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<p>Hello,</p>
<p>the issue is not with the performance drawing the raster, it is
with the system only being able to have a certain number of file
based rasters loaded in a project before it will crash.<br>
</p>
<div class="moz-cite-prefix">On 22/11/19 11:08 AM, Alexandre Neto
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CA+H0G_F4PD0jKvJ5EZPzBv-NtmBMtMusZ53yQ4xJKHPMZziQmw@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">AFAIK,
<div><br>
</div>
<div>WMST creates pyramids in cache as needed, hence it may do a
better balance between disk usage and performance. You can
control the number of pyramid layers you create and the
compression format of it to save some space. But having raster
files with 4000x4000 pixels with no pyramids will make a full
read of the raster file to show even only a bit of it... That
will make QGIS performance really poor.</div>
<div><br>
</div>
<div>Thereºs this blog post from 2010 that does some comparison
between several formats and their sizes and performances. It's
in portuguese, but I think you can find ways of translating
it.</div>
<div><br>
</div>
<div><br>
</div>
<div><a
href="https://blog.viasig.com/2010/01/mosaicos-de-imagens-em-mapserver-com-gdal/"
moz-do-not-send="true">https://blog.viasig.com/2010/01/mosaicos-de-imagens-em-mapserver-com-gdal/</a><br>
</div>
<div><br>
</div>
<div>Hope it helps</div>
<div><br>
</div>
<div>Alexandre Neto</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, Nov 21, 2019 at 2:05
PM Patrick Dunford <<a
href="mailto:enzedrailmaps@gmail.com" moz-do-not-send="true">enzedrailmaps@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF">
<p>Building pyramids gobbles up heaps of disk space. I tried
pyramids on 157 MB layer, which created an extra file 1.6
GiB.</p>
<p>I can't see the WMTS building lots of temporary file
pyramids using up disk<br>
</p>
<div>On 18/11/19 10:50 PM, Alexandre Neto wrote:<br>
</div>
<blockquote type="cite">
<div dir="auto">Hi Patrick,
<div dir="auto"><br>
</div>
<div dir="auto">Sorry for asking, did you create
pyramids (overlays) for your raster "tiles"?</div>
<div dir="auto"><br>
</div>
<div dir="auto">See more information about pyramids on
QGIS official documentation:</div>
<div dir="auto"><br>
</div>
<div dir="auto"><a
href="https://docs.qgis.org/3.4/en/docs/user_manual/working_with_raster/raster_properties.html#pyramids-properties"
target="_blank" moz-do-not-send="true">https://docs.qgis.org/3.4/en/docs/user_manual/working_with_raster/raster_properties.html#pyramids-properties</a><br>
</div>
<div dir="auto"><br>
</div>
<div dir="auto">To create pyramids on many files, it's
probably better to use GDAL directly to process all
files in a folder:</div>
<div dir="auto"><br>
</div>
<div dir="auto"><a
href="https://gdal.org/programs/gdaladdo.html"
target="_blank" moz-do-not-send="true">https://gdal.org/programs/gdaladdo.html</a><br>
</div>
<div dir="auto"><br>
</div>
<div dir="auto">My feeling is that the WMS service is
doing that for you, and that's the reason why it works
well with a service.</div>
<div dir="auto"><br>
</div>
<div dir="auto">Alexandre Neto</div>
<div dir="auto">QGIS Support</div>
<div dir="auto"><a href="http://www.qcooperative.net"
target="_blank" moz-do-not-send="true">www.qcooperative.net</a></div>
</div>
<br>
</blockquote>
</div>
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