div><div style="font-family:Arial"><br></div><div style="font-family:Arial"><span style="font-family:menlo,consolas,monospace,sans-serif">$ gdalwarp -geoloc -t_srs EPSG:4326 Oa01.vrt Oa01.tif</span></div><div style="font-family:Arial"><br></div><div style="font-family:Arial">The files are available at <a href="https://nas.dend.ro/browse/datasets/Oa01.zip" target="_blank">https://nas.dend.ro/browse/datasets/Oa01.zip</a>, if anyone can to take a look.</div><div style="font-family:Arial"><br></div><div style="font-family:Arial">Thanks,</div><div style="font-family:Arial">Laurentiu<br></div></div>_______________________________________________<br>
gdal-dev mailing list<br>
<a href="mailto:gdal-dev@lists.osgeo.org" target="_blank">gdal-dev@lists.osgeo.org</a><br>
<a href="https://lists.osgeo.org/mailman/listinfo/gdal-dev" rel="noreferrer" target="_blank">https://lists.osgeo.org/mailman/listinfo/gdal-dev</a><br>
</blockquote></div><div><br clear="all"></div><div><br></div><span class="gmail_signature_prefix">-- </span><br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div dir="ltr" style="color:rgb(34,34,34)"><div dir="ltr">Michael Sumner</div><div dir="ltr">Ordinary Member, Streets People Love Hobart Association<br>Research Software Engineer<br>Australian Antarctic Division<br>Hobart, Australia</div><div dir="ltr">0438489030<br>e-mail: <a href="mailto:mdsumner@gmail.com" style="color:rgb(17,85,204)" target="_blank">mdsumner@gmail.com</a></div></div></div></div>