[Qgis-developer] slow raster loading

[Marco Hugentobler]

Btw, is it possible to call computeMinMax() on demand, e.g. in 
QgsGDALProvider::minimumValue /maximumValue instead of the provider 
constructor?

It probably does not matter much for the desktop experience. However, for 
server throughput, avoidance of opening and parsing the aux.xml file could make 
a difference.

Regards,
Marco


Am Dienstag, 9. August 2011, 21.46:45 schrieb Tim Sutton:
> Hi Paolo
> 
> Does it do that every time you load that layer or only the first time?
> Does the filesystem permissions allow writing of gdal .aux.xml files?
> 
> My raster stats branch merge changed some behaviours and it is
> probably a side effect of that. One of the changes is that gdal gets
> full stats when trying to determine the min max of a band. It will
> fetch those stats quickly from aux.xml if present of if not its going
> to do a full stats gather just for the basic min max stats which is
> where you probably experience the slowness. I will see if I can find a
> better way to do the basic min/max stats gathering.
> 
> Regards
> 
> Tim
> 
> On Tue, Aug 9, 2011 at 3:49 PM, Paolo Cavallini <cavallini at faunalia.it> 
wrote:
> > Hi all.
> > With current master, I get bad performances in loading rasters (a <12Mb
> > takes >5 sec); when double-clicking it from the QGIS browser, it is far
> > slower (>20 sec). From the console:
> > Warning: Object::connect: No such signal QgsGdalProvider::statusChanged(
> > QString ) in
> > /storage/build/Quantum-GIS/src/core/raster/qgsrasterlayer.cpp:2446 Any
> > hint?
> > All the best.
> > --
> > Paolo Cavallini: http://www.faunalia.it/pc
> > _______________________________________________
> > Qgis-developer mailing list
> > Qgis-developer at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/qgis-developer


-- 
Dr. Marco Hugentobler
Sourcepole -  Linux & Open Source Solutions
Churerstrasse 22, CH-8808 Pfäffikon SZ, Switzerland
marco.hugentobler at sourcepole.ch http://www.sourcepole.ch
Technical Advisor QGIS Project Steering Committee