NAME

       r.out.vrml  - Exports a raster map to the Virtual Reality Modeling Language (VRML).

KEYWORDS

       raster, export, VRML

SYNOPSIS

       r.out.vrml
       r.out.vrml --help
       r.out.vrml elevation=name  [color=name]   [exaggeration=float]  output=name  [--overwrite]
       [--help]  [--verbose]  [--quiet]  [--ui]

   Flags:
       --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:
       elevation=name [required]
           Name of input elevation raster map

       color=name
           Name of input color map

       exaggeration=float
           Vertical exaggeration
           Default: 1.0

       output=name [required]
           Name for output VRML file

DESCRIPTION

       This module exports a GRASS raster map to the Virtual  Reality  Modeling  Language  (VRML)
       format for 3D visualization.

       This  version only outputs raster maps in VRML 1.0 format.  The newer VRML 2.0 format will
       be more efficient for geographic applications, as it introduces an "ElevationGrid" node so
       that only the elevation points will have to be written instead of the whole geometry.  The
       vast majority of VRML viewers currently only support VRML 1.0.   If  the  extension  "wrl"
       (world) is not present in the he output parameter, it will be added.

WARNING

       VRML  is not well suited for large geometrys which can result from even a small geographic
       region.  Most viewers seem to bog down with more than 12,000 polygons, depending  on  your
       hardware  & specific viewer.  Each grid cell results in two polygons, so a reasonable size
       region would be something less than about 75x75.  For  improved  performance  and  smaller
       file  size,  leave  off  a  color  map.  Since VRML is ascii text, gzip works very well to
       significantly compress file size.

NOTE

       This is a preliminary release of "r.out.vrml".  For further  information  about  VRML  and
       available viewers for various platforms, see:

       VRML Virtual Reality Modeling Language

BUGS:

       Currently  the  region is transformed to a unit size, so real geographic location is lost.
       Side effects when working in a lat-lon location are that besides general distortion due to
       projection, a very small exaggeration factor (on order of .001) must be used to compensate
       for vertical units expected to be the same as map units.

TODO

       Update to the more modern GeoVRML format, or  probably  better  the  next  generation  X3D
       format.  See also the Xj3D project.

       Future  plans  for  this  module are to allow draping of sites objects and vector maps and
       using the new sites format available in floating point GRASS to embed WWW links into  site
       objects.  It  will  also  be upgraded to support VRML 2.0 and will allow entering multiple
       preset "views" using the existing GRASS 3d_view file format.

       Other possible additions:

           •   Allow animation of elevation, color, or sites based on user interaction.

           •   Degradation of the raster to produce TINs for improved performance.

AUTHOR

       Bill Brown, US Army Construction Engineering Research Laboratory

       Last changed: $Date: 2011-11-08 22:24:20 +0100 (Tue, 08 Nov 2011) $

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