[postgis-devel] [PostGIS] #1336: [raster] Problem with ST_MapAlgebraExpr() or ST_AsRaster() alignment

[PostGIS]

#1336: [raster] Problem with ST_MapAlgebraExpr() or ST_AsRaster() alignment
----------------------------+-----------------------------------------------
 Reporter:  pracine         |       Owner:  pracine      
     Type:  defect          |      Status:  new          
 Priority:  medium          |   Milestone:  PostGIS 2.0.0
Component:  postgis raster  |     Version:  trunk        
 Keywords:                  |  
----------------------------+-----------------------------------------------
 I have a test raster that I display in Openjump:

 {{{
 CREATE OR REPLACE FUNCTION ST_TestRaster(h integer, w integer, val float8)
     RETURNS raster AS
     $$
     DECLARE
     BEGIN
         RETURN ST_AddBand(ST_MakeEmptyRaster(h, w, 0, 0, 1, 1, 0, 0, 0),
 '32BF', val, -1);
     END;
     $$
     LANGUAGE 'plpgsql';

 SELECT ST_AsBinary((ST_PixelAsPolygons(ST_TestRaster(10, 10, 2))).geom);
 }}}

 Then I have a simple overlapping geometry:

 {{{
 SELECT ST_AsBinary(ST_Buffer(ST_MakePoint(8, 5), 4));
 }}}

 If I convert it to a raster aligned on the first raster I get:

 {{{
 SELECT ST_AsBinary((gv).geom), (gv).val
 FROM ST_PixelAsPolygons(ST_AsRaster(ST_Buffer(ST_MakePoint(8, 5), 4),
                                     ST_TestRaster(10, 10, 2),
                                     ST_BandPixelType(ST_TestRaster(10, 10,
 2), 1),
                                     1,
                                     -10
                                    )
                         ) gv
 }}}

 The two rasters are well aligned. However if I try:

 {{{
 SELECT ST_MapAlgebraExpr(ST_TestRaster(10, 10, 2), 1,
                          ST_AsRaster(ST_Buffer(ST_MakePoint(8, 5), 4),
                                      ST_TestRaster(10, 10, 2),
                                      ST_BandPixelType(ST_TestRaster(10,
 10, 2), 1),
                                      1,
                                      -10
                                     ), 1,
                          'rast1')
 }}}

 I get "NOTICE:  The two rasters provided do not have the same alignment.
 Returning NULL"...

 If I just replace the rasterized geometry with the original raster like
 this:

 {{{
 SELECT ST_MapAlgebraExpr(ST_TestRaster(10, 10, 2), 1,
                          ST_TestRaster(10, 10, 2), 1,
                          'rast1')
 }}}

 there is no problem...

 I am trying to implement ST_Clip()...

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/1336>
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