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<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black">Hello all,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black">I think I've found an edge case in gdal.Dataset.BuildOverviews. I'm using GDAL 3.0.4 and have found that some of our BuildOverviews tests were crashing out with a seg fault. On investigation,
it seems to be when COMPRESS_OVERVIEW is set to LZW, the height is greater than the width, and the overview list is long enough that we will end up with some 1x1 overviews. Here is a code snippet that reproduces the crash.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">from osgeo import gdal<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">gdal.SetConfigOption('COMPRESS_OVERVIEW', 'LZW')<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">temp_path = '/tmp/test.tif'<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">drv = gdal.GetDriverByName('GTiff')<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">raster_ds = drv.Create(temp_path, 5, 6, 1, gdal.GDT_Int16)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">del raster_ds<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">tif = gdal.OpenEx(temp_path, gdal.GA_ReadOnly)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black">tif.BuildOverviews('nearest', overviewlist=[2, 4, 8])<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New";color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black">The data type doesn't seem to matter (I've also tried Float32), but it seems that the raster dimensions are important. I couldn't get it to fail if the width was equal to or greater
than the height.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black">Thanks,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black">Jon<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:black"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-family:"Arial",sans-serif;color:black;mso-fareast-language:EN-GB">Jon Morris<o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:#F6A124;mso-fareast-language:EN-GB">Software Developer<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:#F6A124;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span style="font-family:"Arial",sans-serif;color:#F6A124;mso-fareast-language:EN-GB"><a href="sip:jon.morris@jbarisk.com"><span style="color:#F6A124;text-decoration:none">Skype</span></a><o:p></o:p></span></b></p>
<p class="MsoNormal"><span style="color:black;mso-fareast-language:EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><i><span style="font-size:12.0pt;color:black;mso-fareast-language:EN-GB">COVID-19. During the current outbreak JBA remains open for business and we continue to deliver our services. However, we have adopted flexible/remote workingas required.
I will be receiving and reading email as normal but I may not always be available on the office number.</span></i><span style="color:black;mso-fareast-language:EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p><a href="https://www.jbagroup.co.uk/sites/www.jbagroup.co.uk/files/documents/15-030%20JBA%20Business%20Continuity%20Briefing%20-%20Latest.pdf"><img src="https://www.jbagroup.co.uk/imgstore/covid19footer.png" alt="JBA COVID-19 statement"></a></p>
<p><strong><span style="color: #f6a125; font-family:arial;">T</span></strong><span style="text-decoration: none; color: #000000; font-family:arial;"> +44 (0) 1756 799919</span><br>
<a style="text-decoration: none; color: #f6a125; font-family:arial;" href="http://www.jbarisk.com">www.jbarisk.com</a></p>
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<p class="MsoNormal"><span style="font-family:"Arial",sans-serif;color:#FF9C00">Our postal address and registered office is JBA Risk Management</span><span style="font-family:"Arial",sans-serif;color:black">
</span><span style="font-family:"Arial",sans-serif;color:#FF9C00">Limited, 1 Broughton Park, Old Lane North, Broughton, Skipton, North Yorkshire BD23 3FD.</span><o:p></o:p></p>
<p><b><span style="background: white; color: black; font-family: "Arial",sans-serif; font-size: 10pt;">Find out more about us here:
<a href="http://www.jbarisk.com/"><font color="#0563c1">www.jbarisk.com</font></a> and
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<p><span style="background: white; color: black; font-family: "Arial",sans-serif; font-size: 8pt;">The JBA Group supports the JBA Trust.</span></p>
<p style="margin: 0cm 0cm 0pt;"><span style="background: white; color: rgb(68, 68, 68); font-family: "Arial",sans-serif; font-size: 8pt;">All JBA Risk Management's email messages contain confidential information and are intended only for the individual(s) named.
If you are not the named addressee you should not disseminate, distribute or copy this e-mail.</span><br>
<span style="color: rgb(68, 68, 68); font-family: "Arial",sans-serif; font-size: 8pt;"><span style="background: white;">Please notify the sender immediately by email if you have received this email by mistake and delete this email from your system.</span></span><br>
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<p style="margin: 0cm 0cm 0pt;"><span style="color: rgb(68, 68, 68); font-family: "Arial",sans-serif; font-size: 8pt;"><span style="background: white;">JBA Risk Management Limited is registered in England, company number 07732946, 1 Broughton Park, Old Lane
North, Broughton, Skipton, North Yorkshire, BD23 3FD, </span></span><span style="background: white; color: black; font-family: "Arial",sans-serif; font-size: 8pt;">Telephone: +441756799919</span></p>
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