Thanks Pierre, *SELECT o.osm_id, ST_AsText((ST_Intersection(ST_Transform(o.way,4326), s.rast)).geom), (ST_Intersection(ST_Transform(o.way,4326), s.rast)).val FROM planet_osm_line o, srtm_tiled_4326 s WHERE ST_Intersects(ST_Transform(o.way,4326), s.rast) and o.highway = 'primary';
osm_id; intersecting linestring, elevation (mts) 16815326;"LINESTRING(8.58333333333333 56.2074149493615,8.58261220053766 56.2066666666667)";45* *..* *..* I get to see the elevation now for my geometry and raster. I now want to introduce some artificial points that are equidistant (say 10 mts apart) on each road segment.. and then compute their intersection with the raster. Is it better to first divide the lines into such points and then compute their intersections with the raster? Or break the linestring that I get back after intersection? I have an idea of how I might be able to do this, but just wanted to confirm what will perform better. Cheers, Ed * * * * On Tue, Feb 28, 2012 at 4:28 PM, Pierre Racine <pierre.rac...@sbf.ulaval.ca>wrote: > > What I wish to now do is to use those spot heights to create an > elevation raster > > layer via which all NoDataValued pixels have an elevation set that is > interpreted > > from the spot heights around it. > > > > Has anyone any suggestions as to how this can be done by PostGIS's > ST_Raster? > > (ST_MapAlgebra perhaps etc?) > > We don't have any interpolation algorithm yet. But we have > ST_MapAlgebraFctNgb() which compute pixels value as focal functions (or > moving windows). I not sure to which degree you can implement interpolation > with moving windows but if your points are close to each other enough you > could compute the mean of the point surrounding each point. Have a look at: > > > http://postgis.refractions.net/documentation/manual-svn/RT_ST_MapAlgebraFctNgb.html > > Pierre > _______________________________________________ > postgis-users mailing list > postgis-users@postgis.refractions.net > http://postgis.refractions.net/mailman/listinfo/postgis-users >
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