[postgis-devel] [PostGIS] #1119: [raster] Modify ST_MapAlgebra so that expressions can refer to any band

[PostGIS]

#1119: [raster] Modify ST_MapAlgebra so that expressions can refer to any band
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 Reporter:  pracine         |       Owner:  pracine              
     Type:  enhancement     |      Status:  new                  
 Priority:  low             |   Milestone:  PostGIS Raster Future
Component:  postgis raster  |     Version:  trunk                
 Keywords:                  |  
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Description changed by pracine:

Old description:

> This could be useful for:
>
> -Writing expressions (like 'average') involving any band of the raster
>
> -Refer to weighted information created by ST_AsRaster() (the length or
> the area of the geometry intersecting with the pixel
>
> In the one raster version of MapAlgebra one could refer to the second
> band like this: 'rast[2]'.
>
> In the two rasters version of MapAlgebra one could refer to the second
> band like this: 'rast1[2] + rast2[2]'.
>
> 'rast', 'rast1' and 'rast2' should by default refer to the value of the
> first band.
>
> This change means that we MUST remove the function's band parameters
> since they are not useful anymore.

New description:

 This could be useful for:

 -Writing expressions (like 'average') involving any band of the raster

 -Refer to weighted information created by ST_AsRaster() (the length or the
 area of the geometry intersecting with the pixel

 In the one raster version of MapAlgebra one could refer to the second band
 like this: 'rast[2]'.

 In the two rasters version of MapAlgebra one could refer to the second
 band like this: 'rast1[2] + rast2[2]'.

 'rast', 'rast1' and 'rast2' should by default refer to the value of the
 first band.

 Out of bound band references should be clamped to the existing band range.

 This change means that we MUST remove the function's band parameters since
 they are not useful anymore.

--

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/1119#comment:3>
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