> I'm trying to use postgis raster analysis and I think that it's incredibly > slow. I > wonder if there is a better raster organization for analysis. > I've tryed both tiled raster and single row raster and tiled raster was a > little bit > faster when calling intersection.
Could you give me a bit more information: What are you intersecting with what? Point, lines, polygons? (lines I guess) How many? How is your raster tiled? How big is it? Did you make sure the right index is used with an EXPLAIN? > I don't really understand the results of the intersection. I expected that the > command would give me a linestring with one coordinate more than the > linestring I gave. But instead it gives me many pieces of linestring. IMHO > it's not > a very usefull result. I'd have to join them to get the profile. What do you expect this information/coordinate to be? The id of the intersecting raster? The mean of the intersecting pixel values? The pixel value for each piece of intersecting line? There is a different query for each and performance is different for each. Here I get people intersecting 100 000 lines with a 300 MB landsat image in 8 minutes and another intersecting 500 000 lidar points in 160 seconds. Do you consider this slow? Also did you read the tutorial? http://trac.osgeo.org/postgis/wiki/WKTRasterTutorial01 In opposition to Jorge answer I must say that the gdal driver is not involved when doing raster/vector intersections in PostGIS. Pierre _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
