NAME
r.direct - Generates a flow direction map from a
given elevation layer
(GRASS Raster Program)
SYNOPSIS
r.direct
r.direct help
r.direct
input=name
output=name
type=name
DESCRIPTION
r.direct generates a flow direction map from a
given elevation layer.
OPTIONS
Parameters:
- input=name
- elevation map
- output=name
- flow direction map
- type=name
- type of flow direction map to be created.
Options: agnps or grass
The type is the type of format for which the user
wishes to create the flow direction map. The agnps
format gives category values from 1-8, with 1 facing north
and increasing values in the clockwise direction. The
answers format gives category values from 0-360
degrees, with 0 (360) facing east and values increasing in
the counter clockwise direction at 45 degree increments.
The grass format gives the same category values as
the r.slope.aspect
program.
Example
- r.direct input=ansi.elev output=ansi.asp type=grass
will create a flow direction map ansi.asp for the type grass
NOTE
r.direct is sensitive to the current window
setting. Thus the program can be used to generate a
flow direction map for any sub-area within the full map
layer. Also, r.direct is sensitive to any
mask in effect.
SEE ALSO
r.fill.dir
r.slope.aspect
AUTHOR
Raghavan Srinivasan,
Agricultural
Engineering,
Purdue University
Last changed: $Date$