Pose Space Deformation:

1
Pose Space Deformation

• A unified approach to shape interpolation and
  skeleton-driven deformation
• J.P.Lewis, Matt Cordner, Nickson Fong
• Centropolis

2
Character animation

• Body
• skeleton subspace deformation
• Face animation
• Shape interpolation (Tony de Peltrie, Star Wars,
  Dinosaur)
• Custom procedural models (Parke, Toy Story)
• Common practice for 10-15 years

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Pose Space Deformation

• Combine direct geometric shape interpolation and
  skeleton driven deformation
• address the limitations of Shape Interpolation
  and Skeleton-driven deformation

4
Shape interpolation

• Blend shapes, multi-target morphs,
• Weighted sum of key shapes
• Or delta shapes...

5
Shape interpolation (delta)

• delta shapes equivalent!
• (combinations)

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Shape Interpolation

• Advantages
• direct manipulation
• desired targets are achieved
• Disadvantages
• Superposition, not independent, linear subspace

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Skeleton Subspace Deformation (SSD)

• enveloping, ...
• Symbolics, Softimage
• Weighted sum of surface point as transformed by
  various coordinate frames.
• Diagram

8
SSD problems collapse
9
SSD problems

• Collapses,
• No direct manipulation,
• You cant tell when youre done

10
Goal

• Combine direct geometric shape interpolation and
  skeleton driven deformation
• BODY use shape interpolation to control shoulder
  shape as it deforms according to the skeleton
• FACE drive the face using jaw rotation rather
  than linear interpolation
• address the limitations of SI, SSD

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Related work

• Combine skeletal and local deformation control
• Burtnyk and Wein, 1976

12
Related work Idea 1

• Animation as scattered interpolation
• Van Overveld, 1990
• Litwinowicz Williams 1994
• Apply wide literature of interpolation directly
  to our animation problem!

13
Related work Idea 2

• Animation, etc. as general functional mapping
• Poggio Brunelli 1992
• Lewis 1988, 91

14
Synthesis

• attempt 1
• Lewis 95 shape interpolation in the context of
  SSD

15
Related work

• Symbolics/Nichimen 91
• Maya

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Pose space deformation
Surface cv movement
Neck Joint
R. Upper Arm
Left Upper Arm
Pose Space N Dimensions
Surface CV movement 3 dimensions
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Skeleton driven PSD

• elbow, f( rotation, load )
• face is f( jaw rotation, emotion, phoneme...)
• quadruped leg/chest/neck

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Scattered Interpolation

• Shepard
• Wiener interpolation, Kriging
• Others...
• Radial Basis functions
• universal approximation
• smooth if smooth kernel
• large literature

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VIDEO Skeleton driven PSD
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PSD vs. Shape Interpolation (SI)

• use same set of sculpted key shapes/delta shapes
• Shape Interpolation is superposition PSD
  interpolates
• SI A B C crossfade is piecewise linear PSD
  is smooth if desired

21
Shape Interpolation vs. PSD

• adds
• one dimension per shape
• not orthogonal
• animator manually solves for the representation

• interpolates
• shapes placed as desired in desired space

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Shape Interpolation reinforcement / fighting

• Adding smirk counteracts raise
• Dinosaur 100 face shapes

raise
smirk
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PSD facial animation
Pleased
Delighted ?
Serene
ltlineargt
Distressed
ltneutralgt
24
VIDEO PSD facial animation
Aroused
J.A.Russell, 1980 (simplified)
alarmed
delighted
frustrated
Pleasure
Displeasure
serene
tired
Sleepy
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Conclusion

• Unification / simplification / modest improvement
  to existing common practice
• How many poses? Like shape interpolation, more is
  better, up to a point...
• Future Learn the space?
• Example code www.idiom.com/zilla/PSD (september)

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SSD Schematic
Robot arm, two cylinders bent at the elbow
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SSD Schematic
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Related work

• Combine skeletal and local deformation control
  (Burtnyk and Wein, 1976)
• Animation as scattered interpolation (Van
  Overveld, 1990 Litwinowicz Williams 1994)
• Animation as general functional mapping (Poggio
  Brunelli 1992 Lewis 1988, 91)
• Lewis 95

31
PSD algorithm steps

• Definitions pose, pose space
• Sculpt
• Define delta(pose)
• Solve
• Synthesize, evaluate, adjust, repeat

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PSD vs. Shape Interpolation
SI adds, not orthogonal, one dimension per shape
PSD interpolates shapes placed as desired in
space
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PSD/SI facial animation

• SI shapes define independent axes, PSD shapes are
  positioned as desired in desired space
• PSD animator plans interpolation path. SI
  animator also has to solve for this path in a
  non-orthogonal basis
• PSD is smooth (if desired)

34
Related Documents

• Marketing plan
• Location or contact name/phone
• Budget
• Location or contact name/phone
• Post mortem
• Location or contact name/phone
• Submit questions
• Location or contact name/phone

35
Project Goals

• Ultimate goal of project
• Relationship to other projects
• High-level timing goals

36
Description

• Describe the project in non-technical terms.
• Use following slides for discussing status,
  schedules, budget, etc.

FOR MORE INFO...
List location or contact for specification (or
other related documents) here
37
Competitive Analysis

• Competitors
• (You may want to allocate one slide per
  competitor)
• Strengths
• Your strengths relative to competitors
• Weaknesses
• Your weaknesses relative to competitor

38
Competitive Analysis, Cont.

• Competitors
• Strengths
• Weaknesses

FOR MORE INFO...
List location or contact for competitive analysis
(or other related documents) here
39
Technology

• New technology being used
• Benefits
• Standards being adopted
• Benefits
• Standards specifically being ignored
• Drawbacks benefits
• DYA define your acronyms!