Hi, I noticed that the OSM data is using srid = 900913. So I reloaded the tif files as the same srid, yet no luck with the intersection query! :( *ALTER TABLE public.planet_osm_line ADD COLUMN way geometry(LineString,900913); * Cheers, Ed On Mon, Feb 27, 2012 at 3:25 PM, Ed Linde <edoli...@gmail.com> wrote:
> Hi Pierre, > I used --> */root/postgis-svn/raster/loader/raster2pgsql -s 4326 -t 50x50 > -I *.tif public.srtm_tiled > elev.sql* > for the loading. The switch in args did not make a difference > unfortunately! :( > I am pretty sure that the OSM roads geometry used SRID = 4326, and I think > the arguments I have > used to get in the tif files with the -s option also is right. > One warning I got while loading was (maybe it makes sense to you?) : > > */root/postgis-svn/raster/loader/raster2pgsql -s 4326 -t 50x50 -I *.tif > public.srtm_tiled > elev.sql > *Processing 1/4: srtm_38_01.tif > Processing 2/4: srtm_38_02.tif > *WARNING: Different geotransform matrices found in the set of rasters > being converted to PostGIS raster > *Processing 3/4: srtm_39_01.tif > Processing 4/4: srtm_39_02.tif > > I tried loading the rasters and the roads in qgis, but it didn't manage to > show them together, so I am not sure why its > not aligning. I am sure its some sort of alignment issue, but do not see > where its wrong. I am getting the SRTM files > from http://gis-lab.info/data/srtm-tif/ > And the OSM road was just the map for Denmark on OSM --> > http://download.geofabrik.de/osm/europe/ > > Is it possible for you to intersect these? I understand you are the author > of the postgis tutorial that I am trying to follow > to achieve the same...hence I ask. :) > > Cheers, > Ed > > > > On Mon, Feb 27, 2012 at 2:58 PM, Pierre Racine < > pierre.rac...@sbf.ulaval.ca> wrote: > >> >> >> > -----Original Message----- >> > From: postgis-users-boun...@postgis.refractions.net [mailto: >> postgis-users- >> > boun...@postgis.refractions.net] On Behalf Of Ed Linde >> > Sent: Monday, February 27, 2012 7:21 AM >> > To: postgis-users@postgis.refractions.net >> > Subject: [postgis-users] Raster + Geometry Intersection >> > >> > Hi, >> > I am trying to compute elevations for a road network that I have >> downloaded >> > and installed into my pg database using osm2pgsql. I also have loaded >> SRTM tif >> > files and they are stored as type RASTER in my table. >> > I am now trying to compute an intersection between the SRTM rasters and >> the >> > OSM road geometries... with no luck! :( I am following this tutorial --> >> > http://trac.osgeo.org/postgis/wiki/WKTRasterTutorial01 >> > but I think it might be slightly outdated. >> >> The base queries to do the intersection are still valid. Only the >> uploading changed. And not much. >> >> > SELECT o.osm_id, >> > ST_Intersection(s.rast, o.way) >> > FROM planet_osm_line o, >> > srtm_tiled s >> > WHERE ST_Intersects(s.rast, o.way); >> > >> > way type --> way geometry(LineString,900913) >> > >> > CREATE TABLE public.srtm_tiled >> > ( >> > rid integer NOT NULL DEFAULT nextval('srtm_tiled_rid_seq'::regclass), >> > rast raster, >> > CONSTRAINT srtm_tiled_pkey PRIMARY KEY (rid) >> > ) >> > WITH ( >> > OIDS=FALSE >> > ); >> > >> > performing the above query returns no rows. So I am not sure what is >> wrong.. or >> > if I am doing this query correctly. Is the SRID set differently in the >> raster and >> > geometry? >> >> You should do ST_Intersection(o.way , s.rast) instead of >> ST_Intersection(s.rast, o.way). The first operates in the vector world and >> the second in the raster world. Let me know if that makes a difference in >> terms of results. >> >> Are the SRIDs identical? Did you make sure that the raster were loaded >> properly by displaying values with ST_Value() or ST_DumpAsPolygons() or >> simply displaying the raster in QGIS? Does the raster align with the roads >> properly? >> >> > I also loaded the tif files using the tutorial, but I used the C >> version not the >> > python loader because I understand its been deprecated. >> >> Should not make any difference. >> >> Pierre >> _______________________________________________ >> postgis-users mailing list >> postgis-users@postgis.refractions.net >> http://postgis.refractions.net/mailman/listinfo/postgis-users >> > >
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