Thanks for responding. Could you outline how I would go about doing a partitioned table structure? My only concern with tile size is processing time. Most of my queries will involve areas of less than 1 mi^2, and I would clip the data into that shape. I just don't know where to start! There's not too many resources online/print dealing with postgis rasters in detail.
On Tue, Jul 23, 2013 at 12:57 PM, Bborie Park <[email protected]> wrote: > You may not need to drop all the constraints when adding additional data > to the table. You most likely will need to drop is the maximum extent > constraint. Assuming the input rasters have the same scale, skew and SRID > as that found in the table, you don't need to drop those corresponding > constraints. > > If you're going to do the continental US at a fine resolution (e.g. 1 > meter), you do NOT want to put all the rasters in one table. You'll want to > use a partitioned table structure and should consider a bigger tile size > (depending on your hardware). > > -bborie > > > On Tue, Jul 23, 2013 at 10:43 AM, Jayson Gallardo > <[email protected]>wrote: > >> I've looked and looked, but I have not been able to find an answer to my >> question. I have downloaded elevation data for the state of Arkansas (in >> the form of multiple tiles), and used raster2pgsql to upload it into a >> single table: >> >> raster2pgsql -I -C -e -F -t 50x50 -l 2,4 n*/grdn* public.dem_elevation | >> psql -U postgres -d testdb -h localhost -p 5432 >> >> I did this because I didn't know how to pull the data if they were in >> separate tables. Now, however I would like to add elevation data for other >> areas. I tried to just add it to the current table, but that required >> dropping the constraints which for such a huge amount of data seems to take >> a long time (I let it run for 24+ hours and it didn't finish). So, my >> question is, if I load all my rasters as individual tables, how could I run >> something similar to this query on them all (from a python script): >> >> SELECT ST_AsGDALRaster(ST_CLIP(ST_Union(rast), >> ST_GeomFromText(WKT,900913)),'GTiff') FROM "dem_elevation" WHERE >> ST_Intersects(rast, ST_Transform(ST_GeomFromText(WKT,900913),4269)) >> >> My goal, if it's not obvious, is to clip elevation data and export it to >> a GTiff format and perform some operations on that raster data. Eventually, >> I would like to put the whole continental US elevation data into my >> database, so I need to be able to do so, while still being able to query >> them based on an area of interest the user selects from a map. I started >> working with PostGIS and Mapserver last month, so please forgive my >> ignorance on such topics. Thanks in advance >> >> _______________________________________________ >> postgis-users mailing list >> [email protected] >> http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >> >> > > _______________________________________________ > postgis-users mailing list > [email protected] > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users > >
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