On Sun, Dec 4, 2011 at 12:10 AM, Volkmar Herbst <volkmar.her...@gmx.de> wrote: > Yes, we also do use plr for kriging of soil data, which works very fast, but > there are many different variants of it. It helps to know about geo > statistics and get the right type and formula for the kriging. It is also > possible to do the following steps: > 1. create your grid (in plr) > 2. calculate kriging (in plr) > 3. create contours (in plr) > 4. create contour polygons (I have done it in a postgis function but it > should be also possible in plr) > I abandoned the raster data type as kriging output to postgis as I could not > create the postgis raster from the plr raster in an acceptable time. The > ratser postgis function st_setvalue which works on each pixel takes too long > and there seem to be no other way to set raster values programmatically, > that’s why I switched to contours. We do need array to pixel value or so- > see > http://trac.osgeo.org/postgis/ticket/1228 > Hope that helps
Yes, you are correct about the significant performance issues with calling ST_SetValue for each pixel of a raster. This unfortunately has to do with the deserialization and serialization that occurs every time ST_SetValue is called. Hopefully, I can get to it before the 2.0 code freeze but the outlook doesn't look good. -bborie -- Bborie Park Programmer Center for Vectorborne Diseases UC Davis 530-752-8380 bkp...@ucdavis.edu _______________________________________________ postgis-users mailing list postgis-users@postgis.refractions.net http://postgis.refractions.net/mailman/listinfo/postgis-users
