<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: 514.381.5112 Fax: 514.381.4995<br>
www.archeotec.ca</p>
<div class="gmail_quote">On Jul 30, 2015 7:49 AM, "Radim Blazek-2 [via OSGeo.org] " <<a href="/user/SendEmail.jtp?type=node&node=5217781&i=0" target="_top" rel="nofollow" link="external">[hidden email]</a>> wrote:<br type='attribution'><blockquote style='border-left:2px solid #CCCCCC;padding:0 1em' class="quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
On Thu, Jul 30, 2015 at 11:36 AM, Andrea Peri <<a href="/user/SendEmail.jtp?type=node&node=5217747&i=0">[hidden email]</a>> 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 /><div><div class='shrinkable-quote'><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]</a>>:
<br />>> On Thu, Jul 30, 2015 at 9:19 AM, Andrea Peri <<a href="/user/SendEmail.jtp?type=node&node=5217747&i=2">[hidden email]</a>> 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 />>>> <a href="/user/SendEmail.jtp?type=node&node=5217747&i=3">[hidden email]</a>
<br />>>> <a href="http://lists.osgeo.org/mailman/listinfo/qgis-user" target="_top" rel="nofollow" link="external">http://lists.osgeo.org/mailman/listinfo/qgis-user</a><br />>
<br />>
<br />>
<br />> --
<br />> -----------------
<br />> Andrea Peri
<br />> . . . . . . . . .
<br />> qwerty àèìòù
<br />> -----------------
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