[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:  7.4.1
 Component:  Raster       |    Version:  7.0.0
Resolution:               |   Keywords:
       CPU:  Unspecified  |   Platform:  MacOSX
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Comment (by mmetz):

 Replying to [comment:37 hellik]:
 > Replying to [comment:36 hellik]:
 > > Replying to [comment:35 hellik]:
 > > > > {{{
 > > > > 0 black
 > > > > 180 white
 > > > > 360 black
 > > > > }}}
 > > > >
 > > > > should work.
 > > >
 > > > this scheme looks good, see attached
 aspect_nflag_color_color_manual_set.png
 > >
 > > looking at aspect_nflag_color_color_manual_set.png, it seems to be
 just the other way around?

 try

 {{{
 0 white
 180 black
 360 white
 }}}

 IMHO it's a matter of taste if you make north white and south black or
 vice versa.
 >
 > it seems to be more a visual effect as the human eye is used to get an
 illumination in maps of top-left (?)....

 Such an illumination applies to shaded reliefs, see e.g. the azimuth
 option of r.relief.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2637#comment:38>
GRASS GIS <https://grass.osgeo.org>