Helper Joints: Advanced Deformations on RunTime Characters

  Game Developers Conference 2005 Session

Helper Joints: Advanced Deformations on RunTime Characters
Speaker: Jason Parks (Technical Artist, Sony Computer Entertainment America)
Time/Date: 12:00-1:00 Firday, March 11th, 2005
Track: Visual Arts
Format: 60-minute Lecture
Experience Level: Advanced - Requires experience and familiarity with subject.
Description: Everybody knows how to make characters look, deform, and move well for rendered cinematic sequences. Things start to get challenging when you are limited to the tools you have available to you at run-time. Luckily there is a way to get all those great deformation tweaks and rigs to work in your game and not just on the screen in your powerful 3D package on your desktop.

There is one simple way to create advanced deformations like muscle bulging, skin-sliding, and general deformation fixes at run-time: extra joints or "helper joints". Because all run-time engines already support joints, it is a relatively small step to optimize your game engine to accommodate the use of a couple or even hundreds of extra helper joints.

This course will review some of the ways to use procedurally-driven extra helper joints to get the deformations you'd really like to see in your game.

Idea Takeaway: The technical artist learns:
* Why an artist would need more joints in their skeleton? Especially those that are not even an approximation to real-life anatomy.
* Where the major problem-areas are in character deformation.
* How an artist should make these extra joints transform.
* What systems an artist can use to drive these extra joints.
* What tools an artist can create to automate the creation of these joints.

Intended Audience and Prerequisites: This course will be most valuable to technical artists who have spent a lot of time painting weights on characters and pulling their hair out trying to find that perfect combination of weights to fix that last vert which just will not behave properly, or anybody who has spent a lot of time making custom blendshapes/morphtargets to fix major binding problems.

[Download Presentation]
This is the presentation only from the GDC website. It contains still images but does NOT contain the 270+ MBs of movies, sorry.

  Research

["Anatomy of Movement” by Blandine C. Germain ]
Anatomy of Movement presents a dynamic, integrated approach to the study of the physical structures of the musculoskeletal system and their functional relationship to the movements of the human body.
[PAN Arts by Warwick Mellow ]
Character setup techniques, with isolated deformations.
["Building Efficient, Accurate Character Skins from Examples" by Mohr/Gleicher]]
Siggraph 2003 paper on auto-computing number and weighting of Helper Joints.


  Playblasts

[SmoothBind]
Standard Smooth Bind of LeftShoulder.




  External Links

Muscle Systems:
[cgMuscle]
Open source muscle plug-in for maya, poly/NURB muscle model in beta, no deformer yet, works great!
[CG|Toolkit: MuscleTK]
Muscle plug-in for Maya with skin simulation, launches November 1rst
[Comet Muscle System]
Muscle plig-in for Maya, hasn't been updated in a while, no beta, looks very promising
[cgCharacter ACT]
Muscle plug-in for 3DS Max, early beta for Maya with no deformer

Pose Deformer Systems:
[Body Blend Reference]
bodyBlend.mel script which automates corrective blendShape creation and animation process.

  Products

[Custom Character Tookit]
Maya Techniques™ | Customer Character Toolkit allows you to explore the methodologies and techniques involved with building a character pipeline.

Updated: 3/16/05