p.vrml(1)		      Grass User's Manual		     p.vrml(1)



NNAAMMEE
       pp..vvrrmmll - output of VRML code from GRASS raster maps


       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 major-
       ity of VRML viewers currently only support VRML 1.0.

SSYYNNOOPPSSIISS
       pp..vvrrmmll eelleevv==name [ccoolloorr==name] oouuttppuutt==name

   PPaarraammeetteerrss::
       eelleevv   Name of elevation raster file to use for surface topography.

       ccoolloorr  Name of raster file to use for surface color.

       eexxaagg   Exaggeration factor for the vertical dimension.  Default: 1.0

       oouuttppuutt Name  of	new  VRML file.  If the extension "wrl" (world) is not
	      present in the name, it will be added.


WWAARRNNIINNGG::
       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.



BBUUGGSS::
       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  exag-
       geration  factor (on order of .001) must be used to compensate for ver-
       tical units expected to be the same as map units.



NNOOTTEE
       This is a preliminary release of "p.vrml", a GRASS  program  to	output
       GRASS data in the format of Virtual Reality Modeling Language (VRML).


       For  further  information  about VRML and available viewers for various
       platforms, see:


       http://vag.vrml.org/

       http://www.sdsc.edu/vrml/



TTOODDOO
       Future plans for this module are to allow draping of sites objects  and
       vector files 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.

AAUUTTHHOORR
       Bill Brown, US Army Construction Engineering Research Laboratory

       _L_a_s_t _c_h_a_n_g_e_d_: _$_D_a_t_e_: _2_0_0_2_/_0_1_/_2_5 _0_5_:_4_5_:_3_4 _$



GRASS 5.0							     p.vrml(1)
