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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Hi,<o:p></o:p></span></p>
<p class="MsoNormal"><span 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 did not have a close look into your ground control points but perhaps they are not very well distributed and therefore the default warping algorithm eats one corner of the image. Have
a try with thin plate splin (-tps) instead. There may be some bug, it does not feel right that some source data are lost with default algorithm.<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>
<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><span lang="EN-US">Lähettäjä:</span></b><span lang="EN-US"> Hays Barrett <hays.barrett@gmail.com>
<br>
<b>Lähetetty:</b> tiistai 30. maaliskuuta 2021 19.32<br>
<b>Vastaanottaja:</b> Rahkonen Jukka (MML) <jukka.rahkonen@maanmittauslaitos.fi><br>
<b>Kopio:</b> gdal-dev@lists.osgeo.org<br>
<b>Aihe:</b> Re: [gdal-dev] Adding gcps to a raster using gdal_translate can result in data loss.<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">I put together a page that better explains the issue and used one of the actual images from our project.<o:p></o:p></p>
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<p class="MsoNormal"><a href="https://haysbarrett.com/gdal_translate/">https://haysbarrett.com/gdal_translate/</a><o:p></o:p></p>
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<p class="MsoNormal">Thanks for looking into this for me.<o:p></o:p></p>
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<p class="MsoNormal">-Hays<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Fri, Mar 26, 2021 at 2:59 PM jratike80 <<a href="mailto:jukka.rahkonen@maanmittauslaitos.fi">jukka.rahkonen@maanmittauslaitos.fi</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal">Hi,<br>
<br>
Please give an exact example. Preferably with a raster that can be created<br>
from command line with gdal_create followed by other required commands. Or<br>
alternatively Python code that re-produces the issue.<br>
<br>
-Jukka Rahkonen-<br>
<br>
<br>
<br>
Hays Barrett wrote<br>
> If the gcps stretch the image beyond the dimensions of the original raster<br>
> it appears to clip the data that sits outside of the original raster<br>
> dimensions rather than increase the raster dimensions to fit the stretched<br>
> data . <br>
> Is this the expected behavior? <br>
> If so is there a way to increase the dimensions of a raster so there is no<br>
> data loss? <br>
> Thanks, <br>
> -Hays <br>
> <br>
> _______________________________________________<br>
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<br>
<br>
<br>
<br>
<br>
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