v.to.rast - Converts (rasterize) a vector map into a raster map.
vector, conversion, raster, rasterization
v.to.rast v.to.rast --help v.to.rast [-d] input=name [layer=string] [type=string[,string,...]] [cats=range] [where=sql_query] output=name use=string [attribute_column=name] [rgb_column=name] [label_column=name] [value=float] [memory=integer] [--overwrite] [--help] [--verbose] [--quiet] [--ui] Flags: -d Create densified lines (default: thin lines) All cells touched by the line will be set, not only those on the render path --overwrite Allow output files to overwrite existing files --help Print usage summary --verbose Verbose module output --quiet Quiet module output --ui Force launching GUI dialog Parameters: input=name [required] Name of input vector map Or data source for direct OGR access layer=string Layer number or name Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name. Default: 1 type=string[,string,...] Input feature type Options: point, line, boundary, area Default: point,line,area cats=range Category values Example: 1,3,7-9,13 where=sql_query WHERE conditions of SQL statement without 'where' keyword Example: income < 1000 and inhab >= 10000 output=name [required] Name for output raster map use=string [required] Source of raster values Options: attr, cat, val, z, dir attr: read values from attribute table cat: use category values val: use value specified by value option z: use z coordinate (points or contours only) dir: output as flow direction (lines only) attribute_column=name Name of column for 'attr' parameter (data type must be numeric) rgb_column=name Name of color definition column (with RRR:GGG:BBB entries) label_column=name Name of column used as raster category labels value=float Raster value (for use=val) Default: 1 memory=integer Maximum memory to be used (in MB) Cache size for raster rows Default: 300
v.to.rast transforms GRASS vector map layers into GRASS raster map layer format. Optionally, attributes can be converted to raster category labels.
In order to avoid unexpected results, the type of vector features should always be specified. The default is to convert all vector features, but if only e.g. areas should be converted use type=area rather than type=point,line,area. v.to.rast will only affect data in areas lying inside the boundaries of the current geographic region. A grid cell belongs to the area where the grid cell center falls into. Before running v.to.rast, the user should therefore ensure that the current geographic region is correctly set and that the region resolution is at the desired level. Either the column parameter or the value parameter must be specified. The use option may be specified alone when using the dir option. use options are: * attr - read values from attribute table (default) * cat - read values from category * val - use value specified by value option * z - use z coordinate (points or contours only) * dir - output as flow direction in degrees (lines only) The column parameter uses an existing column from the vector map database table as the category value in the output raster map. Existing table columns can be shown by using db.describe. An empty raster map layer will be created if the vector map layer has not been assigned category/attribute labels (e.g., through use of v.category option=add). Otherwise: * Labeled areas and/or centroids will produce filled raster coverages with edges that straddle the original area boundary as long as the boundary is NOT labeled. (Use v.category option=del type=boundary to remove.) * Labeled lines and boundaries will produce lines of raster cells which touch the original vector line. This tends to be more aggressive than area-only conversions. * Points and orphaned centroids will be converted into single cells on the resultant raster map. Flow directions are given in degrees counterclockwise from east. Raster category labels are supported for all of use= except use=z. The -d flag applies only to lines and boundaries, the default is to set only those cells on the render path (thin line). Boundaries (usually without categories) can be rasterized with v.to.rast type=boundary layer=-1 use=val
Convert a vector map and use column SPEED from attribute table db.describe -c table=vect_map ncols:3 Column 1: CAT Column 2: SPEED Column 3: WIDTH v.to.rast input=vect_map output=raster_map attribute_column=SPEED type=line Calculate stream directions from a river vector map (Spearfish) v.to.rast input=streams output=streamsdir use=dir Convert a vector polygon map to raster including descriptive labels (Spearfish) v.to.rast input=fields output=myfields use=attr attribute_column=cat label_column=label r.category myfields Convert vector points to raster with raster cell binning In this example, the number of schools per raster cell are counted (North Carolina sample dataset): g.copy vector=schools_wake,myschools_wake # set computation region for raster binning g.region vector=myschools_wake res=5000 -p -a # add new column for counting v.db.addcolumn myschools_wake column="value integer" v.db.update myschools_wake column=value value=1 # verify attributes v.db.select myschools_wake column=cat,value v.out.ascii input=myschools_wake output=- column=value # export and import on the fly, use 4th column (value) as input v.out.ascii input=myschools_wake output=- column=value | r.in.xyz input=- \ z=4 output=schools_wake_aggreg method=sum d.mon wx0 d.rast schools_wake_aggreg d.vect schools_wake d.grid 5000 Number of schools per raster cell
db.describe, v.category
Original code: Michael Shapiro, U.S. Army Construction Engineering Research Laboratory GRASS 6.0 updates: Radim Blazek, ITC-irst, Trento, Italy Stream directions: Jaro Hofierka and Helena Mitasova GRASS 6.3 code cleanup and label support: Brad Douglas Last changed: $Date: 2016-02-22 10:20:45 +0100 (Mon, 22 Feb 2016) $
Available at: v.to.rast source code (history) Main index | Vector index | Topics index | Keywords index | Graphical index | Full index 2003-2016 GRASS Development Team, GRASS GIS 7.2.0 Reference Manual
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