<div dir="ltr">Spinning disks can be significantly slower than an SSD :( However, I've opened 10GB, 3-band rasters off spinning platter disks in seconds, so :-\ Some calculations on band cutoffs and things can take a while if I ask it to calculate those.</div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jul 30, 2015 at 9:50 AM, Nicolas Cadieux <span dir="ltr"><<a href="mailto:nicolas.cadieux@archeotec.ca" target="_blank">nicolas.cadieux@archeotec.ca</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><p dir="ltr">Hi,</p>
<p dir="ltr">I have been opening rasters that are much bigger than that lately with no trouble at all. It does take some time but not hours. I have bigger file (80-300GB) but with one band only. I do use a SSD to help out but works with a usb3 drive also.</p>
<p dir="ltr">The obvious is to check for to see if there is a problem with the hardware (memory, CPU, drive) and to make sure you are not opening the file from a file server (a virtual drive) but from a local hard drive (not a USB key) or a failing HD. </p>
<p dir="ltr">Try zooming on the zone using a small polygons as a reference, before opening the raster. Try disabling the "screen render" before opening the raster (right lower corner or Option\Rendering\Rendering behavior.</p>
<p dir="ltr">An other potential problem is the way the tiff was created. If, for example the file was created with gdal-Grid (interpolation), then by default, the file was created with an origin from the bottom-left and not upper-left.</p>
<p dir="ltr">Try resaving the file in QGIS. Try using the QGIS usual method of saving rasters and also try using gdal-warp with no parameters (raster/projections/warp) (that with change the file origin) then reopen the file. <br></p>
<p dir="ltr">Nicolas Cadieux M.Sc.<br>
Les Entreprises Archéotec inc. <br>
8548, rue Saint-Denis Montréal H2P 2H2<br>
Téléphone: <a href="tel:514.381.5112" value="+15143815112" target="_blank">514.381.5112</a> Fax: <a href="tel:514.381.4995" value="+15143814995" target="_blank">514.381.4995</a><br>
<a href="http://www.archeotec.ca" target="_blank">www.archeotec.ca</a></p>
<div class="gmail_quote">On Jul 30, 2015 7:49 AM, "Radim Blazek-2 [via OSGeo.org] " <<a href="http:///user/SendEmail.jtp?type=node&node=5217781&i=0" rel="nofollow" link="external" target="_blank">[hidden email]</a>> wrote:<br type="attribution"><blockquote style="border-left:2px solid #cccccc;padding:0 1em"><span class="">
On Thu, Jul 30, 2015 at 11:36 AM, Andrea Peri <<a href="/user/SendEmail.jtp?type=node&node=5217747&i=0">[hidden email]> wrote:
<br>> Hi Radim,
<br>> thx for hint.
<br>>
<br>> I try to set the contrast enhancement to NO STRETCH
<br>> and
<br>> Limits to minimum / maximum ,
<br>> Apparently seem to have no result. The qgis is locked in opening of
<br>> raster, but of course I should wait for some hours to see if some
<br>> improvements is occursed.
<br><br>You can try to uncheck Options > Canvas & Legend > Layer Legend >
<br>Create raster icons
<br>but I don't think that it could help if zoom/pan is fast, so it seems
<br>that there are overviews (pyramids). In fact, even with cumulative cut
<br>it should not be slow if there are overviews because default cut
<br>calculation is using estimated histogram (250000 pixels).
<br><br>The file is on local hard disk?
<br><br>Do you see what is happening from debug output?
<br><br>If you save a project with the raster, the next load of the project is fast?
<br><br>Radim
<br><br></span><div><div><br>> A.
<br>>
<br>>
<br>> 2015-07-30 9:52 GMT+02:00 Radim Blazek <<a href="/user/SendEmail.jtp?type=node&node=5217747&i=1">[hidden email]>:
<br><div><div class="h5">>> On Thu, Jul 30, 2015 at 9:19 AM, Andrea Peri <<a href="/user/SendEmail.jtp?type=node&node=5217747&i=2">[hidden email]> wrote:
<br>>>> Hi,
<br>>>>
<br>>>> I have a GeoTiff raster of 24Gbyte, floating point (Float64) with 11
<br>>>> bands and fomat geotiff.
<br>>>>
<br>>>> When try to open it with qgis 2.8.1 I see it take a really uge time to
<br>>>> open it (about 10 hours).
<br>>>> Initially I guess that was a time due to the huge dimension, but after
<br>>>> the qgis show it.
<br>>>> I notice that it is reallyquickly to zoom and pan.
<br>>>> I don't understand why this difference between the open time and zoom/pan time.
<br>>>>
<br>>>> My first suspect was that qgis want to calculate the statistics in first open.
<br>>>> But after a check with gdalinfo I see the statistics are available
<br>>>> also in original tiff.
<br>>>
<br>>> QGIS defaults are stretch to 2/98% cut, try to set in
<br>>> Options > Rendering > Rasters
<br>>> Contrast enhancement: No stretch or Limits: Minimum / maximum
<br>>>
<br>>> Radim
<br>>>
<br>>>
<br>>>> So I dont know really why it take so more time to open it.
<br>>>>
<br>>>> I hope to find some setting to reduce the pen time for this kind of images.
<br>>>>
<br>>>> Thx,
<br>>>>
<br>>>> A.
<br>>>>
<br>>>> --
<br>>>> -----------------
<br>>>> Andrea Peri
<br>>>> . . . . . . . . .
<br>>>> qwerty àèìòù
<br>>>> -----------------
<br>>>> _______________________________________________
<br>>>> Qgis-user mailing list
<br></div></div>>>> <a href="/user/SendEmail.jtp?type=node&node=5217747&i=3">[hidden email]
<br>>>> <a href="http://lists.osgeo.org/mailman/listinfo/qgis-user" rel="nofollow" link="external" target="_blank">http://lists.osgeo.org/mailman/listinfo/qgis-user</a><span class=""><br>>
<br>>
<br>>
<br>> --
<br>> -----------------
<br>> Andrea Peri
<br>> . . . . . . . . .
<br>> qwerty àèìòù
<br>> -----------------
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