1v.what.rast(1)                Grass User's Manual               v.what.rast(1)
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NAME

6       v.what.rast   -  Uploads raster values at positions of vector points to
7       the table
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KEYWORDS

10       vector, raster, attribute table
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SYNOPSIS

13       v.what.rast
14       v.what.rast help
15       v.what.rast vector=name raster=string  [layer=integer]  column=string
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17   Parameters:
18       vector=name
19           Name of input vector points map for which to edit attribute table
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21       raster=string
22           Name of existing raster map to be queried
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24       layer=integer
25           Layer number Default: 1
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27       column=string
28           Column name (will be updated by raster values)
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DESCRIPTION

31       v.what.rast reads raster value for each point in the vector and updates
32       col  column  in vector attribute table by this value. The column should
33       be type number (integer, float, double, ... ).
34       If more points have the same category, attribute value is set to  NULL.
35       If raster values is NULL, attribute value is set to NULL.
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EXAMPLE

38       A) Reading values from raster map at position of vector points, writing
39       these values into column of vector map:
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41       v.what.rast vect=pnt rast=demf col=valf
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44       B) In case of a vector map without attached attribute table, first  one
45       row  for  each  category has to be generated. Then the new table can be
46       populated with values from the raster map query:
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48       v.db.connect -p vectpoints
49       # .. no table yet.
50       echo 'create table vectpoints (cat integer, value integer)'  |  db.exe‐
51       cute
52       #link new table to vector map:
53       v.db.connect table=vectpoints map=vectpoints
54       #generate rows for each category:
55       v.to.db map=vectpoints option=cat
56       #query raster map and write values into vector table:
57       v.what.rast vect=vectpoints rast=rastmap col=value
58       #verify statistics of uploaded values:
59       v.univar map=vectpoints col=value type=point
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SEE ALSO

63        v.drape, v.what.vect
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AUTHOR

66       Radim Blazek
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68       Last changed: $Date: 2007/03/20 06:24:52 $
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70       Full index
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74GRASS 6.2.2                                                     v.what.rast(1)