[Qgis-user] QGIS performance on large project

[William Kyngesburye]

The slow load problem is more of a general raster problem.  I found that it affected not only loading a project, but also adding rasters and turning on/off raster layers.  Display and zooming were not affected.

Jasper shouldn't affect it that much, as compared to ECW or Kakadu.  There are optimizations in ECW and Kakadu that will affect speed some.

I don't think Qgis (via GDAL) uses Arc's rrd files.  It shouldn't need to as JP2 images have builtin pyramids.

To check if Qgis (GDAL) is using jasper or another JP2 driver, in a Terminal:

gdalinfo --formats

Check if JP2ECW or Jasper (or kakadu) is present.  The MrSID driver can also read JP2, in its default configuration (it's a variant of kakadu), but I disable that in MrSID GDAL plugin for OSX so it doesn't accidentally override ECW or the real Kakadu.

On Jan 23, 2010, at 7:49 AM, Kurt Menke wrote:

> Hello,
> I’m using QGIS as a redistributable platform for a large GIS project that spans all of western North America.  The project has 36 layers 8 of which are large raster datasets (*.img files).  Some of the rasters are ~350mb each.  I’m running the latest version 1.4.0-2.  I am running it on a pretty powerful workstation (windows XP) and am using the osgeo4w version. My primary user is using a MacBook Pro with Leopard and is using the standalone version.  He is experiencing pretty poor performance.  It  moves very very slowly, each operation.  Even turning off/on simple layers is taking up to 45 seconds. This occurs even if there are a handful of base layers turned on.
>  
> I’ve seen some discussion of slow start up issues and raster rendering issues. 
>  
> Would JasPer effect *.img rendering?  If so how can I determine if I or my MacBook user are running that? 
> Does QGIS utilize *.rrd pyramid files generated by ArcGIS?
> I’ve also generated spatial indices for all the vector layers.  Any other suggestions on how to improve performance or test for the bottle neck would be greatly appreciated.
> Thanks
> Kurt
>  
> **************************
> Kurt Menke, GISP
> Bird’s Eye View
> www.BirdsEyeViewGIS.com
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> Cell: 505-362-1776
>  
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-----
William Kyngesburye <kyngchaos*at*kyngchaos*dot*com>
http://www.kyngchaos.com/

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