On Thu, Aug 23, 2012 at 11:00 AM, Even Rouault <[email protected]> wrote: > Selon Etienne Tourigny <[email protected]>: > >> It would be nice to have this bultin to gdalbuildvrt (as an optin of >> course) - could the authors make a patch? > > For a *byte* data type, which must be the common case, why wouldn't QGIS just > use min=0 and max=255 when statistics are not computed ?
good question. Unless I am mistaken, min/max are set to 0/255 by default, unless QgsRasterDataProvider::bandStatistics() or QgsRasterLayer::bandStatistics() is called - which is probably what happens. I don't understand what is the problem, does the VRT load slowly initially, or is getting statistics rather slow? On the other hand, wouldn't a simple "gdalinfo -stats file.vrt" achieve the same as the linked python script, but easier to run? Etienne > >> >> Regards, >> Etienne >> >> On Thu, Aug 23, 2012 at 7:34 AM, Micha Silver <[email protected]> wrote: >> > On 23/08/2012 11:33, Giovanni Manghi wrote: >> >> >> >> http://trac.osgeo.org/gdal/wiki/CatalogueForQIS >> > >> > >> > Magic! Many thanks, and also to Andrea Peri for posting the python code. >> > In windows I had to run it as: " python computestats.py -approx >> > <filename.vrt> " >> >> >> >> it would be very nice to have this added as tool directly in QGIS... >> >> >> >> cheers >> >> >> >> >> >> -- Giovanni -- >> >> >> >> >> >> On Thu, 2012-08-23 at 11:27 +0300, Micha Silver wrote: >> >>> >> >>> Hello all: >> >>> >> >>> I have a batch of over 100 raster tiles in ecw format. Each is 50 - >> >>> 100 MB in size. When I choose 20 or so files to load they appear >> >>> (render) very quickly - in a matter of a few seconds or less. If I >> >>> create a vrt of that same batch of tiles, it takes a long time to >> >>> first render - upwards of 15 - 30 seconds. Once the vrt is loaded >> >>> response is excellent (zooming, etc). But that initial delay is a bit >> >>> annoying. Anything I can do to improve it? (QGIS 1.8, Win 7 64 bit) >> >>> >> >>> Many thanks, >> >>> Micha >> >>> >> >>> -- >> >>> Micha Silver >> >>> 052-3665918 >> >>> _______________________________________________ >> >>> Qgis-user mailing list >> >>> [email protected] >> >>> http://lists.osgeo.org/mailman/listinfo/qgis-user >> >> >> >> >> >> >> >> This mail was received via Mail-SeCure System. >> >> >> >> >> > >> > >> > -- >> > Micha Silver >> > 052-3665918 >> > >> > _______________________________________________ >> > Qgis-user mailing list >> > [email protected] >> > http://lists.osgeo.org/mailman/listinfo/qgis-user >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> > > _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
