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Motion Warping. International Conference on Computer Graphics and Interactive Techniques , SIGGRAPH’95 - Andrew Witkin and Zoran Popovi´c. Motion. Set of motion curves each giving model’s parameters as a function of time . Ө. t. Warping.
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Motion Warping International Conference on Computer Graphics and Interactive Techniques, SIGGRAPH’95 -Andrew Witkin and Zoran Popovi´c
Motion • Set of motion curves each giving model’s parameters as a function of time Ө t
Warping • Continuous family of transformations of a graphical object • Transforming Shape • Transforming Attribute
Motion Warping • A technique for editing captured or key framed animation based on warping of the motion parameter curves • Complex motions (Human walk, playing tennis) are radically reshaped with few keyframes
Why Motion Editing?? • Fix Imperfect motions • Reuse motions from Library in multiple settings • Dynamically generate motions for interactive environment
Background • SOFTIMAGETM, ALIASTM, WAVEFRONTTM • Curve Fitting, Global Scaling and Translation (Not suitable for Large scale Transformations) • Data mapping to Image Morphing points (Litwinovicz and Williams [SIGGRAPH ’94]) • Function Fitting [H. Ko and N. I. Badler] • Motion Curve Filtering (M. Unuma and R. Takeuchi) • Multi-resolution Curve Fitting (A. Finkelstein and D. H. Salesin [SIGGRAPH ’94] ) • Blending Techniques (K. Perlin [IEEE Transactions on Visualization and Computer Graphics ])
Signal Deformation • Time warping • Scale and offset Ө Ө’(t) Ө(t) t
Concatenation • Blending Ө Ө2 Ө1 t Өblend Ө2 Ө1
Conclusion • Few motion warping key frames to modify prototype motions • Simple Blending to join overlapping motion clips • Fits well into Familiar keyframe animation paradigm • Limitations • Difficulty in enforcing geometric constraints between keys • Extreme Warps are prone to look distorted and unnatural