Virtual Reality and Java 3D - Interactive Web-Based Virtual Reality with Java 3D - page 7

• VRML1.0: This is the earliest version of VRML, and is evolved from SGI's Open

Inventor scene description language. The key feature of this initial standard is a core
set of object oriented constructs augmented by hypermedia links. VRML 1.0 allows
for scene generation by Web browsers on Intel and Apple personal computers as well
as UNIX workstations.

• VRML2.0: This was released in August 96, and expands the specification to address

real time animation on the Web. VRML 2.0 provides local and remote hooks, that is,
an application programming interface or API, to graphical scene description. Dynamic
scene changes are simulated by combinations of scripted actions, message passing,
user commands, and behavior protocols such as Distributed Interaction Simulation
(DIS) or Java.

• VRML97: VRML 2.0 was submitted to ISO (international standards organization)

for publication in May 1997, and redefined as VRML97 by ISO. This became the
industrial standard of non-proprietary file format for displaying scenes consist of
three-dimensional objects on the Web.

• X3D: Currently, VRML (node structure) has evolved or mutated to X3D and much

of it is incorporated into the MPEG-4 standard. X3D can support complex virtual
reality applications. A wider range of interaction techniques and devices is now
supported (Figueroa, Medina, Jimenez, Martýnez, & Albarracýn, 2005; Hudson,
Couch, & Matsuba, 2003; Sommaruga & Catenazzi, 2007,). VRML browsers have
also evolved, and new X3D browsers have been greatly expanded when compared
with the earlier VRML 97 standards with extended media and texture/lighting ca-
pabilities. Technically, X3D is an integration of a new version of VRML using XML
(extensible markup language). Its main disadvantage is that it is not well suited for
constructing complex behaviors (Dachselt & Rukzio, 2003, Mesing & Hellmich,
2006).

3D models under VRML can be created directly and indirectly. Directly, we can use
the descriptive language that VRML provides. The model is then defined in one or more
VRML files, which are regular text files with a standardized syntax. The building blocks of
a VRML model are called VRML nodes, and each node is specified using a standardized
syntax and describes, for example, a three-dimensional shape, a light source, the path for
an animation, the position of a sound source, and so on. The nodes are organized within
what is called a scene graph, which is a hierarchical structure commonly used for building
and managing complex three-dimensional content.
Very often, the virtual objects in VRML can be more easily created using other three-
dimensional modeling software in an indirect manner. As an example, a CAD/CAM system
may be used to create and export objects in the form of VRML nodes that can subsequently
be inserted into a VRML file.