[GRASS-dev] [GRASS GIS] #636: r.thin creates triangle at acute intersection of two lines

[GRASS GIS]

#636: r.thin creates triangle at acute intersection of two lines
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 Reporter:  needelsd   |       Owner:  grass-dev at lists.osgeo.org
     Type:  defect     |      Status:  new                      
 Priority:  normal     |   Milestone:  6.4.0                    
Component:  Raster     |     Version:  6.4.0 RCs                
 Keywords:  r.thin     |    Platform:  MacOSX                   
      Cpu:  OSX/Intel  |  
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 I have rasters that were generated using v.rast followed by r.buffer.
 Using r.thin on such a raster occasionally creates a triangle at an
 intersection instead of the expected two intersecting lines. All of the
 examples I have seen involve relatively acute angles (less than 25
 degrees??).

 This result is easily seen by using r.to.vect to create a vector, which
 then needs v.clean to remove dangles. I have attached a screenshot that
 shows the original (fat) raster in magenta, the vector with dangles in
 white, and the cleaned vector as (a thinner) green. There are numerous
 acute angles that generate the vectors I would expect, with one exception
 in the center.

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Ticket URL: <http://trac.osgeo.org/grass/ticket/636>
GRASS GIS <http://grass.osgeo.org>