Create a new table with the extents of the raster tiles and check if it overlaps with your points:
CREATE TABLE rastextets AS SELECT rast::geometry FROM tbl_raster Pierre > -----Original Message----- > From: [email protected] [mailto:postgis-users- > [email protected]] On Behalf Of Jason Mathis > Sent: Tuesday, May 13, 2014 5:56 PM > To: [email protected] > Subject: [postgis-users] getting raster values for point from st_value > > Hi all, > > I have recently loaded a good amount of rasterized shape files into a db. I > mainly used gdal_rasterize and raster2pgsql. The shape files were in NAD83 > so I used the below commands to rasterized and load. > > gdal_rasterize -at -a desc -where "desc='Very High'" -burn 2 -tr 30 30 -ot > byte -a_nodata -99 shape_file.shp raster.tiff > raster2pgsql -d -s 5070 -t 100x100 -F -I -C -Y raster.tiff tbl_raster | psql > -d > raster_db > > I had two sets of shape files one set had about 10 burn values and another > had about 50. The issue is getting these values out of the raster. I believe I > should be using something from this page: > http://postgis.net/docs/RT_ST_Value.html. > > I can visualize this file in QGIS and it looks good, the histogram shows > values. I can also use the postgis functions, st_summarystats or > st_histogram to see some data but I need to be able to query a given point > and return the raster value. > > I have this: > > SELECT ST_Value(rast,(ST_Point( -111.750185, 34.886948))) > FROM tbl_raster > WHERE st_intersects(rast, (ST_Point(-111.750185, 34.886948))) > > Then i thought oh wait should I set the srid?: > > SELECT ST_Value(rast,(ST_SetSRID(ST_Point( -111.750185, > 34.886948),5070))) > FROM tbl_raster > WHERE st_intersects(rast, (ST_SetSRID(ST_Point(-111.750185, > 34.886948),5070))) > > Still I get nothing, then I thought I need to transform so I got this: > > SELECT ST_Value(rast,(ST_Transform(ST_SetSRID(ST_Point( -111.762866, > 34.874309),5070),4326))) > FROM tbl_raster > WHERE st_intersects(rast, (ST_Transform(ST_SetSRID(ST_Point( - > 111.762866, 34.874309),5070),4326))) > > But in the end nothing. > > I did need to add the SRID to the spatial_ref_sys table: > > INSERT into spatial_ref_sys (srid, auth_name, auth_srid, proj4text, srtext) > values ( 5070, 'EPSG', 5070, '+proj=aea +lat_1=29.5 +lat_2=45.5 +lat_0=23 > +lon_0=-96 +x_0=0 +y_0=0 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 > +units=m +no_defs ', 'PROJCS["NAD83 / Conus > Albers",GEOGCS["NAD83",DATUM["North_American_Datum_1983",SPHER > OID["GRS > 1980",6378137,298.257222101,AUTHORITY["EPSG","7019"]],TOWGS84[0, > 0,0,0,0,0,0],AUTHORITY["EPSG","6269"]],PRIMEM["Greenwich",0,AUTHORIT > Y["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG > ","9122"]],AUTHORITY["EPSG","4269"]],PROJECTION["Albers_Conic_Equal_ > Area"],PARAMETER["standard_parallel_1",29.5],PARAMETER["standard_par > allel_2",45.5],PARAMETER["latitude_of_center",23],PARAMETER["longitude > _of_center",- > 96],PARAMETER["false_easting",0],PARAMETER["false_northing",0],UNIT[" > metre",1,AUTHORITY["EPSG","9001"]],AXIS["X",EAST],AXIS["Y",NORTH],AUT > HORITY["EPSG","5070"]]’); > > But ultimately I have nothing I can’t seem to get any data out using a query > with a point value. I am thinking it has to do with the srid? Since I can > visually inspect it and see data. > > Anyone have any hot ideas as to why I am not seeing data? > > Thanks! > > > > This transmission contains confidential and privileged information intended > solely for the party identified above. If you receive this message in error, > you must not use it or convey it to others. Please destroy it immediately > and contact the sender at (303) 386-3955 or by return e-mail to the sender. _______________________________________________ postgis-users mailing list [email protected] http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users
