1r.contour(1)                  Grass User's Manual                 r.contour(1)
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NAME

6       r.contour   -  Produces a vector map layer of specified contours from a
7       raster map layer.
8

KEYWORDS

10       raster
11

SYNOPSIS

13       r.contour
14       r.contour help
15       r.contour  [-qn]  input=name  output=name    [levels=float[,float,...]]
16       [minlevel=float]     [maxlevel=float]     [step=float]    [cut=integer]
17       [--overwrite]  [--verbose]  [--quiet]
18
19   Flags:
20       -q
21           Run quietly
22
23       -n
24           Suppress single crossing error messages
25
26       --overwrite
27           Allow output files to overwrite existing files
28
29       --verbose
30           Verbose module output
31
32       --quiet
33           Quiet module output
34
35   Parameters:
36       input=name
37           Name of input raster map
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39       output=name
40           Name for output vector map
41
42       levels=float[,float,...]
43           List of contour levels
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45       minlevel=float
46           Minimum contour level
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48       maxlevel=float
49           Maximum contour level
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51       step=float
52           Increment between contour levels
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54       cut=integer
55           Minimum number of points for a contour line (0 -> no limit)
56           Default: 0
57

DESCRIPTION

59       r.contour produces a GRASS binary vector map of specified contours from
60       a  GRASS  raster map.  Contours can be produced using a comma-separated
61       list of values in levels, or at some regular increment using  the  step
62       parameter,  using  minlevel and maxlevel as minimum and maximum contour
63       values, respectively. If no minlevel or maxlevel is specified, the min‐
64       imum and maximum cell values in the input raster map will be used.
65

NOTES

67       r.contour will either step through incremental contours or produce con‐
68       tours from a list of levels, not both. If both a list of levels  and  a
69       step  are  specified,  the  list  will be produced and the step will be
70       ignored.
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72       Zero is treated as a valid data value by r.contour.
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74       If a contour level exactly matches a category value in the raster  map,
75       the  contour  line  may backtrack on itself, causing illegal arcs to be
76       produced in the output GRASS vector map.
77
78       The optional cut parameter allows the user to specify a minimum  number
79       of  raster  cells eligilble to be included in a contour line written to
80       the output vector map. It acts like a filter,  omitting  spurs,  single
81       points, etc., making the output more generalized.
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EXAMPLE

84       In  the  Spearfish  location,  produce  a vector contour map from input
85       raster elevation.dem with contour levels from 1000m to 2000m, 100m con‐
86       tour step, and a minimum of 200 input raster points contributing to the
87       contour line: r.contour  input=elevation.dem  output=elevation_dem_con‐
88       tours minlevel=1000 maxlevel=2000 step=100 cut=200
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AUTHORS

91       Terry Baker, U.S. Army Construction Engineering Research Laboratory
92       3/2001: cut parameter and fixes by Andrea Aime (aaime@libero.it)
93
94       Last changed: $Date: 2008-03-14 14:42:11 +0100 (Fri, 14 Mar 2008) $
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96       Full index
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98       © 2003-2008 GRASS Development Team
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102GRASS 6.3.0                                                       r.contour(1)