[postgis-users] Raster + Geometry Intersection

[Ed Linde]

I have loaded my SRTM tif files as srid = 4326. And use a ST_Transform on
the road geometry (As suggested).
Running Query:

SELECT o.osm_id,
         ST_Intersection(ST_Transform(o.way,4326), s.rast)
  FROM planet_osm_line o,
       srtm_tiled_4326 s
  WHERE ST_Intersects(ST_Transform(o.way,4326), s.rast);

I get this error:

*NOTICE:  PostGIS was unable to transform the point because either no grid
shift files were found, or the point does
not lie within the range for which the grid shift is defined. Refer to the
ST_Transform() section of the PostGIS manual
for details on how to configure PostGIS to alter this behaviour.

ERROR:  transform: couldn't project point (977705 5.98119e+06 0): failed to
load NAD27-83 correction file (-38)
********** Error **********
ERROR: transform: couldn't project point (977705 5.98119e+06 0): failed to
load NAD27-83 correction file (-38)
SQL state: XX000

*I looked up the postgis manual on ST_Transform and it suggests doing --->

UPDATE spatial_ref_sys SET proj4text = '+proj=longlat +ellps=clrk66
+nadgrids=@conus, at alaska, at ntv2_0.gsb, at ntv1_can.dat,null +no_defs'
WHERE srid = 4326;

Is this the correct way to add a grid? Or is there some better way? Some
other threads on this mailing list suggest copying some files over
and placing them in another folder.. not sure what is the better way. Can
someone please suggest?

I am on -->
-------------------------------------------------------------------------------------------------------------------------------------------------------
* POSTGIS="2.0.0alpha7SVN" GEOS="3.3.0-CAPI-1.7.0" PROJ="Rel. 4.7.1, 23
September 2009" GDAL="GDAL 1.7.3, released 2010/11/10" LIBXML="2.7.8"
USE_STATS
*(1 row)

Cheers,
Ed




On Mon, Feb 27, 2012 at 4:05 PM, Pierre Racine
<Pierre.Racine at sbf.ulaval.ca>wrote:

> > ok, just to get this right.. :) , you are suggesting I keep my OSM as is
> (id: 900913).
> > Load in the tif rasters as srid (4326) and then "reproject" the OSM road
> geometry
> > to srid = 4326 right? So it matches the srid of my raster! I ask because
> you said
> > to reproject to 900913 in your mail.
>
> Correct. We're on the right way.
>
> You can  create a new raster table (after loading them properly with 4326)
> with your rasters reprojected to 900913 but as I said you might hit our bug:
>
> http://trac.osgeo.org/postgis/ticket/1618
>
> Pierre
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>
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