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NAME

r.terracost - Computes a least-cost surface for a given cost grid and set of start points.

KEYWORDS

raster, cost surface, cumulative costs

SYNOPSIS

r.terracost
r.terracost help
r.terracost [-hqisd01234] input=name start_raster=name output=name [numtiles=integer] [memory=integer] [STREAM_DIR=string] [VTMPDIR=string] [tileStr=string] [bndStr=string] [bspStr=string] [sbspStr=string] [config=string] [phase2Bnd=string] [stats=string] [tilesAreSorted=string] [--overwrite] [--verbose] [--quiet]

Flags:

-h
Help
-q
Quiet
-i
Info (print suggested numtiles information and exit)
-s
Dbg: Save output to ASCII file "DIST_GRID"
-d
Dbg: Print (a lot of) debug info (developer use)
-0
Dbg: Step 0 only (default: run all)
-1
Dbg: Step 1 only (default: run all)
-2
Dbg: Step 2 only (default: run all)
-3
Dbg: Step 3 only (default: run all)
-4
Dbg: Step 4 only (default: run all)
--overwrite
Allow output files to overwrite existing files
--verbose
Verbose module output
--quiet
Quiet module output

Parameters:

input=name
Name of raster map containing grid cell cost information
start_raster=name
Name of starting raster points map
output=name
Output distance grid raster map
numtiles=integer
Number of tiles (default: 1)
Default: 1
memory=integer
Main memory size (in MB)
Default: 400
STREAM_DIR=string
Location of temporary STREAMs
Default: /var/tmp
VTMPDIR=string
Location of intermediate STREAMs
Default: /var/tmp/martinl
tileStr=string
Dbg: Stream name stem for step 0 output
Default: terracost.tileStr
bndStr=string
Dbg: Stream name for boundary data structure
Default: terracost.bndStr
bspStr=string
Dbg: Output file for step 1
Default: terracost.bspStr
sbspStr=string
Dbg: Output file for source to boundary stream
Default: terracost.sbspStr
config=string
Dbg: Name for config file
Default: terracost.config
phase2Bnd=string
Dbg: Name for phase2Bnd file
Default: terracost.phase2Bnd
stats=string
Dbg: Stats file
Default: terracost.stats
tilesAreSorted=string
Dbg: Tiles are sorted (used in grid version) (y/n)
Default: no

DESCRIPTION

r.terracost is a scalable approach for computing least-cost-path surfaces on massive grid terrains. The module outperforms standard solutions as dataset size increases relative to available memory.

NOTES

r.terracost computes a least-cost surface for a given cost grid and set of start points using an approach that scales to large grids. For details, see paper "TerraCost: A Versatile and Scalable Approach for Path Computations on Massive Grid-Based Terrains" by Hazel, Toma, Vahrenhold and Wickremesinghe (2006). The basic idea is to split the grid in tiles. numtiles is the number of tiles. Run with -i to see the recommended value for numtiles. When numtiles=1 it runs Dijkstra's algorithm in memory. When numtiles > 1 it runs an external SP algorithm that consists of 5 steps. For debugging purposes, it is possible to run the five steps separately. When running in separate steps, an intermediate config file stores temporary information, and other streams (see below) contain intermediate data. IOLibrary temporary streams will be in STREAM_DIR.

REFERENCES

SEE ALSO

r.cost, r.drain, r.walk

AUTHOR

Laura I. Toma, http://www.bowdoin.edu/~ltoma/research.html

Last changed: $Date: 2010-10-09 21:13:35 -0700 (Sat, 09 Oct 2010) $


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