> Date: Fri, 30 Mar 2012 10:59:09 -0700 > From: Duarte Carreira <dcarre...@edia.pt> > Subject: [Qgis-user] qgis and big raster catalogs > To: "qgis-user@lists.osgeo.org" <qgis-user@lists.osgeo.org> > Message-ID: > <19FC4FDFEC50D844B20EB1EF42871FCC2E1B5A5B93@IE2RD2XVS421.red002.local> > Content-Type: text/plain; charset="us-ascii" > > Hi Qgisers! > One question: how to get a fast raster catalog in QGIS with a big number of > rasters in it? (in this case 400 ecw) > I am having trouble getting this to work... I tried a vrt catalog and qgis > just hangs when I load it. > Reducing the number of images makes it ok. > Is this a know limitation of gdal/qgis? Is there another approach to catalogs > (not mosaics)? > What is the recommended approach to see a large number of images in QGIS when > working at big scales (zoomed in)? > > I thought of the following: > 1-referenced shapefile catalog - like mapserver tileindex shapefiles > - Qgis does not support this
Do you mean what I described here?: http://lists.osgeo.org/pipermail/qgis-user/2012-March/015804.html Note that if you use an action like I described (instead of using one of the plugins) the exact syntax is probably a little different, depending on what version of QGIS you are running. I gave the syntax for QGIS master, which enabled the new "expression builder" expressions fairly recently. > 2-vrt file > - Qgis is too slow when there are many images in the catalog > 3-referenced catalog in some other format? Sqllite? > - Couldn't find an alternative > 4-just load a directory full of rasters > - I didn't even investigate this option since I figure this would be > painfully slow every time you would load the directory... > One last detail: I'm using ecw images, but I'm betting this is not format > related... _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/qgis-user
