v.what.rast(1)

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=name   [layer=integer]   column=string
16       [where=sql_query]   [--verbose]  [--quiet]
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18   Parameters:
19       vector=name
20           Name of input vector points map for which to edit attribute table
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22       raster=name
23           Name of existing raster map to be queried
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25       layer=integer
26           Layer number
27           A  single  vector map can be connected to multiple database tables.
28           This number determines which table to use.
29           Default: 1
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31       column=string
32           Column name (will be updated by raster values)
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34       where=sql_query
35           WHERE conditions of SQL statement without 'where' keyword
36           Example: income = 10000
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DESCRIPTION

39       v.what.rast reads raster value for each point in the vector and updates
40       col  column  in vector attribute table by this value. The column should
41       be type number (integer, float, double, ... ).
42       If more points have the same category, attribute value is set to  NULL.
43       If raster values is NULL, attribute value is set to NULL.
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NOTES

46       v.what.rast operates on the attribute table. To modify the vector geom‐
47       etry instead, use v.drape.
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EXAMPLES

50       A) Reading values from raster map at position of vector points, writing
51       these values into column of vector map:
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53       v.what.rast vect=pnts rast=elevation col=heights
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56       B)  In case of a vector map without attached attribute table, first add
57       a new attribute table. This table is then populated with values queried
58       from the raster map:
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60       v.db.connect -p vectpoints
61       # .. no table yet.
62       # add new table, link to map:
63       v.db.addtable  vectpoints  col="cat  integer, myvalue integer, otherval
64       double precision"
65       # query raster map and upload values to  vector  table  into  specified
66       column:
67       v.what.rast vect=vectpoints rast=rastmap col=myvalue
68       # verify new attribute table:
69       v.db.select vectpoints
70       # verify statistics of uploaded values:
71       v.univar map=vectpoints col=myvalue type=point
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AUTHOR

79       Radim Blazek
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81       Last changed: $Date: 2007-06-10 13:23:21 +0200 (Sun, 10 Jun 2007) $
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83       Full index
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85       © 2003-2008 GRASS Development Team
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89GRASS 6.3.0                                                     v.what.rast(1)