[postgis-devel] [PostGIS] #1609: [raster] Implement ST_Merge for ST_Union

PostGIS trac at osgeo.org
Thu Feb 23 07:01:05 PST 2012

#1609: [raster] Implement ST_Merge for ST_Union
 Reporter:  pracine      |       Owner:  pracine      
     Type:  enhancement  |      Status:  new          
 Priority:  medium       |   Milestone:  PostGIS 2.1.0
Component:  raster       |     Version:  trunk        
 Keywords:               |  
 Tentative signature:

 ST_Merge(raster1, band1, raster2, band2, nodataval, pixeltype)

 Merge two rasters together by unioning their extent and burning the last
 raster without taking the other raster pixel values into account. Works on
 multiple bands. The nodata value, when specified, replace the existing
 nodata values. SRIDs must be the same for the two rasters.

 The goal of this function is to be used by ST_union when unioning rasters
 with the 'LAST'  option.

 It could be first easily implemented as a wrapper around ST_MapAlgebra.
 Ideally it should be a C function that we could actually use to optimize
 the two rasters ST_MapAlgebra in certain situations (when extentype is
 INTERSECTION and the expression is 'RAST2' and there is no alternative

Ticket URL: <http://trac.osgeo.org/postgis/ticket/1609>
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