VRML for Kinematic and Physical Modeling and Simulations

cuckootrainMechanics

Oct 31, 2013 (3 years and 5 months ago)

74 views

VRML for Kinematic and
Physical Modeling and
Simulations

Benjamin Pugliese

Mahesh Saptharishi

Modeling Requirements


3
-
D representation with object interaction
constraints


Temporal consistency


Real
-
time simulation and visualization of
the model


Combining geometric and non
-
geometric
parameters for simulation (multi
-
modal)

VRML Capabilities


Powerful representations for 3
-
D objects


Temporal event generation


User
-
defined object interaction primitives


Interactive interface


Platform independent


Easily extendible

Applications


High
-
DOF kinematics modeling (
Robot Arm
)


This demonstration exemplifies VRML’s capability
to simulate highly articulated structures. In this
particular example, the combinations of rigid bodies
move independently while being connected. Without
a visualization tool such as VRML it would be very
difficult to imagine the motion of such a machine.

Applications Cont.,


Collision and interference detection (
Kitchen
)


Discrete event simulation involves proper execution of
scheduled temporal events and dynamic events. An
example of a dynamic event is collision detection and
subsequent action. This movie clip demonstrates a
simple collision detection scheme implemented using
VRML. The action induced by the event is the change
in color of the colliding object. The user could define a
whole host of events that could result from this catalyst
event. The kinematics and the analysis for the event
detection was done using JAVA. All visualization and
simulation of the rigid bodies was done with VRML.


Applications Cont.,


Interaction modeling for avatars (
Avatars
)


Another application of VRML is tele
-
presence and
virtual reality worlds. This has been most commonly
used for chat rooms. An application that is slowly
starting to come up is virtual worlds. Virtual worlds
can house shopping complexes, 3D
-
Web pages, etc..

Application Cont.,


Space physics modeling (
NASA
)


NASA has used VRML to model planetary motion,
space shuttle design, and simulation of missions.
The demonstrations in the hyperlink show the ability
of VRML to simulate environmental events such as
temperature, surface winds, light etc. NASA is
primarily interested in VRML because of its ability
to very quickly develop proof
-
of
-
concepts.


Applications Cont.,


Rapid prototyping (
Sojourner
)


NASA used VRML in parts of the MARS mission
planning stage. This demonstration is the National
Geographic Society’s rendition of how the mission
was executed. Design of Sojourner and Pathfinder
and the simulation of its components can also be
seen. Note the power of VRML as an effective
visualization tool. This particular demonstration also
shows the power of multimedia content to design,
develop and demonstrate new ideas.

Disadvantages


Interpreted nature of VRML makes it slow
for display of complicated simulations


Object representations and interaction
primitives can take up a lot of memory


Using VRML for simulation involves a
fairly steep learning curve


No standard interface for extensions

Conclusions


VRML provides a very elegant tool for
simulating and visualizing complex
interactions


It’s popularity is constantly increasing in
the modeling domain


It has the appeal for distributed, internet
based design and modeling

References and Resources


Web 3D Consortium


The VRML Repository


The Annotated VRML Reference Manual


I
-
COLLIDE

Collision detection with
VRML


VRML and the Visualization of Space
Science Data

Answers to questions


Steep learning curve for VRML simulation?
why? better method?


Using VRML, to create simple 3D worlds is very
easy and effective. The complications arise when
trying to program 3D worlds with events to
designate interactions and dynamics in the world.
The event structure, though powerful, is complicated
at first glance. It takes some time to understand how
to use the event architecture in combination with the
VRML reality engine. Other methods such as CAD
have similar problems, but the capabilities of each
differ. VRML is more of a general purpose
simulator while CAD is more application specific.

Answers to questions


How to include kinematics formula into
VRML?


VRML provides for JAVA and C/C++ interfaces for
backend computations. This is necessary because
VRML is largely interpreted and large native
computations slow it down. The
I
-
COLLIDE

package (linked as a reference) is an excellent
example of using JAVA as the computational
backend for VRML
-
based simulation. Please also
see
http://www.igd.fhg.de/CP/scriptgen/

. This web
page provides a java script template generator to
insert within VRML for computations. The VRML
Repository has many other JAVA resources.