<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>GRASS GIS: v.to.rast</title> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"> <link rel="stylesheet" href="grassdocs.css" type="text/css"> </head> <body bgcolor="white"> <img src="grass_logo.png" alt="GRASS logo"><hr align=center size=6 noshade> <h2>NAME</h2> <em><b>v.to.rast</b></em> - Converts a binary GRASS vector map layer into a GRASS raster map layer. <h2>KEYWORDS</h2> vector, raster, conversion <h2>SYNOPSIS</h2> <b>v.to.rast</b><br> <b>v.to.rast help</b><br> <b>v.to.rast</b> <b>input</b>=<em>name</em> <b>output</b>=<em>name</em> [<b>use</b>=<em>string</em>] [<b>type</b>=<em>string</em>[,<i>string</i>,...]] [<b>layer</b>=<em>integer</em>] [<b>column</b>=<em>name</em>] [<b>value</b>=<em>float</em>] [<b>rows</b>=<em>integer</em>] [<b>rgbcolumn</b>=<em>string</em>] [<b>labelcolumn</b>=<em>string</em>] [--<b>overwrite</b>] [--<b>verbose</b>] [--<b>quiet</b>] <h3>Flags:</h3> <DL> <DT><b>--overwrite</b></DT> <DD>Allow output files to overwrite existing files</DD> <DT><b>--verbose</b></DT> <DD>Verbose module output</DD> <DT><b>--quiet</b></DT> <DD>Quiet module output</DD> </DL> <h3>Parameters:</h3> <DL> <DT><b>input</b>=<em>name</em></DT> <DD>Name of input vector map</DD> <DT><b>output</b>=<em>name</em></DT> <DD>Name for output raster map</DD> <DT><b>use</b>=<em>string</em></DT> <DD>Source of raster values:<br> attr - read values from attribute table<br> cat - use category values<br> val - use value specified by value option<br> z - use z coordinate (points or contours only)<br> dir - output as flow direction (lines only)</DD> <DD>Options: <em>attr,cat,val,z,dir</em></DD> <DD>Default: <em>attr</em></DD> <DT><b>type</b>=<em>string[,<i>string</i>,...]</em></DT> <DD>Type</DD> <DD>Feature type(s)</DD> <DD>Options: <em>point,line,area</em></DD> <DD>Default: <em>point,line,area</em></DD> <DT><b>layer</b>=<em>integer</em></DT> <DD>Layer number</DD> <DD>A single vector map can be connected to multiple database tables. This number determines which table to use.</DD> <DD>Default: <em>1</em></DD> <DT><b>column</b>=<em>name</em></DT> <DD>Name of column for attr parameter (data type must be numeric)</DD> <DT><b>value</b>=<em>float</em></DT> <DD>Raster value</DD> <DD>Default: <em>1</em></DD> <DT><b>rows</b>=<em>integer</em></DT> <DD>Number of rows to hold in memory</DD> <DD>Default: <em>4096</em></DD> <DT><b>rgbcolumn</b>=<em>string</em></DT> <DD>Name of color definition column (with RRR:GGG:BBB entries)</DD> <DT><b>labelcolumn</b>=<em>string</em></DT> <DD>Name of column used as raster category labels</DD> </DL> <h2>DESCRIPTION</h2> <em>v.to.rast</em> transforms GRASS vector map layers into GRASS raster map layer format. Optionally, attributes can be converted into raster category labels. <h2>NOTES</h2> <em>v.to.rast</em> will only affect data in areas lying inside the boundaries of the current geographic region. Before running <em>v.to.rast</em>, the user should therefore ensure that the current geographic region is correctly set and that the region resolution is at the desired level. <P> Either the <em><b>column</b></em> parameter or the <em><b>value</b></em> parameter must be specified. The <em><b>use</b></em> option may be specified alone when using the <em>dir</em> option. <P> <em><b>use</b></em> options are: <ul> <LI> <em>attr</em> - read values from attribute table (default) <LI> <em>cat</em> - read values from category <LI> <em>val</em> - use value specified by <em><b>value</b></em> option <LI> <em>z</em> - use z coordinate (points or contours only) <LI> <em>dir</em> - output as flow direction in degrees (lines only) </ul> <P> The <em><b>column</b></em> 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 <em><a href="db.describe.html">db.describe</a></em>. <P> 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 <a href="v.category.html">v.category option=add</a>). <P> Otherwise: <ul> <LI> Labeled areas and/or centroids will produce filled raster coverages with edges that straddle the original area boundary <b>as long as the boundary is NOT labeled</b>. <BR>(Use <tt>v.category option=del type=boundary</tt> to remove.) <LI> 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. <LI> Points and orphaned centroids will be converted into single cells on the resultant raster map. </ul> <P> <P> <b>Flow directions</b> are given in degrees counterclockwise from east. <P> <P> Raster category labels are supported for all of <em>use=</em> except <em>use=z</em>. <h2>EXAMPLES</h2> <em>1. Convert a vector map and use column SPEED from attribute table</em><br> <div class="code"><pre> db.describe -c table=vect_map ncols:3 Column 1: CAT Column 2: SPEED Column 3: WIDTH </pre></div> <div class="code"><pre> v.to.rast in=vect_map out=raster_map col=SPEED </pre></div> <P> <P> <em>2. Calculate stream directions from a river vector map (Spearfish)</em><br> <div class="code"><pre> v.to.rast in=streams out=streamsdir use=dir </pre></div> </p> <P> <P> <em>3. Convert a vector polygon map to raster including descriptive labels (Spearfish)</em><br> <div class="code"><pre> v.to.rast in=fields out=myfields use=attr col=cat labelcol=label r.category myfields </pre></div> </p> <h2>SEE ALSO</h2> <em> <a HREF="db.describe.html">db.describe</a>, <a HREF="v.category.html">v.category</a> </em> <br> <h2>AUTHORS</h2> Original code: Michael Shapiro, U.S. Army Construction Engineering Research Laboratory <br> GRASS 6.0 updates: Radim Blazek, ITC-irst, Trento, Italy <br> Stream directions: Jaro Hofierka and Helena Mitasova <br> GRASS 6.3 code cleanup and label support: Brad Douglas <p> <p><i>Last changed: $Date: 2008-02-19 21:18:46 +0100 (Tue, 19 Feb 2008) $</i></p> <HR> <P><a href="index.html">Main index</a> - <a href="vector.html">vector index</a> - <a href="full_index.html">Full index</a></P> <P>© 2003-2008 <a href="http://grass.osgeo.org">GRASS Development Team</a></p> </body> </html>
