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

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Presentation on theme: "Pose Space Deformation: A unified approach to shape interpolation and skeleton-driven deformation J.P.Lewis, Matt Cordner, Nickson Fong Centropolis."— Presentation transcript:

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 1) Body: 1)“skeleton subspace deformation” 2) Face animation: 1)Shape interpolation (Tony de Peltrie, Star Wars, Dinosaur) 2)Custom procedural models (Parke, Toy Story) 3) Common practice for years

3 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 delta shapes: equivalent! (combinations) Shape interpolation (delta)

6 Shape Interpolation Advantages –direct manipulation –desired targets are achieved Disadvantages –Superposition, not independent, linear subspace

7 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 can’t tell when you’re 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

11 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 Addition Interpolation

16 Pose space deformation Left Upper Arm R. Upper Arm Neck Joint Pose Space: N Dimensions Surface CV movement: 3 dimensions Surface cv movement

17 Skeleton driven PSD elbow, f( rotation, load ) face is f( jaw rotation, emotion, phoneme...) quadruped leg/chest/neck

18 Scattered Interpolation Shepard Wiener interpolation, Kriging Others... Radial Basis functions –universal approximation –smooth if smooth kernel –large literature

19 VIDEO: Skeleton driven PSD

20 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 PSD vs. Shape Interpolation (SI)

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

22 Adding smirk counteracts raise Dinosaur: 100+ face shapes Shape Interpolation: reinforcement / fighting raisesmirk +=

23 PSD facial animation Delighted ?Serene Pleased Distressed

24 VIDEO: PSD facial animation Sleepy Aroused PleasureDispleasure J.A.Russell, 1980 (simplified) delighted serene tired frustrated alarmed

25 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: (september)

26

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28 SSD Schematic Robot arm, two cylinders bent at the elbow

29 SSD Schematic

30 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

32 PSD vs. Shape Interpolation SI: adds, not orthogonal, one dimension per shape PSD: interpolates; shapes placed as desired in space

33 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!


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