NAME
r.contour - Produces a GRASS binary vector map of specified
contours from GRASS raster map layer.
(GRASS Raster Program)
SYNOPSIS
r.contour
r.contour help
r.contour [-qn]
input=name
output=name
[levels=value,value,...,value]
[minlevel=value]
[maxlevel=value]
[step=value]
[cut=value]
DESCRIPTION
r.contour produces a contour map of user-specified levels from a
raster map layer. This program works two ways:
-
Contours are produced from a user-specified list of levels.
-
Contours are produced at some regular increment from user-specified minimum
level to maximum level. If no minimum or maximum level is specified, minimum
or maximum data value will be used.
OPTIONS
r.contour may be run interactively or non-interactively. To run
the program non-interactively, the user must specify the input and output
file names, either a list of levels or a step value and, optionally, minimum
and maximum levels:
-
r.contour [-qn] input=name output=name
[levels=value,value,...,value] [minlevel=value]
[maxlevel=value] [step=value]
[cut=value]
To run the program interactively, the user may simply type r.contour
at the command line and will be prompted for parameter values.
Flags:
-q Suppress progress report & min/max information
-n Suppress single crossing error messages
Parameters:
-
input=name
-
Name of input raster map layer.
-
output=name
-
Name of the binary vector file created.
-
levels=value,value,...,value
-
Comma separated list of desired levels.
-
minlevel=value
-
Beginning (lowest) value to be used when stepping through contours. Default
is minimum data value.
-
maxlevel=value
-
Ending (highest) value to be used when stepping through contours. Default
is maximum data value.
-
step=value
-
Increment between contour levels.
-
cut=value
-
Minimum number of points for a contour line (0 -> no limit, default: 0)
NOTES
r.contour will either step through incremental contours or produce
contours from a list of levels, not both. If both a list of levels and
a step are specified, the list will be produced and the step will be ignored.
Zero is treated as a valid data value by r.contour.
If a contour level exactly matches a category value in the raster file,
the contour line may backtrack on itself, causing illegal arcs to be produced
in the output GRASS vector file.
The optional cut parameter allows to specify a minimum number of
point for a contour line to be put into output vector map, so that small
spurs, single points and so on won't be present and the output will be more
clear.
AUTHORS
Terry Baker, U.S. Army Construction Engineering Research Laboratory
3/2001: cut parameter and fixes by Andrea Aime (aaime@libero.it)
Last changed: $Date$