[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):

 Replying to [comment:6 pracine]:
 > > - What should we do in case of offline bands? We could check the
 values using GDAL.[[BR]]
 >
 > This job should be done by raster2pgsql.py
 >

 OK

 > > - Correct me if I'm wrong, but we don't need the isnodata flag to be
 stored in WKB string
 >
 > Yes. It must be persistent. The code should look exactly like the code
 for hasnodata.
 >

 Ok. We still have 2 unused bits per band.

 > Most of the work has to be done in raster2pgsql.py (and every set pixel
 functions).

 In rt_band_set_pixel the flag is reset if the pixel is different from
 nodata. And in rt_band_set_nodata, we must check if the new nodata value
 matchs the rest of the pixels.

 These are the 2 entries for storing new raster data. In raster2pgsql.py we
 must set the flag when dealing with offdb bands. The rest of the cases are
 managed by the 2 core functions mentioned (rt_band_set_pixel,
 rt_band_set_nodata).

 Am I missing something?

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/593#comment:9>
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