v.extrude(1grass) GRASS GIS User's Manual v.extrude(1grass)
NAME
v.extrude - Extrudes flat vector features to 3D vector features with
defined height.
Optionally the height can be derived from sampling of elevation raster
map.
KEYWORDS
vector, geometry, sampling, 3D
SYNOPSIS
v.extrude
v.extrude --help
v.extrude [-t] input=name [layer=string] [cats=range]
[where=sql_query] [type=string[,string,...]] output=name
[zshift=float] [height=float] [height_column=name] [eleva-
tion=name] [method=string] [scale=float] [null_value=float]
[--overwrite] [--help] [--verbose] [--quiet] [--ui]
Flags:
-t
Trace elevation
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog
Parameters:
input=name [required]
Name of input vector map
Or data source for direct OGR access
layer=string
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
cats=range
Category values
Example: 1,3,7-9,13
where=sql_query
WHERE conditions of SQL statement without ’where’ keyword
Example: income < 1000 and population >= 10000
type=string[,string,...]
Input feature type
Options: point, line, area
Default: point,line,area
output=name [required]
Name for output vector map
zshift=float
Shifting value for z coordinates
Default: 0
height=float
Fixed height for 3D vector features
height_column=name
Name of attribute column with feature height
elevation=name
Elevation raster map for height extraction
method=string
Sampling interpolation method
Options: nearest, bilinear, bicubic
Default: nearest
nearest: Nearest-neighbor interpolation
bilinear: Bilinear interpolation
bicubic: Bicubic interpolation
scale=float
Scale factor sampled raster values
Default: 1.0
null_value=float
Height for sampled raster NULL values
DESCRIPTION
v.extrude creates faces, kernels or 3D lines based on input 2D vector
features. Points are converted to 3D vertical lines, lines to faces and
areas to volumes (composition of closed set of faces and kernel).
If elevation parameter is used then 3D vector features follow the ele-
vation model by using individual elevation values for the vertices.
Height for vertices is interpolated from elevation raster map using
given interpolation method.
NOTES
v.extrude extrudes vector features which means that points are con-
verted to vertical lines. Lines and area boundaries are extruded to a
set of faces, each segment defines one face. Area centroids are written
as kernels. Area as a composition of boundaries and centroid is stored
as a closed set of faces and kernel which define a volume.
For conversion of 2D points or lines to 3D can be used v.to.3d or
v.drape. In opposite to v.extrude, these modules do not extrude vector
features, they defines z-coordinate for the features from given parame-
ters or by sampling elevation raster map values. It means that no fea-
ture type conversion is applied, points remain still points in the out-
put vector map. Same applies for the lines.
v.extrude modifies only features geometry. Feature categories remain
untouched and attribute data is copied from input vector map to the
output.
By default, all features (including features without category) from in-
put vector map are processed (layer=-1). Feature selection can be ap-
plied by layer, cats or where parameter.
EXAMPLES
3D houses with fixed height
v.extrude input=houses output=houses3D height=5 type=area
3D houses with individual height
v.extrude input=houses output=houses3D elevation=dem height_column=height type=area
Convert 2D points to 3D vertical lines with fixed height
v.extrude input=geodetic_pts output=points3D height=200 type=point
SEE ALSO
v.transform, v.drape, v.to.3d
wxGUI 3D viewer
AUTHORS
Jachym Cepicky,
Updated for GRASS 7 by Martin Landa, FBK-irst, Italy and Czech Techni-
cal University in Prague, Czech Republic
SOURCE CODE
Available at: v.extrude source code (history)
Accessed: unknown
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GRASS 7.8.7 v.extrude(1grass)
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