1v.to.rast(1)                GRASS GIS User's Manual               v.to.rast(1)
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NAME

6       v.to.rast  - Converts (rasterize) a vector map into a raster map.
7

KEYWORDS

9       vector, conversion, raster, rasterization
10

SYNOPSIS

12       v.to.rast
13       v.to.rast --help
14       v.to.rast  [-d] input=name  [layer=string]   [type=string[,string,...]]
15       [cats=range]        [where=sql_query]       output=name      use=string
16       [attribute_column=name]      [rgb_column=name]      [label_column=name]
17       [value=float]    [memory=memory  in   MB]     [--overwrite]    [--help]
18       [--verbose]  [--quiet]  [--ui]
19
20   Flags:
21       -d
22           Create densified lines (default: thin lines)
23           All  cells  touched  by the line will be set, not only those on the
24           render path
25
26       --overwrite
27           Allow output files to overwrite existing files
28
29       --help
30           Print usage summary
31
32       --verbose
33           Verbose module output
34
35       --quiet
36           Quiet module output
37
38       --ui
39           Force launching GUI dialog
40
41   Parameters:
42       input=name [required]
43           Name of input vector map
44           Or data source for direct OGR access
45
46       layer=string
47           Layer number or name
48           Vector features can have category values in different layers.  This
49           number  determines  which  layer  to use. When used with direct OGR
50           access this is the layer name.
51           Default: 1
52
53       type=string[,string,...]
54           Input feature type
55           Options: point, line, boundary, centroid, area
56           Default: point,line,area
57
58       cats=range
59           Category values
60           Example: 1,3,7-9,13
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62       where=sql_query
63           WHERE conditions of SQL statement without ’where’ keyword
64           Example: income < 1000 and population >= 10000
65
66       output=name [required]
67           Name for output raster map
68
69       use=string [required]
70           Source of raster values
71           Options: attr, cat, val, z, dir
72           attr: read values from attribute table
73           cat: use category values
74           val: use value specified by value option
75           z: use z coordinate (points or contours only)
76           dir: line direction in degrees CCW from east (lines only)
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78       attribute_column=name
79           Name of column for ’attr’ parameter (data type must be numeric)
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81       rgb_column=name
82           Name of color definition column (with RRR:GGG:BBB entries)
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84       label_column=name
85           Name of column used as raster category labels
86
87       value=float
88           Raster value (for use=val)
89           Default: 1
90
91       memory=memory in MB
92           Maximum memory to be used (in MB)
93           Cache size for raster rows
94           Default: 300
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DESCRIPTION

97       v.to.rast transforms GRASS vector map  layers  into  GRASS  raster  map
98       layer  format.  Optionally, attributes can be converted to raster cate‐
99       gory labels.
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NOTES

102       In order to avoid unexpected  results,  the  type  of  vector  features
103       should  always  be specified. The default is to convert all vector fea‐
104       tures, but if only e.g. areas should be converted use type=area  rather
105       than type=point,line,area.
106
107       v.to.rast will only affect data in areas lying inside the boundaries of
108       the current geographic region.  A grid cell belongs to the  area  where
109       the grid cell center falls into.
110
111       Before  running  v.to.rast,  the  user should therefore ensure that the
112       current geographic region is correctly set and that the region  resolu‐
113       tion is at the desired level.
114
115       Either  the  column parameter or the value parameter must be specified.
116       The use option may be specified alone when using the dir option.
117
118       use options are:
119
120           ·   attr - read values from attribute table (default)
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122           ·   cat  - read values from category
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124           ·   val  - use value specified by value option
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126           ·   z    - use z coordinate (points or contours only)
127
128           ·   dir  - line direction in  degrees  counterclockwise  from  east
129               (lines only)
130
131       The  column parameter uses an existing column from the vector map data‐
132       base table as the category value in the output raster map. Existing ta‐
133       ble columns can be shown by using db.describe.
134
135       An  empty  raster map layer will be created if the vector map layer has
136       not been assigned  category/attribute  labels  (e.g.,  through  use  of
137       v.category option=add).
138
139       Otherwise:
140
141           ·   Labeled  areas and/or centroids will produce filled raster cov‐
142               erages with edges that straddle the original area  boundary  as
143               long as the boundary is NOT labeled.
144               (Use v.category option=del type=boundary to remove.)
145
146           ·   Labeled lines and boundaries will produce lines of raster cells
147               which touch the original vector line. This  tends  to  be  more
148               aggressive than area-only conversions.
149
150           ·   Points  and  orphaned  centroids  will be converted into single
151               cells on the resultant raster map.
152
153       Line directions are given in degrees counterclockwise from east.
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155       Raster category labels are supported for all of use= except use=z.
156
157       The -d flag applies only to lines and boundaries, the default is to set
158       only those cells on the render path (thin line).
159
160       Boundaries (usually without categories) can be rasterized with
161       v.to.rast type=boundary layer=-1 use=val
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EXAMPLES

