<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Fri, Dec 16, 2016 at 1:52 PM, Even Rouault <span dir="ltr"><<a href="mailto:even.rouault@spatialys.com" target="_blank">even.rouault@spatialys.com</a>></span> wrote:<br><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 style="font-family:monospace;font-size:9pt;font-weight:400;font-style:normal"><span class="gmail-">
<p style="margin:0px;text-indent:0px"> </p>
<p style="margin:0px;text-indent:0px">> Wondering if when generating overviews we still have a problem similar to</p>
<p style="margin:0px;text-indent:0px">> the one you have fixed in 2.0 or some data-updating issue.</p>
<p style="margin:0px;text-indent:0px">> </p>
<p style="margin:0px;text-indent:0px">> These are my hypothesis on what is going on.</p>
<p style="margin:0px;text-indent:0px">> A simple translate with no overviews makes the file ending at 0x7555 with</p>
<p style="margin:0px;text-indent:0px">> offset of next IFD saying 0x0000.</p>
<p style="margin:0px;text-indent:0px">> When you add overviews, it writes a new IFD at 0x7556 with TAG entries,</p>
<p style="margin:0px;text-indent:0px">> then it encodes something and then it writes a new IFD.</p>
<p style="margin:0px;text-indent:0px">> At the end, it goes back updating the offset of the 1st overview IFD</p>
<p style="margin:0px;text-indent:0px">> (0xBBF0) making the one at 0x7556 being not referred anymore.</p>
<p style="margin:0px;text-indent:0px">> Does it make sense?</p>
<p style="margin:0px;text-indent:0px">> </p>
<p style="margin:0px;text-indent:0px"> </p>
</span><p style="margin:0px;text-indent:0px">With JPEG compression right ?</p></div></blockquote><div>Right,</div><div>Indeed, before sending my previous email I have also tried with:<br></div><div><i>gdaladdo -r average --config COMPRESS_OVERVIEW DEFLATE --config PHOTOMETRIC_OVERVIEW RGB</i><br></div><div>to understand if it was related to JPEG only but, even with these options, the output overviews were jpeg compressed (I assume there is some kind of coherency check in gdaladdo).<br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="font-family:monospace;font-size:9pt;font-weight:400;font-style:normal"><p style="margin:0px;text-indent:0px"> I do reproduce something similar to your findings in 2.1 indeed. This no longer happens in trunk due to related improvements (<a href="https://trac.osgeo.org/gdal/wiki/CloudOptimizedGeoTIFF" target="_blank">https://trac.osgeo.org/gdal/<wbr>wiki/CloudOptimizedGeoTIFF</a>), I made in the last couple of weeks (using the same trick of creating a in-memory TIFF file to get the JPEG tables and set them direcly on the overview IFD at creation time).</p><span class="gmail-">
<p style="margin:0px;text-indent:0px"> </p></span></div></blockquote><div>Do you think this will be available in other series or does it introduce new API/major changes which makes it available on 2.2.x only?</div><div>Thanks again for your precious feedbacks.</div><div><br></div><div>Cheers,</div><div>Daniele</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div style="font-family:monospace;font-size:9pt;font-weight:400;font-style:normal"><span class="gmail-">
<p style="margin:0px;text-indent:0px">Even</p>
<p style="margin:0px;text-indent:0px"> </p>
<p style="margin:0px;text-indent:0px"> </p>
<p style="margin:0px;text-indent:0px">-- </p>
<p style="margin:0px;text-indent:0px">Spatialys - Geospatial professional services</p>
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