VRML for Kinematic and Physical Modeling and Simulations

1
VRML for Kinematic and Physical Modeling and
Simulations

• Benjamin Pugliese
• Mahesh Saptharishi

2
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)

3
VRML Capabilities

• Powerful representations for 3-D objects
• Temporal event generation
• User-defined object interaction primitives
• Interactive interface
• Platform independent
• Easily extendible

4
Applications

• High-DOF kinematics modeling (Robot Arm)
• This demonstration exemplifies VRMLs 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.

5
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.

6
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..

7
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.

8
Applications Cont.,

• Rapid prototyping (Sojourner)
• NASA used VRML in parts of the MARS mission
  planning stage. This demonstration is the
  National Geographic Societys 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.

9
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

10
Conclusions

• VRML provides a very elegant tool for simulating
  and visualizing complex interactions
• Its popularity is constantly increasing in the
  modeling domain
• It has the appeal for distributed, internet based
  design and modeling

11
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

12
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.

13
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.