164   Convert a vector map and use column SPEED from attribute table
165       db.describe -c table=vect_map
166       ncols:3
167       Column 1: CAT
168       Column 2: SPEED
169       Column 3: WIDTH
170       v.to.rast input=vect_map output=raster_map attribute_column=SPEED type=line
171
172   Calculate stream directions from a river vector map (Spearfish)
173       v.to.rast input=streams output=streamsdir use=dir
174
175   Calculate slope along path
176       Using  slope and aspect maps, compute slope along a bus route (use full
177       NC sample dataset):
178       g.region raster=elevation -p
179       r.slope.aspect elevation=elevation slope=slope aspect=aspect
180       # compute direction of the bus route
181       v.to.rast input=busroute11 type=line output=busroute11_dir use=dir
182       # extract steepest slope values and transform them into slope along path
183       r.mapcalc "route_slope = if(busroute11, slope)"
184       r.mapcalc "route_slope_dir = abs(atan(tan(slope) * cos(aspect - busroute11_dir)))"
185       Slope in degrees along bus route
186
187   Convert a vector polygon map to raster including descriptive labels
188       In this example, the ZIP code vector map is rasterized (North  Carolina
189       sample dataset):
190       # rasterize ZIP codes at 50m raster resolution
191       g.region vector=zipcodes_wake res=50 -ap
192       # vector to raster conversion, with category labels
193       v.to.rast input=zipcodes_wake output=myzipcodes use=attr attribute_column="ZIPNUM" label_column="NAME"
194
195   Convert vector points to raster with raster cell binning
196       In  this  example,  the  number  of schools per raster cell are counted
197       (North Carolina sample dataset):
198       g.copy vector=schools_wake,myschools_wake
199       # set computation region for raster binning
200       g.region vector=myschools_wake res=5000 -p -a
201       # add new column for counting
202       v.db.addcolumn myschools_wake column="value integer"
203       v.db.update myschools_wake column=value value=1
204       # verify attributes
205       v.db.select myschools_wake column=cat,value
206       v.out.ascii input=myschools_wake output=- column=value
207       # export and import on the fly, use 4th column (value) as input
208       v.out.ascii input=myschools_wake output=- column=value | r.in.xyz input=- \
209                   z=4 output=schools_wake_aggreg method=sum
210       d.mon wx0
211       d.rast schools_wake_aggreg
212       d.vect schools_wake
213       d.grid 5000
214       Number of schools per raster cell
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SEE ALSO

217        db.describe, v.category
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AUTHORS

220       Original code: Michael  Shapiro,  U.S.  Army  Construction  Engineering
221       Research Laboratory
222       GRASS 6.0 updates: Radim Blazek, ITC-irst, Trento, Italy
223       Stream directions: Jaro Hofierka and Helena Mitasova
224       GRASS 6.3 code cleanup and label support: Brad Douglas
225

SOURCE CODE

227       Available at: v.to.rast source code (history)
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229       Main  index  | Vector index | Topics index | Keywords index | Graphical
230       index | Full index
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232       © 2003-2020 GRASS Development Team, GRASS GIS 7.8.5 Reference Manual
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236GRASS 7.8.5                                                       v.to.rast(1)
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