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       v.what.rast3  - Uploads 3D raster values at positions of vector points to the table.


       vector, sampling, raster, position, querying, attribute table, surface information


       v.what.rast3 --help
       v.what.rast3   map=name   [layer=string]   raster_3d=name  column=name   [where=sql_query]
       [--help]  [--verbose]  [--quiet]  [--ui]

           Print usage summary

           Verbose module output

           Quiet module output

           Force launching GUI dialog

       map=name [required]
           Name of vector points map for which to edit attributes
           Or data source for direct OGR access

           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

       raster_3d=name [required]
           Name of existing 3D raster map to be queried

       column=name [required]
           Name of attribute column to be updated with the query result

           WHERE conditions of SQL statement without ’where’ keyword
           Example: income < 1000 and population >= 10000


       v.what.rast3  reads 3D raster value for each point in the vector and updates col column in
       vector attribute table by this value. The column should be type  double.  This  module  is
       based on v.what.rast.
       If  more  points  have  the  same  category, attribute value is set to NULL.  If 3D raster
       values is NULL, attribute value is set to NULL.



       A) Reading values from 3D raster map at position of vector points,  writing  these  values
       into a column of the attribute table connected to the vector map:
       v.what.rast3 map=pnts raster3d=plume column=concentration

       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:
       # create new random 3d vector points map
       v.random -z output=pnts npoints=100 zmin=0  zmax=50
       # add new table, link to map
       v.db.addtable map=pnts column="concentration double precision"
       # query raster map and upload values to vector table into specified column
       g.region raster3d=plume -p
       v.what.rast3 map=pnts raster3d=plume column=concentration
       # verify new attribute table: map=pnts
       # verify statistics of uploaded values:
       v.univar map=pnts column=concentration type=point


        v.db.addtable,, v.what.rast, v.what.vect, v.univar


       Soeren Gebbert, heavily based on v.what.rast by Radim Blazek

       Last changed: $Date: 2018-06-12 00:50:44 +0200 (Tue, 12 Jun 2018) $


       Available at: v.what.rast3 source code (history)

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