[GRASS-dev] [GRASS GIS] #2637: Get direction raster in clockwise degrees starting from the North

[GRASS GIS]

#2637: Get direction raster in clockwise degrees starting from the North
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 Reporter:  cgravelm     |       Owner:  grass-dev@…              
     Type:  enhancement  |      Status:  new                      
 Priority:  normal       |   Milestone:  7.0.1                    
Component:  Raster       |     Version:  7.0.0                    
 Keywords:               |    Platform:  MacOSX                   
      Cpu:  Unspecified  |  
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Comment(by hellik):

 Replying to [ticket:2637 cgravelm]:
 > I have been looking for a way to create a raster direction map using a
 DEM in GRASS (I am currently using the stable 7.0.0 version). So far, the
 3 different scripts that do so (r.param.scale, r.shaded.aspect, and
 r.fill.dir) assume that 0 is at the East and count counterclockwise from
 there. The only way I can create a clockwise direction map with 0 at the
 North is to use the format "agnps" in r.fill.dir. However, this creates a
 map with directions ranging from 0 (equivalent to 0) to 8 (equivalent to
 360 degrees), which can be easily transformed into a 0-360 scale, but
 lacks precision.
 >
 > Would it be possible to add a flag in one of those scripts to create
 maps in degrees that have 0 to the North, 90 to the East and so forth? It
 would make it easier to integrate GRASS rasters to agent-based models.

 have a look e.g. at [http://trac.osgeo.org/grass/browser/grass-
 addons/grass7/raster/r.northerness.easterness/r.northerness.easterness.py#L61
 aspect angles from cartesian (GRASS default) to compass angles] for a
 r.mapcalc calculation

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Ticket URL: <http://trac.osgeo.org/grass/ticket/2637#comment:2>
GRASS GIS <http://grass.osgeo.org>