## DESCRIPTION

The v.to.3d module is used to transform 2D vector features to 3D. Height (z-coordinate) of 3D vector features can be specified by height parameter as fixed value or by column parameter.

Flag -r enables to perform reverse transformation, i.e., transform 3D vector to 2D by omitting z-coordinate.

## NOTES

When transforming 2D vector features to 3D based on attribute, all NULL values are silently converted to height 0.0.

## EXAMPLES

### Transform 2D vector features to 3D

    # convert z-values from string to double
    v.db.addcol map=geodetic_pts columns="Z_VALUE_D double precision"
    v.db.update map=geodetic_pts column=Z_VALUE_D qcolumn=Z_VALUE
    v.db.select map=geodetic_pts columns=cat,Z_VALUE,Z_VALUE_

    # convert 2D vector point map to 3D based on attribute
    v.to.3d input=geodetic_pts out=geodetic_pts_3d column=Z_VALUE_D

### Transform 3D vector features to 2D

    v.to.3d -rt input=elev_lid792_bepts output=elev_lid_2d

## SEE ALSO

v.transform, v.extrude, v.drape

## AUTHORS

Martin Landa, CTU in Prague, Czech Republic

Last changed: $Date: 2008-12-26 08:48:31 -0800 (Fri, 26 Dec 2008) $