Human Figure Modeling and Animation

• Physically based character animation– Human modeled as an articulated body– Ragdoll (for the dead)– Inverse kinematics (for reaching user-specified

goals)

• Data-driven character animation– How to get data?– Motion capture/performance capture– Motion graph (our lab assignment)

Last time…

• Modeling– Skinned model– Features: face and hair

• Activities/Motions– upper body tasks: reaching, grasping– locomotion: walking, running

Virtual Human Representation

Poser Demo

https://www.youtube.com/watch?v=GLhUKaHzzro�

Skinned Human Body

Polygonal representationSkeleton representation

Skinning

Review: Skeleton Model

Joint A

Joint B

Joint C

Bone 1

Bone 2

Joint A

Joint B

Joint C

Bone 1

Bone 2

R1X+b1

R2X+b2

Each bone is doing rigid transformation.

• Let x be a skin vertex in the original space• We can transform x as the combination of the transformations caused by two bones:

w0(R0x+b0) + w1(R1x+b1)

• W0 and w1 are constant weights.• When there are more bones, there are also more weights…• Demo

Skinning/Rigging

https://www.youtube.com/watch?v=PPbSGUPj72w�

Facial animation

Face Modeling

Face animation

Face performance capture

Parameterized Facial features

Also see http://www.facegen.com/

http://www.facegen.com/�

Facial blend shapes

Another (older) example http://www.youtube.com/watch?v=8dS0dcULRBA

Interpolate between 3D models

http://www.youtube.com/watch?v=8dS0dcULRBA�

Real-Time Face Capture

https://www.youtube.com/watch?v=X7y2RZdyZK0�

Hair and fur

Hair

Complexity100,000 strands

Collisions

Shadowing

Reflections

Design hairstyle

Animate hair

Populate head with hair

Hair types

STRANDS AND HAIRMODELING, ANIMATION, AND RENDERING

SIGGRAPH 2007 Course Notes

http://run.usc.edu/cs599-s10/hair/c33-hair-sig07.pdf�http://run.usc.edu/cs599-s10/hair/c33-hair-sig07.pdf�http://run.usc.edu/cs599-s10/hair/c33-hair-sig07.pdf�

• Physically based hair animation– Computationally expensive because of collision– Exact collision handling vs. approximate collision

handling– Simulate a small number of hairs

• The rest hair strands are interpolated– Brave example

Hair Animation and Modeling

https://www.youtube.com/watch?v=Cecx5HVtUDY�

• Data-driven hair animation (with styles!)– Hair capture and modeling from videos

– Manipulating the hair in videos directly!

Hair Animation and Modeling

https://www.youtube.com/watch?v=QCgWMIYGbV8�https://www.youtube.com/watch?v=A14UyhABLJ8�

Capture facial skin and hair together?

The work done by Disney Research

https://www.youtube.com/watch?v=npecw1ohjA8�

Human Body Motion Synthesis

• It is impractical to capture every human motion– Hands (due to occlusions)– Swimming?– Accidents?– Too many motions, cannot capture them all

Human Body Motion Synthesis

https://www.youtube.com/watch?v=G8ge9ir3_Sk�https://www.youtube.com/watch?v=VN7Mb0AM6qo�

• Sometimes the character is non-human

Human Body Motion Synthesis

http://www.disneyresearch.com/project/animating-non-humanoid-characters-with-human-motion-data/�

Human Figure Modeling �and AnimationLast time…Virtual Human Representation幻灯片编号 4幻灯片编号 5幻灯片编号 6Skinning/Rigging幻灯片编号 8幻灯片编号 9幻灯片编号 10幻灯片编号 11Hair and fur幻灯片编号 13Hair Animation and ModelingHair Animation and ModelingCapture facial skin and hair together?Human Body Motion SynthesisHuman Body Motion SynthesisHuman Body Motion Synthesis