[QGIS-trac] [Quantum GIS] #3588: new raster provider: very slow

[Quantum GIS]

#3588: new raster provider: very slow
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   Reporter:  lutra                             |              Owner:  rblazek      
       Type:  bug                               |             Status:  new          
   Priority:  major: does not work as expected  |          Milestone:  Version 1.7.0
  Component:  Rasters                           |            Version:  Trunk        
   Keywords:                                    |   Platform_version:               
   Platform:  All                               |           Must_fix:  Yes          
Status_info:  0                                 |  
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 I'm testing the new raster capabilities of QGIS with bunch of big tiff
 rasters (> 1gb, sometimes > 2gb), with internal tiles and/or overviews.

 What I'm seeing is that now those rasters take quite a *lot* (making
 qgis not responsive for a while) to be rendered, before the merge it was
 all *much* quicker.

 As exemple:

 on QGIS 1.6 a 1.7GB geotiff with tiles and overviews opens in (more or
 less) 1 sec., in trunk now takes (more os less) 1 minute!


 After the raster show in the canvas, also opening its properties take a
 long time. Before the merge was immediate.

 Zooming and panning it is also much slower than before the merge.

 Overall it seems like that tiles and overviews are ignored or not read,
 but to me seems that also opening big tiffs (> 1gb) without internal tiles
 and/or overviews takes a *lot* more than before the merge.

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Ticket URL: <https://trac.osgeo.org/qgis/ticket/3588>
Quantum GIS <http://qgis.org>
Quantum GIS is an Open Source GIS viewer/editor supporting OGR, PostGIS, and GRASS formats