intro

For a long time, i dreamt of creating virtual humans - specifically, a realtime, physical simulation of a human that could interact with its virtual environment.   In 1995-97, i tried to learn sufficient modeling, anatomy and physics for the task.  I gathered lots of notes, wrote some code and attended the virtual humans conference twice.  Eventually, i had to put it on the back burner.

I could describe in great detail why simulated humans haven't happened yet, but that would be too negative, so instead i'll just leave you with my notes, which for the most part haven't been updated since the late 90s.   They do still, however (unfortunately) probably cover the subject more exhaustively than anywhere else on the Web.

notes

• Non-realtime humans are already present in high-end movies and pop culture.
• Likewise, realtime humanoids with fairly well-scripted motion are increasingly common in games, which don't require as much variety of motion.
• I feel the real challenges and rewards are in going beyond scripting to realtime simulation.

• why virtual humans?
• people in this field
• books on this subject
• commercial companies and products
• other organizations and projects
• conferences
• sources of humanoid models
• sources of biometric data
• physical properties
  • need joint ranges and mass, dimensions, moments of inertia.
  • need elastic response curve for each DOF
  • Poser has default joint limits, but they are a "rough guideline" well beyond normal ranges
  • perhaps some information is buried in the biomechanics literature
    • lots of human data resources at Biomechanics World Wide
• realtime simulation
  • Elastic, gravity, and muscle forces
  • Collision - simulation of collision forces - enables the humanoid to stand on its own two feet, and prevent positions which have body parts passing through each other (necessary for accurate grasping and other interaction with worlds objects).
  • Friction - simulation of static and dynamic frictional forces - Nobody has yet attempted this, not even for non-realtime humans! Apparently, one way to approximate friction involves sticking objects together - e.g. feet to ground, hand to tool. This seems like a really crude method. A vaguely accurate approximation should be possible.
  • Dynamic flesh distortion - flesh needs to sag in the direction of gravity and momentum, and distort when collided with - i.e. is needs to be subject to the force simulation engine.
• Higher-level behaviors
  • motion, behavior, AI
• Future
  • bones, muscle, dynamic skin
  • face, lips and tongue
  • other advanced steps
• misc.
  • Distributed environments
    • involving multiple virtual humans, simulated at multiple, separate locations, some of which may be autonomous.
    • Aaron K. Pulkka's thesis on Spatial Culling of Interpersonal Communication within Large-Scale Multi-User Virtual Environments
  • Other Resources
    • There was a thread of discussion on the CGA list about real-time character animation.
    • Jessica Hodgins 'Animating Human Motion' article in March 1998 Scientific American.
    • Stefan Henry-Biskup's 'Anatomically Correct Character Modeling', Game Developer, Nov. 1998
  • finally, peruse some food for thought