[postgis-devel] [PostGIS] #593: [raster] Add a ST_BandIsNoData function

[PostGIS]

#593: [raster] Add a ST_BandIsNoData function
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 Reporter:  pracine         |       Owner:  jorgearevalo 
     Type:  task            |      Status:  assigned     
 Priority:  medium          |   Milestone:  PostGIS 2.0.0
Component:  postgis raster  |     Version:  trunk        
 Keywords:                  |  
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Comment(by jorgearevalo):

 Ok, approach used:

 1.- Check if the band is a NODATA band inside the band creation functions
 (rt_band_new_inline, rt_band_from_wkb), and set the flag. [[BR]]

 2.- In rt_band_set_pixel, rt_band_set_nodata reset the flag if needed.

 So, we avoid the out-of-synch situation, and the ST_BandIsNoData function
 only needs to check the flag value.

 Only 2 questions:

 - What should we do in case of offline bands? We could check the values
 using GDAL.[[BR]]

 - Correct me if I'm wrong, but we don't need the isnodata flag to be
 stored in WKB string

 I'll commit the code after testing it (and updating doc)

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/593#comment:5>
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