[GRASS-dev] [GRASS GIS] #1918: Missing $(RASTERLIB) $(RASTERDEP) in vector/v.in.region/Makefile

[GRASS GIS]

#1918: Missing $(RASTERLIB) $(RASTERDEP) in vector/v.in.region/Makefile
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  Reporter:  torsti  |       Owner:  grass-dev@…              
      Type:  defect  |      Status:  closed                   
  Priority:  normal  |   Milestone:  7.0.0                    
 Component:  Vector  |     Version:  svn-trunk                
Resolution:  fixed   |    Keywords:  v.in.region              
  Platform:  Linux   |         Cpu:  Unspecified              
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Comment(by mmetz):

 Replying to [comment:2 hamish]:
 > from the v.in.region help page:
 >
 >  "If the output of <em>v.in.region</em> is to be used for raster
 > reprojection, the <em>-d</em> flag should be used after setting the
 > region to the raster map to be reprojected with
 > <em><a href="r.proj.html">r.proj</a></em>."
 >
 > It would be good to explain why, and what the flag does to solve it.

 From the r.proj manual:
 "A more involved, but more accurate, way to do this is to generate a
 vector "box" map of the region in the source location using v.in.region.
 This "box" map is then reprojected into the target location with v.proj.
 Next the region in the target location is set to the extent of the new
 vector map with g.region along with the desired raster resolution [...]."

 The extents of the reprojected vector map are often smaller than the
 extents of the reprojected raster map would be, because v.in.region only
 creates points at the box corners. If additional vertices are inserted
 according to the raster resolution, the extents of the reprojected vector
 are different, i.e. larger. In the attached screenshot, the standard
 reprojected vector is in red, the densified vector is in blue. The source
 projection was European LAEA (EPSG:3035), the target projection was
 latlong. The effect of the -d flag for v.in.region is similar to the
 effect of the -p flag for r.proj.

 Markus M

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/1918#comment:3>
GRASS GIS <http://grass.osgeo.org>