[gdal-dev] [Qgis-developer] Large raster (ecw) identify very long

[Radim Blazek]

On Fri, Aug 24, 2012 at 10:45 PM, Even Rouault
<even.rouault at mines-paris.org> wrote:
> I've tested the big ECW (1.8 GB, 141970 x 141970) provided by Jukka and could
> indeed reproduce a noticable performance issue when simulating picking with my
> tiny GDAL python script. In QGIS, the performance was still OK however, a few
> hundreds of milliseconds for each picking. It is just when you do a lot of
> iterations that you begin to notice the slowness, or if the dataset is really
> huge.
>
> I've fixed that in http://trac.osgeo.org/gdal/ticket/4790 in trunk and 1.9
> branch. So it will be in GDAL 1.9.2. Actually, as I think that the ECW driver
> is generally available through a plugin (and not built-in in GDAL DLL), this
> could be available sooner if the ECW plugin is rebuilt with the fixed sources.

Thanks,
QGIS is now using 2x2 only if following condition is matched:

#if !defined(GDAL_VERSION_NUM) || GDAL_VERSION_NUM < 1920
      if ( strcmp( GDALGetDriverShortName( GDALGetDatasetDriver(
mGdalDataset ) ), "ECW" ) == 0 )

Radim

> Best regards,
>
> Even