
\section{Virtual Reality Modeling Language (VRML)}

\begin{slide}
\subsection{\bf What is VRML?} 

Virtual Reality Modeling Language (VRML) is a format for specifying
3D virtual worlds that can be downloaded over the Web and displayed 
using VRML browsers. 

The initial language specification and browsers were
based on Silicon Graphics' Open Inventor, a platform-independent
toolkit and modeling system for 3D graphics applications. 

The data is downloaded to the client, which does the rendering, and allows
the user to interactively move through the virtual world. 
In version 1 of VRML, the world is static -- only the user's
viewpoint changes. VRML 2.0 will allow dynamic worlds.

\end{slide}


\begin{slide}
\subsection{\bf Object Specification in VRML} 

The 3D objects are defined using polygons or standard shapes such
as cubes and spheres, with colors or texture maps associated with each
polygon or shape. 


\begin{slide}
\subsection{\bf Terrain Models in VRML} 

A terrain model in VRML is defined as a set of polygons, which can be
texture mapped. 
VRML 1.1 includes a special format for terrain, called an elevation grid.

To save rendering time, VRML allows the scene to be defined so that 
objects at a distance are rendered at lower resolution, which is 
necessary for adequate frame rates in terrain rendering.

VRML also allows the data set for the virtual world to be downloaded a
section at a time, which is necessary for interactive flights over large 
areas, where the whole data set can take up Gigabytes.

\end{slide}

