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

GRASS GIS trac at osgeo.org
Tue Jan 3 06:20:21 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 pertusus):

 Replying to [comment:10 mmetz]:

 > 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.

 But then, unless I have misunderstood something, the same issue will arise
 for the projection of another vector that crosses the 0/360 border?  Maybe
 this should be discussed in another bug, but when one has vectors all over
 the world and one wants to work with those vectors, it is not possible to
 find a region in which the vectors do not overlap with a boundary.  But I
 may have missed something.

 > 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.

 Unless I missed something this will work if the vector boundary does not
 cross the 0/360 boundary, but will it work in a general case?

 > > 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


Ticket URL: <http://trac.osgeo.org/grass/ticket/1527#comment:11>
GRASS GIS <http://grass.osgeo.org>

More information about the grass-dev mailing list