[postgis-users] No intersection between two rasters notice

[Francois Hugues]

One more time thank you for the answer Bborie !

Two more details :
1. I didn't know it was possible to use rast::geometry. Is it similar as st_convexhull, st_envelope ?
2. You wrote st_touches != TRUE. Is it the same as ='f'. One is faster than the other ?

Hugues.

 

-----Message d'origine-----
De : postgis-users-bounces at lists.osgeo.org [mailto:postgis-users-bounces at lists.osgeo.org] De la part de Bborie Park
Envoyé : mardi 15 janvier 2013 18:26
À : postgis-users at lists.osgeo.org
Objet : Re: [postgis-users] No intersection between two rasters notice

Yes, part of the issue is due to adjacent tiles.  If you're using PostGIS 2.0, add something like...

AND ST_Touches(rast1::geometry, rast2::geometry) != TRUE

If you're running PostGIS from svn...

AND ST_Touches(rast1, rast2) != TRUE

-bborie

On 01/15/2013 08:45 AM, Francois Hugues wrote:
> Hi everyone,
> 
> I'm facing a new difficulty with rasters. This time with 
> st_MapAlgebraExpr (the whole query is below). I have this notice when 
> I try to cross two rasters with exactly similar tiles.
> NOTICE:  The two rasters provided have no intersection.  Returning no 
> band raster
> 
> To avoid to cross tiles with others where there were effectively no 
> intersection I tried the where clause "where st_intersects(rast1, 
> rast2)" but the problem is not really solved. Is it because of 
> adjacent tiles ?
> 
> Is there a more effective (and faster) way to use mapalgebra and to 
> avoid this creation of empty tiles which prevent to use st_convexhull 
> (and every function which use convexhull) ?
> 
> Hugues.
> 
> select alti.rid, st_mapalgebraexpr(alti.rast, slopes.rast, 
> '[rast1]*[rast2]', '32BF', 'NULL', 'NULL', 'NULL') rast from 
> rasters.alti_cons_ign_alpes alti, rasters.slopes_alpes slopes where 
> st_intersects(alti.rast, slopes.rast)
> 
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> 

--
Bborie Park
Programmer
Center for Vectorborne Diseases
UC Davis
530-752-8380
bkpark at ucdavis.edu
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