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Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.

NAME - Performs transformation of 2D vector features to 3D.


vector, geometry, 3D

SYNOPSIS --help [-rt] input=name [layer=string] [type=string[,string,...]] output=name [column=name] [height=float] [--overwrite] [--help] [--verbose] [--quiet] [--ui]


Reverse transformation; 3D vector features to 2D
Do not copy attribute table
Allow output files to overwrite existing files
Print usage summary
Verbose module output
Quiet module output
Force launching GUI dialog


input=name [required]
Name of input vector map
Or data source for direct OGR access
Layer number or name ('-1' for all layers)
A single vector map can be connected to multiple database tables. This number determines which table to use. When used with direct OGR access this is the layer name.
Default: 1
Input feature type
Options: point, line, boundary, centroid
Default: point,line,boundary,centroid
output=name [required]
Name for output vector map
Name of attribute column used for height
Can be used for reverse transformation, to store height of points
Fixed height for 3D vector features

Table of contents


The 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. Height of input 3D features can be optionally stored in column.


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

Reverse transformation is possible for points and lines. In case of lines, the reverse transformation should be used only when all vertices of a line have the same z-coordinate (for example contours).


Transform 2D vector features to 3D

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

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

Transform 3D vector features to 2D -rt input=elev_lid792_bepts output=elev_lid_2d


v.transform, v.extrude, v.drape


Martin Landa, Czech Technical University in Prague, Czech Republic


Available at: source code (history)

Latest change: Thursday Feb 03 11:10:06 2022 in commit: 547ff44e6aecfb4c9cbf6a4717fc14e521bec0be

Note: This document is for an older version of GRASS GIS that will be discontinued soon. You should upgrade, and read the current manual page.

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