<div dir="auto"><div>There are only very specific cases where it would be valid to directly copy overview tiles, namely if both image sizes are an exact power of 2. I'll let Even contradict me if I'm wrong, but I highly doubt that what you are trying to do is possible.</div><div dir="auto">regards,</div><div dir="auto">Thomas<br><br><div class="gmail_quote" dir="auto"><div dir="ltr" class="gmail_attr">Le jeu. 6 oct. 2022, 05:58, Ian Reese <<a href="mailto:xycarto@gmail.com">xycarto@gmail.com</a>> a écrit :<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-size:small">Hi GDAL,</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">Let's say I have two GTiff files in COG format:</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">f1.tif</div><div class="gmail_default" style="font-size:small">f2.tif</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">f1.tif and f2.tif are created like so:</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small"><table><tbody><tr><td id="m_-3397547538372092727gmail-LC15">gdal_translate input.tif <span>f1.tif</span> \</td></tr><tr></tr></tbody></table><table><tbody><tr><td id="m_-3397547538372092727gmail-LC16">-of COG \</td>
</tr>
<tr>
</tr></tbody></table><table><tbody><tr><td id="m_-3397547538372092727gmail-LC17"> -co BLOCKSIZE=256 \</td>
</tr>
<tr>
</tr></tbody></table> -co COMPRESS=JPEG \</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">I can easily create a vrt of these two COGs and get the expected behaviour where the VRT honours the overviews of the f1 and f2 COGs.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">gdalbuildvrt cog.vrt f1.tif f2.tif</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">This is my question, is it possible to create a COG Tif from this VRT that copies over the overviews from each COG in the VRT?</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">For example something like:<br><br></div><div class="gmail_default" style="font-size:small">gdal_translate cog.vrt cog.tif -of COG -co OVERVIEWS=FORCE_USE_EXISTING</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">I suspect this may not be possible. My guess is that translate is confused by which overviews to use when creating the single cog.tif? Or that when I created f1.tif and f2.tif I missed a setting?</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">I have tried many combinations to get this to work, but I think it might be time to ask the experts. Any insight to this would be greatly appreciated.</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">Cheer,</div><div class="gmail_default" style="font-size:small"><br></div><div class="gmail_default" style="font-size:small">Ianto<br clear="all"></div><div class="gmail_default" style="font-size:small"><div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:"Droid Sans Mono","monospace",monospace;font-weight:normal;font-size:14px;line-height:19px;white-space:pre-wrap"><div><span style="color:rgb(212,212,212)"></span></div></div></div><br>-- <br><div dir="ltr" data-smartmail="gmail_signature"><div dir="ltr"><div>Ian C Reese</div><div><a href="https://xycarto.com" target="_blank" rel="noreferrer">https://xycarto.com</a><br></div></div></div></div>
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