[postgis-devel] [PostGIS] #985: [raster] ST_Count

PostGIS trac at osgeo.org
Fri May 27 06:57:37 PDT 2011

#985: [raster] ST_Count
  Reporter:  dustymugs       |       Owner:  dustymugs    
      Type:  task            |      Status:  reopened     
  Priority:  medium          |   Milestone:  PostGIS 2.0.0
 Component:  postgis raster  |     Version:  trunk        
Resolution:                  |    Keywords:  history      

Comment(by dustymugs):

 Actually, the information in this ticket's description for hasnodata is
 incorrect.  The correct description for hasnodata should be "If false,
 pixels with nodata values are included in the count".  Pierre explained
 the meaning of hasnodata to me in an email...

 "The doc is correct and consequent with ST_Intersects. If "hasnodata" is
 set to TRUE it means we consider the raster HAS nodata and we take them
 into account. Maybe here is the source of your confusion: Taking nodata
 value into account means IGNORING them (that's really confusing) since
 they are no data. Not taking them into account means "We do like if there
 was NO nodata values" and hence we do not take them into account in the

 There is a difference between a) "Take the nodata value set into account"
 and b) "Take the pixel nodata values into account.

 When a) is TRUE b) is FALSE...

 We are generally speaking about a) in our discussions and this is the
 meaning of the hasnodata parameter.

 Confusing enough?

 If you think of a better way to handle this, let us know."

 I do like "include_nodata" as the argument name is easy to understand in
 the context of the function.

Ticket URL: <https://trac.osgeo.org/postgis/ticket/985#comment:5>
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