[GRASS-dev] [GRASS GIS] #3468: r.drain: replace with new r.path, support multiple directions

GRASS GIS trac at osgeo.org
Thu Dec 21 01:42:31 PST 2017

#3468: r.drain: replace with new r.path, support multiple directions
  Reporter:  mmetz        |      Owner:  grass-dev@…
      Type:  enhancement  |     Status:  new
  Priority:  normal       |  Milestone:  7.5.0
 Component:  Raster       |    Version:  svn-releasebranch74
Resolution:               |   Keywords:  r.drain
       CPU:  All          |   Platform:  All

Comment (by mmetz):

 Replying to [comment:4 wenzeslaus]:
 > Replying to [comment:3 mmetz]:
 > > That would be a substantial change because other modules (all
 r.stream.*) depend on the direction output of r.watershed.
 > Then I guess we have 3 standards and all make sense. Should all the
 modules have flags, or perhaps an option as r.fill.dir, to set the desired
 direction encoding/format?

 Right now, I have introduced a new -b flag, but that only makes sense if
 there are 2 possible formats. For more different formats, an option as
 r.fill.dir would make sense.

 Instead of changing lots of existing modules, r.path could be enhanced to
 support more different direction formats, e.g. r.watershed's directions.

 > With the naming, I hit an issues with r.path versus r.patch, but I don't
 see any better alternatives. As for the functionality, r.spreadpath now
 comes to my mind, but I don't know right now the relation of backlinks
 there and direction from neighbor and to neighbor.

 If r.spread would produce standard directions instead of x_output,
 y_output with backlink coordinates, r.spreadpath would no longer be needed
 and r.path can be used instead.
 > In r71964 I added an image and extended the example, anybody please


Ticket URL: <https://trac.osgeo.org/grass/ticket/3468#comment:5>
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