Congratulations on the great job done! George
On Tue, Jun 29, 2010 at 12:55 PM, Nicolas Ribot <[email protected]>wrote: > 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.htmland > 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 > -- George R. C. Silva Desenvolvimento em GIS http://blog.geoprocessamento.net
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