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v.what.rast.1grass
Langue: en
Version: 336287 (ubuntu - 24/10/10)
Section: 1 (Commandes utilisateur)
NAME
v.what.rast - Uploads raster values at positions of vector points to the table.KEYWORDS
vector, raster, attribute tableSYNOPSIS
v.what.rastv.what.rast help
v.what.rast vector=name raster=name [layer=integer] column=string [where=sql_query] [--verbose] [--quiet]
Parameters:
- vector=name
Name of input vector points map for which to edit attribute table- raster=name
Name of existing raster map to be queried- layer=integer
Layer number
A single vector map can be connected to multiple database tables. This number determines which table to use.
Default: 1- column=string
Column name (will be updated by raster values)- where=sql_query
WHERE conditions of SQL statement without 'where' keyword
Example: income = 10000
DESCRIPTION
v.what.rast reads raster value for each point in the vector and updates col column in vector attribute table by this value. The column should be type number (integer, float, double, ... ).If more points have the same category, attribute value is set to NULL. If raster values is NULL, attribute value is set to NULL.
NOTES
v.what.rast operates on the attribute table. To modify the vector geometry instead, use v.drape.EXAMPLES
A) Reading values from raster map at position of vector points, writing these values into column of vector map:v.what.rast vect=pnts rast=elevation col=heights
B) In case of a vector map without attached attribute table, first add a new attribute table. This table is then populated with values queried from the raster map:
v.db.connect -p vectpoints
# .. no table yet.
# add new table, link to map:
v.db.addtable vectpoints col="cat integer, myvalue integer, otherval double precision"
# query raster map and upload values to vector table into specified column:
v.what.rast vect=vectpoints rast=rastmap col=myvalue
# verify new attribute table:
v.db.select vectpoints
# verify statistics of uploaded values:
v.univar map=vectpoints col=myvalue type=point
SEE ALSO
v.db.addtable, v.db.select, v.drape, v.univar, v.rast.stats, v.what.vectAUTHOR
Radim BlazekLast changed: $Date: 2007-06-10 13:23:21 +0200 (dom, 10 giu 2007) $
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