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 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 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

SEE ALSO

        v.transform, v.extrude, v.drape, v.to.3d

        wxGUI 3D viewer

AUTHORS

       Jachym Cepicky,
       Updated  for  GRASS  7  by Martin Landa, FBK-irst, Italy and Czech Technical University in
       Prague, Czech Republic

       Last changed: $Date: 2014-11-28 17:22:17 +0100 (Fri, 28 Nov 2014) $

SOURCE CODE

       Available at: v.extrude source code (history)

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       © 2003-2018 GRASS Development Team, GRASS GIS 7.4.0 Reference Manual