Waoo ! Real nice. Thank you for this work.
Nicolas On 29 June 2010 17:29, Pierre Racine <[email protected]> wrote: > Hi everybody, > > I'm pleased to announce that you can now do intersections between rasters and > geometries very much like you used to do geometry/geometry intersections in > PostGIS. For this, PostGIS WKT Raster introduces two new functions to > PostGIS: ST_Intersects(geometry, raster, band) and ST_Intersection(geometry, > raster, band). > > As its geometry/geometry sister, ST_Intersects(geometry, raster, band) > returns TRUE if the withvalue area of a raster or a raster tile (nodata value > are ignored) intersects a geometry and ST_Intersection(geometry, raster, > band) returns the geometry/value set of geometries representing the > intersection between the geometry and each polygonized group of pixel sharing > a same value from the raster and its associated value. Example: > > SELECT polyid, > (ST_Intersection(the_geom, rast)).geom, > (ST_Intersection(the_geom, rast)).val > FROM my_polygons, srtm_tiled > WHERE ST_Intersects(rast, the_geom) > > or, a bit more complex, but much faster and returning the same result: > > SELECT polyid, (gv).geom, (gv).val > FROM (SELECT polyid, ST_Intersection(the_geom, rast, 1) AS gv > FROM my_polygons, srtm_tiled > WHERE ST_Intersects(rast, the_geom)) foo > > These functions works with any kind of geometry so you can intersect any > road, river, polygons or point layer with your favorite elevation or land > cover raster of any resolution and any size. You can also load any number of > raster in the database with one command line to constitute a unique table > raster coverage of any shape (no matter if your group of raster do not form a > rectangular coverage). > > You will find a complete tutorial on how to use those two new functions here: > http://trac.osgeo.org/postgis/wiki/WKTRasterTutorial01. A reference is > available here: > http://postgis.refractions.net/documentation/manual-svn/RT_reference.html and > chapter 13 of "PostGIS in Action" is also a very good introduction to WKT > Raster. > > Compilation and installation info are available in the project home page: > http://trac.osgeo.org/postgis/wiki/WKTRaster > > These features are the result of two years of collaboration between many > people and companies interested in bringing raster into PostGIS. I would like > to thanks particularly Steve Cumming who initially made all this possible, > Sandro Santilli who wrote the base code, Mateusz Loskot who wrote the Python > loader, Jorge Arevalo who wrote the GDAL driver and ST_DumpAsPolygons(), > Regina and Leo Obe who are doing so many things and believed in the project > from the beginning by adding a chapter about WKT Raster in "PostGIS in > Action" and also David Zwarg who wrote most of the setter functions. > > This is the first step toward a first complete raster/vector analysis and > manipulation SQL API. We hope to make of PostGIS with WKT Raster the most > powerful and complete GIS analysis and manipulation high level language ever > (!!!). WKT Raster should normally be totally integrated into PostGIS in > PostGIS release 2.0. Upcoming functions should include ST_Reclass, ST_Clip, > ST_AsRaster, ST_Resample. > > Let us know your need and your experience with WKT Raster. > > Thanks, > > Pierre Racine > > _______________________________________________ > postgis-users mailing list > [email protected] > http://postgis.refractions.net/mailman/listinfo/postgis-users > _______________________________________________ postgis-users mailing list [email protected] http://postgis.refractions.net/mailman/listinfo/postgis-users
