[postgis-tickets] [PostGIS] #2454: [raster] ST_PixelAsPolygons does not obey exclude_nodata_value=TRUE

[PostGIS]

#2454: [raster] ST_PixelAsPolygons does not obey exclude_nodata_value=TRUE
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 Reporter:  alfred  |       Owner:  dustymugs    
     Type:  defect  |      Status:  new          
 Priority:  medium  |   Milestone:  PostGIS 2.1.1
Component:  raster  |     Version:  2.1.x        
 Keywords:          |  
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Comment(by alfred):

 I have been using this workaround for now, by checking if the value is
 equal to the NODATA value.

 In my case i have rasters where only small portions contain data and i am
 attempting to iterate the areas that have data and set values.

 The problem with that is that it increases the query time significantly by
 going over all the pixels (can be thousands of those), even that i care
 only about the ones that have data only.

 I was hoping that now that this function is implemented in C that this
 will provide boost in the speed, which it seems that it does in general,
 but not for this case.

 I still think that having the "exlude_nodata_value" , should NOT return
 those pixels.

 Having it set as false should return all the pixels and the values can
 still be checked with a WHERE clause. I don't see much benefit of having
 it set to NULL as in any case there needs to be a WHERE clause and the
 same can checked for being equal to ST_BandNoDataValue , but may be nice
 option in some cases.

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/2454#comment:7>
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