[Qgis-user] raster stats

[John Callahan]

Does anyone has information on the progress of this ticket?  From reading
the comments on the the ticket, it looks as though there are some
possibilities for enhancement.

I use rasters regularly so this issue comes quite often.  For one
particular 10GB DEM (in IMG format) it takes 7 or 8 minutes to calculate
stats in QGIS, which takes a while when it happens every time I open that
file.  Stats have already been computed through gdalinfo.  Thanks for any
information.

- John





On Thu, Apr 14, 2011 at 7:24 AM, Radim Blazek <radim.blazek at gmail.com>wrote:

New ticket http://trac.osgeo.org/qgis/ticket/3735
>
> Radim
>
> On Mon, Mar 21, 2011 at 4:37 PM, John Callahan <john.callahan at udel.edu>
> wrote:
> > I'm not sure if this behavior is expected or I am missing something.
> >
> > I have a 1 band raster dataset (an elevation DEM) in TIF format.  It has
> > statistics computed from "gdalinfo -stats mydata.tif"   However, when I
> open
> > it in QGIS (both 1.6 and 1.7 trunk), and look at the Metadata tab in
> Layer
> > properties, there are two sections that contain band stats information.
> The
> > first section is labeled "Band 1" and lists the same stats as found using
> > gdalinfo.  The second section is labeled "Band" and says "No stats
> collected
> > yet" for band 1.  QGIS has to create the stats when I apply a color map
> or
> > stretch.  For large rasters, this takes a while, and must be done each
> time
> > it's used in QGIS.
> >
> > Has anyone experienced this behavior?  Is this expected?  Is there a way
> to
> > let gdal compute all the stats that QGIS needs?  Thanks.
> >
> > - John
> >
> > **************************************************
> > John Callahan, Research Scientist
> > Delaware Geological Survey, University of Delaware
> > URL: http://www.dgs.udel.edu
> > **************************************************
> >
> > _______________________________________________
> > Qgis-user mailing list
> > Qgis-user at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/qgis-user
> >
> >
>
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