[GRASS-dev] Re: [GRASS GIS] #1527: vector projection over wrapping boundary is split

GRASS GIS trac at osgeo.org
Tue Jan 3 05:56:39 EST 2012

#1527: vector projection over wrapping boundary is split
  Reporter:  pertusus  |       Owner:  grass-dev@…              
      Type:  defect    |      Status:  reopened                 
  Priority:  normal    |   Milestone:  6.4.2                    
 Component:  Vector    |     Version:  svn-releasebranch64      
Resolution:            |    Keywords:                           
  Platform:  Linux     |         Cpu:  x86-64                   

Comment(by mmetz):

 Replying to [comment:7 pertusus]:
 > A select doesn't cross the boundary. Only the eastern part is selected.
 > I do a grid on the world map and select it by the Lambert map.  I have
 attached a tarball bug_grass_proj_wrap_select.tar.gz to reproduce.  The
 difference between the Lambert map and the selected world map grid may be
 seen by comparing world.png (the Lambert map) and selected.png (the world
 map grid selected).

 Not sure how to handle that. The result of v.select is ok if the grid is
 created on a region with n=90 s=-90 e=360 w=0.

 This would become a problem with e.g. world boundaries wrapped to -180,180
 instead of 0,360. In this case the world boundaries would need to be
 transformed with x shift = 360, the original and transformed world
 boundaries patched and cleaned (preferably also clipped to 0,360) and then
 used as input for v.select together with the Lambert map.
 > The bug_grass_proj_wrap_select.tar.gz also shows the issue mentioned
 above on the missing visible centroids in the world image.  I guess that
 both issues are related.

 I don't think so. The missing centroids are caused by the display

 Markus M

Ticket URL: <http://trac.osgeo.org/grass/ticket/1527#comment:10>
GRASS GIS <http://grass.osgeo.org>

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