[GRASS-dev] [GRASS GIS] #1429: r.watershed large grids

[GRASS GIS]

#1429: r.watershed large grids
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 Reporter:  dnewcomb                  |       Owner:  grass-dev@…              
     Type:  enhancement               |      Status:  new                      
 Priority:  normal                    |   Milestone:  7.0.0                    
Component:  Raster                    |     Version:  svn-trunk                
 Keywords:  r.watershed, Large grids  |    Platform:  Linux                    
      Cpu:  x86-64                    |  
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Changes (by neteler):

  * keywords:  Large grids => r.watershed, Large grids
  * component:  Default => Raster


Comment:

 I tried with the current GRASS 7.svn (r59279, approximately 7.0.0beta1)
 and
 r.watershed worked smoothly with 9 billion pixels (77 hours, way more
 pixels
 than in the original report):

 {{{
 GRASS 7.0.svn (nc_spm_08_grass7):~ > g.region rast=elevation -p res=0.15
 projection: 99 (Lambert Conformal Conic)
 zone:       0
 datum:      nad83
 ellipsoid:  a=6378137 es=0.006694380022900787
 north:      228500
 south:      215000
 west:       630000
 east:       645000
 nsres:      0.15
 ewres:      0.15
 rows:       90000
 cols:       100000
 cells:      9000000000

 GRASS 7.0.svn (nc_spm_08_grass7):~ > time -p r.watershed
 elevation=elevation \
   threshold=500000 accumulation=nc_flow_accum_wsh
 drainage=nc_direct_wsh \
   basin=nc_wshed_label_wsh stream=nc_stream_seg_wsh     \
   half_basin=nc_half_basin_wsh memory=42000 -m
 SECTION 1 beginning: Initiating Variables. 5 sections total.
 SECTION 1a: Mark masked and NULL cells
  100%
 SECTION 1b: Determining Offmap Flow.
  100%
 SECTION 2: A* Search.
  100%
 SECTION 3a: Accumulating Surface Flow with MFD.
  100%
 SECTION 3b: Adjusting drainage directions.
 SECTION 4: Watershed determination.
  100%
 SECTION 5: Closing Maps.
 Closing stream segments map
  100%
 Closing basins map
  100%
 Closing half basins map
  100%
 Closing accumulation map
  100%
 Closing flow direction map
 real 277828.64
 user 59672.08
 sys 4481.16

 --> 77.2 hours for

 rows:       90000
 cols:       100000
 cells:      9000000000
 }}}

 Peak memory usage was 10GB (checked with munin).

 Special kudos to Markus Metz for making this possible.

 (I suppose the ticket can be closed at this point)

-- 
Ticket URL: <http://trac.osgeo.org/grass/ticket/1429#comment:2>
GRASS GIS <http://grass.osgeo.org>