[postgis-devel] [PostGIS] #489: [wktraster] ST_PixelSizeY sometimes gives negative answers

[PostGIS]

#489: [wktraster] ST_PixelSizeY sometimes gives negative answers
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  Reporter:  robe       |       Owner:  pracine        
      Type:  defect     |      Status:  new            
  Priority:  medium     |   Milestone:  WKTRaster 0.1.6
 Component:  wktraster  |     Version:  trunk          
Resolution:             |    Keywords:                 
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Comment (by mwtoews):

 Granted I don't know much about wktraster, this seems normal to me since a
 Y-pixel size is a unit vector, not an absolute value. The negative implies
 that that increments in Y-pixels are in the opposite direction to the
 Northings, which is normal since rasters have an origin in the upper-left
 corner and increment downwards while northings increment upwards—therefore
 a negative vector is required.

 This metric in an ESRI World File is typically negative; see line 4:
  * http://en.wikipedia.org/wiki/World_file
  * http://resources.arcgis.com/content/kbase?fa=articleShow&d=17489

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Ticket URL: <http://trac.osgeo.org/postgis/ticket/489#comment:2>
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