1r.to.vect(1) Grass User's Manual r.to.vect(1)
2
6 r.to.vect - Converts a raster map into a vector map layer.
7
9 raster
10
12 r.to.vect
13 r.to.vect help
14 r.to.vect [-svzbq] input=name output=name feature=string [--overwrite]
15 [--verbose] [--quiet]
16 Flags:
18 -s
19 Smooth corners of area features
20 -v
22 Use raster values as categories instead of unique sequence (CELL
23 only)
24 -z
26 Write raster values as z coordinate. Table is not created. Cur‐
27 rently supported only for points.
28 -b
30 Do not build vector topology (use with care for massive point
31 export)
32 -q
34 Quiet - Do not show progress
35 --overwrite
37 Allow output files to overwrite existing files
38 --verbose
40 Verbose module output
41 --quiet
43 Quiet module output
44 Parameters:
46 input=name
47 Name of input raster map
48 output=name
50 Name for output vector map
51 feature=string
53 Feature type
54 Options: point,line,area
55 Default: line
56
58 r.to.vect scans the named input raster map layer, extracts points,
59 lines or area edge features from it, converts data to GRASS vector for‐
60 mat.
61 Points
63 The r.to.vect program extracts data from a GRASS raster map layer and
64 stores output in a new GRASS vector file.
65 Lines
67 r.to.vect assumes that the input map has been thinned using r.thin.
68 r.to.vect extracts vectors (aka, "arcs") from a raster map. These arcs
70 may represent linear features (like roads or streams), or may represent
71 area edge features (like political boundaries, or soil mapping units).
72 r.thin and r.to.vect may create excessive nodes at every junction, and
74 may create small spurs or "dangling lines" during the thinning and vec‐
75 torization process. These excessive nodes and spurs may be removed
76 using v.clean.
77 Areas
79 r.to.vect first traces the perimeter of each unique area in the raster
80 map layer and creates vector data to represent it. The cell category
81 values for the raster map layer will be used to create attribute infor‐
82 mation for the resultant vector area edge data.
83 A true vector tracing of the area edges might appear blocky, since the
85 vectors outline the edges of raster data that are stored in rectangular
86 cells. To produce a better-looking vector map, r.to.vect smoothes the
87 corners of the vector data as they are being extracted. At each change
88 in direction (i.e., each corner), the two midpoints of the corner cell
89 (half the cell's height and width) are taken, and the line segment con‐
90 necting them is used to outline this corner in the resultant vector
91 map. (The cell's cornermost node is ignored.) Because vectors are
92 smoothed by this program, the resulting vector map will not be "true"
93 to the raster map from which it was created. The user should check the
94 resolution of the geographic region (and the original data) to estimate
95 the possible error introduced by smoothing.
96 r.to.vect extracts only area edges from the named raster input file.
98 If the raster map contains other data (i.e., line edges, or point data)
99 the output may be wrong.
100
102 For feature=line the input raster map MUST be thinned by r.thin; if
103 not, r.to.vect may crash.
104
106 Points
107 Bill Brown
108 Lines
109 Mike Baba
110 DBA Systems, Inc.
111 10560 Arrowhead Drive
112 Fairfax, Virginia 22030
113 Areas
114 Original version of r.poly:
115 Jean Ezell and Andrew Heekin,
116 U.S. Army Construction Engineering Research Laboratory
117 Modified program for smoothed lines:
119 David Satnik, Central Washington University
120 Updated 2001 by Andrea Aime, Modena, Italy
121 Update
122 Original r.to.sites, r.line and r.poly merged and updated to 5.7 by
123 Radim Blazek
124 Last changed: $Date: 2007-02-28 16:51:41 +0100 (Wed, 28 Feb 2007) $
126 Full index
128 © 2003-2008 GRASS Development Team
130GRASS 6.3.0 r.to.vect(1)