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<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">I tried to go from a Natural Earth world map in EPSG:4326 into Mollweide this way:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">gdalwarp -t_srs "+proj=moll +lon_0=0 +datum=WGS84" HYP_50M_SR_W.tif molltest.tif<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">The warped image has corner coordinates:<br>
Corner Coordinates:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Upper Left (-18040095.696, 9020047.848)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Lower Left (-18040095.696,-9020044.507)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Upper Right (18040095.696, 9020047.848)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Lower Right (18040095.696,-9020044.507)<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Warping back to EPSG:4326 looks rather good with some small artifacts at the corners. Thus, the corner coordinates for -ullr should be close to these values. However, your original is
wider that the Earth. Clip the margins away so that the globe sits tightly in the box and try with -ullr -18040095.696 9020047.848 18040095.696 -9020044.507.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">-Jukka Rahkonen-<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>Lähettäjä:</b> Rahkonen Jukka <br>
<b>Lähetetty:</b> maanantai 28. lokakuuta 2024 23.21<br>
<b>Vastaanottaja:</b> Rick Kohrs <rick.kohrs@ssec.wisc.edu>; gdal-dev@lists.osgeo.org<br>
<b>Aihe:</b> Re: Mollweide to plate_carree<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">I do not really know how to georeference such Mollweide image, but certainly it is not with -a_ullr -180 90 180 -90. The upper-left and lower-right corners mean the corners of the raster,
and both those corners are on the black area outside the Earth. Look at the earth-egg and you can imagine that the coordinates -180 90 180 -90 are at the poles and they are not at all at the corners of the image. But even if you make the poles as ground control
points and save them into GeoTIFF with correct pixel coordinates (something like 630x 58y and 630x 660y), you will only have two GCPs on a vertical line and that is not enough for warping. I apologize that I can’t tell how to do it right and where to get enough
usable GCPs.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US">You wrote “The results are still in a mollweide projection” but that is not true. You can use gdalinfo and see that the result is in EPSG:4326, but because of using -a_ullr -180 90 180
-90 in the first step, there is no need to move any pixel.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">-Jukka Rahkonen-<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b>Lähettäjä:</b> gdal-dev <<a href="mailto:gdal-dev-bounces@lists.osgeo.org">gdal-dev-bounces@lists.osgeo.org</a>>
<b>Puolesta </b>Rick Kohrs via gdal-dev<br>
<b>Lähetetty:</b> maanantai 28. lokakuuta 2024 22.28<br>
<b>Vastaanottaja:</b> <a href="mailto:gdal-dev@lists.osgeo.org">gdal-dev@lists.osgeo.org</a><br>
<b>Aihe:</b> [gdal-dev] Mollweide to plate_carree<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">I have full earth mollweide projected images:<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><a href="https://www.ssec.wisc.edu/~rickk/wvsst/latest.jpg"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif">https://www.ssec.wisc.edu/~rickk/wvsst/latest.jpg</span></a><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">and need to reproject the image into plate_carree<br>
<br>
I have the following script:<br>
gdal_translate -of GTiff -a_srs "+proj=moll +lon_0=0 +datum=WGS84" -a_ullr -180 90 180 -90 global-wvsst_24291_1800.jpg intermediate_mollweide_georef.tif<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">gdal_edit.py -tr 0.1 -0.1 intermediate_mollweide_georef.tif<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">gdalinfo intermediate_mollweide_georef.tif<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">gdalwarp -t_srs "EPSG:4326" -r bilinear intermediate_mollweide_georef.tif final_output_plate_carree.tif<o:p></o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">gdalinfo final_output_plate_carree.tif<br>
<br>
The results are still in a mollweide projection. </span><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Any assistance would be greatly appreciated.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Rick<o:p></o:p></span></p>
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