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  geo-
       graphic	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.

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 perfor-
       mance 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 work-
       ing in a lat-lon location are that besides general distor-
       tion  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.



NNOOTTEE
       This is a preliminary release of "p.vrml", a GRASS program
       to output GRASS data in the format of Virtual Reality Mod-
       eling 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 Lab-
       oratory

       _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)
