1v.to.rast(1) Grass User's Manual v.to.rast(1)
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6 v.to.rast - Converts (rasterize) a vector map into a raster map.
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9 vector, conversion, raster, rasterization
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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=integer] [--overwrite] [--help] [--verbose]
18 [--quiet] [--ui]
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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
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26 --overwrite
27 Allow output files to overwrite existing files
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29 --help
30 Print usage summary
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32 --verbose
33 Verbose module output
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35 --quiet
36 Quiet module output
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38 --ui
39 Force launching GUI dialog
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41 Parameters:
42 input=name [required]
43 Name of input vector map
44 Or data source for direct OGR access
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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
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53 type=string[,string,...]
54 Input feature type
55 Options: point, line, boundary, area
56 Default: point,line,area
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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
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66 output=name [required]
67 Name for output raster map
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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
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87 value=float
88 Raster value (for use=val)
89 Default: 1
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91 memory=integer
92 Maximum memory to be used (in MB)
93 Cache size for raster rows
94 Default: 300
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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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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.
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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.
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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.
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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.
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118 use options are:
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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)
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128 · dir - line direction in degrees counterclockwise from east
129 (lines only)
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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.
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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).
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139 Otherwise:
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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.)
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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.
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150 · Points and orphaned centroids will be converted into single
151 cells on the resultant raster map.
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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.
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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).
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160 Boundaries (usually without categories) can be rasterized with
161 v.to.rast type=boundary layer=-1 use=val
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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
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172 Calculate stream directions from a river vector map (Spearfish)
173 v.to.rast input=streams output=streamsdir use=dir
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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 (Spearfish)
189 v.to.rast input=fields output=myfields use=attr attribute_column=cat label_column=label
190 r.category myfields
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192 Convert vector points to raster with raster cell binning
193 In this example, the number of schools per raster cell are counted
194 (North Carolina sample dataset):
195 g.copy vector=schools_wake,myschools_wake
196 # set computation region for raster binning
197 g.region vector=myschools_wake res=5000 -p -a
198 # add new column for counting
199 v.db.addcolumn myschools_wake column="value integer"
200 v.db.update myschools_wake column=value value=1
201 # verify attributes
202 v.db.select myschools_wake column=cat,value
203 v.out.ascii input=myschools_wake output=- column=value
204 # export and import on the fly, use 4th column (value) as input
205 v.out.ascii input=myschools_wake output=- column=value | r.in.xyz input=- \
206 z=4 output=schools_wake_aggreg method=sum
207 d.mon wx0
208 d.rast schools_wake_aggreg
209 d.vect schools_wake
210 d.grid 5000
211 Number of schools per raster cell
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214 db.describe, v.category
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217 Original code: Michael Shapiro, U.S. Army Construction Engineering
218 Research Laboratory
219 GRASS 6.0 updates: Radim Blazek, ITC-irst, Trento, Italy
220 Stream directions: Jaro Hofierka and Helena Mitasova
221 GRASS 6.3 code cleanup and label support: Brad Douglas
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223 Last changed: $Date: 2017-03-16 04:03:42 +0100 (Thu, 16 Mar 2017) $
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226 Available at: v.to.rast source code (history)
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228 Main index | Vector index | Topics index | Keywords index | Graphical
229 index | Full index
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231 © 2003-2019 GRASS Development Team, GRASS GIS 7.4.4 Reference Manual
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235GRASS 7.4.4 v.to.rast(1)