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<p class="MsoNormal"><a name="x__MailAutoSig"><span style="font-family:"Arial",sans-serif">Hi all,</span></a><span style="font-family:"Arial",sans-serif"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">I’ve recently tried enabling the GDAL_FORCE_CACHING option, and found it gives some significant improvements to TIFF/VRT read speeds.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">However, using GDAL 2.3.0, I’ve now found that when reading large VRTs, I can sometimes get subtly different values – up to about 1% summed difference across a 1000x1000 or so area. Is there
a known issue in GDAL_FORCE_CACHING in this older version of GDAL, or alternatively have I misunderstood the use of this option and is this expected behaviour?<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Arial",sans-serif">Daniel<o:p></o:p></span></p>
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<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>
<p><a href="http://www.jbarisk.com"><img src="http://www.jbagroup.co.uk/imgstore/JBA-Email-Sig-Icons-JBA.png" alt="Visit our website" width="33" height="26"></a> <a href=""><img src="http://www.jbagroup.co.uk/imgstore/JBA-Email-Sig-Icons-LINKEDIN.png" alt="" height="26"></a>
<a href="https://twitter.com/jbarisk"><img src="http://www.jbagroup.co.uk/imgstore/JBA-Email-Sig-Icons-TWITTER.png" alt="Follow us on Twitter" width="33" height="26"></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
</span></b><b><span style="background: white; color: rgb(68, 68, 68); font-family: "Arial",sans-serif; font-size: 10pt;"><a href="http://twitter.com/JBARisk" target="_blank"><font color="#0563c1">follow us on Twitter @JBARisk</font></a> and
<a href="https://www.linkedin.com/company/2370847?trk=tyah&trkInfo=clickedVertical%3Acompany%2CclickedEntityId%3A2370847%2Cidx%3A2-1-2%2CtarId%3A1447414259786%2Ctas%3AJBA%20RISK%20MANAGEMENT">
<font color="#0563c1">LinkedIn</font></a> </span></b></p>
<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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