[postgis-tickets] [PostGIS] #2247: [raster] Create ST_CreateOverviews()

[PostGIS]

#2247: [raster] Create ST_CreateOverviews()
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 Reporter:  dzwarg             |       Owner:  dzwarg       
     Type:  enhancement        |      Status:  new          
 Priority:  medium             |   Milestone:  PostGIS 2.2.0
Component:  raster             |     Version:  trunk        
 Keywords:  raster, overviews  |  
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Comment(by strk):

 So I have the basic version of ST_CreateOverview() working good now.
 It internally loops over every cell of the target tileset and for each
 picks overlapping source tiles, resample them, clip them to target cell,
 snaps to the source grid (to workaround #2920) and finally unions them.

 The function returns a set of rasters, so cannot create constraints
 (raster or overview) because it doesn't deal with creating the table at
 all.

 Now I could split it to have a lower-level companion explicitly taking the
 configuration of the target coverage (origin, scale) and an extent to work
 on. Such a function could be used to parallelize population of the target
 grid from multiple processes/threads.

 At that point the higher-level could also be made into doing more, like
 creating the target table (for which it'd need a name) and all the
 constraints [ as it would not need to scan the target table again to find
 out some of the characteristics ].

 What do you think about the plan ? Ideas about the names of the lower-
 level function (or should it be an overload...) ?

 Current code, as usual, is in the github fork, with a testcase added:
 https://github.com/strk/postgis/tree/svn-trunk-createoverviews

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2247#comment:18>
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