On Jan 18, 2010, at 6:09 AM, Craig Leat wrote: > Greg Coats wrote: >> Using Qgis version 1.4.0 built against code revision 12644:12645M >> from http://www.kyngchaos.com under Mac OS X 10.6.2, I find that >> starting up from the .qgs project file takes 4 minutes, and during this >> time Activity Monitor reports that Qgis is consuming 99% of the CPU. >> The largest file in the project is only 37 MB. The computer has a 2.33 >> GHz Intel Core 2 Duo processor, with 3 GB RAM. AFTER start up, Qgis >> quickly pans and zooms in and out through the imagery. Only ONE >> raster image is drawn at any particular scale. What is Qgis doing at >> start up that requires it to use 99% of the CPU for 4 consecutive >> minutes? What can be done to reduce the start up time? I am >> interested in hearing from others how long Qgis takes to start up. > > Four minutes to startup! Not bad, considering I have project files > taking ~25 minutes to load. I haven't read the code :-) but my > impression is that QGIS scans every raster file when the project is > opened to collect essential information it needs to interact with the > files. It's not only file size that's important, but also the number > of files. There was a suggestion on this list or the developer list > (can't remember) some time ago (September 2009?) that pointed to > combining several rasters into a virtual catalogue (gdal vrt) to > improve performance. In my tests performance actually dropped by a > factor of three, but your mileage may vary. I suggest you experiment a > bit. > > A question to any devs following this. Is it practical to write the > information QGIS collects at startup into the project file or another > file to have it readily available the next time the project is loaded? > I was able to shave off a minute or so by making sure all the vrt rasters had custom min/max set in the rendering propoerties.
I alos noticed that it takes a while to turn off and on the vrt rasters, and open their properties windows. ----- William Kyngesburye <kyngchaos*at*kyngchaos*dot*com> http://www.kyngchaos.com/ [Trillian] What are you supposed to do WITH a maniacally depressed robot? [Marvin] You think you have problems? What are you supposed to do if you ARE a maniacally depressed robot? No, don't try and answer, I'm 50,000 times more intelligent than you and even I don't know the answer... - HitchHiker's Guide to the Galaxy _______________________________________________ Qgis-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-user
