[postgis-tickets] [PostGIS] #2617: [raster] Enhanced mask object for raster map algebra

[PostGIS]

#2617: [raster] Enhanced mask object for raster map algebra
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 Reporter:  dustymugs    |       Owner:  dustymugs     
     Type:  enhancement  |      Status:  new           
 Priority:  medium       |   Milestone:  PostGIS Future
Component:  raster       |     Version:  trunk         
 Keywords:               |  
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Comment(by nclay):

 This is my thought so far is to introduce a new array in the mask object,
 no-op, it would be used to pad out "Invalid" arrays to "Valid" ones so a
 mask:
 {{{
 mask = [
 1,1,1,1
 1,1,1,1
 1,1,1,1
 ]

 poi = [2,2]
 }}}
 would translate to:
 {{{
 mask = [
 -,-,-,-,-,-,-
 -,-,1,1,1,1,-
 -,-,1,1,1,1,-
 -,-,1,1,1,1,-
 -,-,-,-,-,-,-
 ]
 }}}

 The cells with just a dash in them would be entered in to the no-op array
 as true, thus allowing us to just check the no-op array to see if a read
 is necessary and not write to the returning array. Does anyone have
 objections to this approach or another idea?

 Thanks,

 Nathaniel Hunter Clay

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2617#comment:1>
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