v.extrudegrass - Online in the Cloud

PROGRAM:

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] [elevation=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 inhab >= 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 elevation 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 converted 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 parameters or by sampling elevation raster map values. It means that
no feature type conversion is applied, points remain still points in the output 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 input vector map are
processed (layer=-1). Feature selection can be applied 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

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