p.out.vrml - module to output GRASS data in the format of Virtual Reality Modeling Language (VRML)
p.out.vrml elev=string [color=string] [exag=float] output=string
- Name of elevation file.
- Name of color file.
- Default: 1.0
- Name of new VRML file.
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.
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
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.
This is a preliminary release of "p.out.vrml".
For further information about VRML and available viewers for various platforms, see:
VRML Virtual Reality Modeling Language
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
- Degradation of the raster to produce TINs for improved
Bill Brown, US Army Construction Engineering Research Laboratory
Last changed: $Date: 2005/01/10 17:42:59 $