[postgis-tickets] [PostGIS] #2281: multiband raster burning (braindump)

[PostGIS]

#2281: multiband raster burning (braindump)
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 Reporter:  strk         |       Owner:  dustymugs     
     Type:  enhancement  |      Status:  new           
 Priority:  medium       |   Milestone:  PostGIS Future
Component:  raster       |     Version:  trunk         
 Keywords:               |  
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Comment(by pracine):

 1) There is already a variant of ST_AsRaster() that takes many values and
 produce a multiple band raster.

 2) To aggregate many geometries values into a single band you must use the
 right multiband variant of ST_Union(). You normally use 'LAST" or 'MEAN'
 to determine the value of  overlapping pixels.

 3) To aggregation multiple band together it's ST_Union again with the
 'MEAN' or 'COUNT' argument.

 ST_UnionToRaster will only be a wrapper around ST_AsRaster() and
 ST_Union(). So the combination of 1) and 2)...

 Does this fullfill your needs?

 Another way is to use ST_MapAlgegra with a custom function that would do a
 query on the vector coverage for every pixel of a pre georeferenced
 raster. That is way more flexible, but a bit slower (my guess is that this
 is still faster than ST_Union for huge rasters). See my blog.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2281#comment:2>
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