NAME

       r.out.vrml  - Export 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 elev=string  [color=string]   [exag=float]  output=string  [--verbose]  [--quiet]

   Parameters:
       elev=string
           Name of elevation map

       color=string
           Name of color file

       exag=float
           Vertical exaggeration
           Default: 1.0

       output=string
           Name for new 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 03:29:50 -0800 (Tue, 08 Nov 2011) $

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