[GRASS-dev] [GRASS GIS] #2935: r.watershed returns bogus flow direction without warning when using large "virtual" terrain

[GRASS GIS]

#2935: r.watershed returns bogus flow direction without warning when using large
"virtual" terrain
--------------------------+-------------------------
  Reporter:  mankoff      |      Owner:  grass-dev@…
      Type:  defect       |     Status:  new
  Priority:  normal       |  Milestone:  7.0.4
 Component:  Raster       |    Version:  6.4.4
Resolution:               |   Keywords:
       CPU:  Unspecified  |   Platform:  MacOSX
--------------------------+-------------------------
Changes (by mankoff):

 * milestone:   => 7.0.4


Comment:

 I've upgrade to {{{grass 7.0.3}}} and this bug still exists. Here is an
 MWE to recreate it:


 {{{
 grass70 -text ./nc_spm_08_grass7/PERMANENT

 r.rescale input=elev_srtm_30m output=HUGE_elev to=-30000,30000000
 r.rescale input=elev_srtm_30m output=OK_elev to=-30,30000

 r.watershed elevation=HUGE_elev accumulation=HUGE.acc drainage=HUGE.fdir
 r.watershed elevation=OK_elev accumulation=OK.acc drainage=OK.fdir

 g.gui.mapswipe first=HUGE.acc second=OK.acc
 g.gui.mapswipe first=HUGE.fdir second=OK.fdir
 }}}

 Now that grass supports other planets
 https://grasswiki.osgeo.org/wiki/Planetary_mapping it is likely others
 will run into similar issues when flow routing over terrain with values
 significantly larger than Earth topography.

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Ticket URL: <https://trac.osgeo.org/grass/ticket/2935#comment:1>
GRASS GIS <https://grass.osgeo.org>