Snap Together Motion : Assembling Run-Time Animation

1. Snap Together Motion : Assembling Run-Time Animation Michael Gleicher Hyun Joon Shin Lucas Kovar Andrew Jepsen University of Wisconsin

2. Virtual Environment • demand on motion synthesis • motion quality • control • little run time overload

3. Virtual Environment • demand on motion synthesis • motion quality • control • little run time overload • snap together motion

4. Basic Idea • processing a corpus of motion data • constructing a highly connected motion graph • making motion segments “snappable”

5. Basic Idea • processing a corpus of motion data • quality • constructing a highly connected motion graph • control • making motion segments “snappable” • little runtime overhead

6. Motion Graph • Kovar et al., Lee et al., and Arikan et al. • constructing graph with edges of pieces of motion • graph searching to synthesize motion • smooth transitions in runtime

7. Motion Graph

8. Overview • structured motion graph with hub nodes • structured graph • hub node: a node with a large number of edges • snappable motion segments • displacement map Original Motion Snappable Motion Hub Node

9. Overview • at run-time • a highly connected graph • concatenating motion pieces at edges … …

10. Authoring • graph construction • choosing match frames • snappable motions • average posture • displacement map • handling constraints

11. Choosing Match Frames • graph construction by user control/heuristic • finding a pose having largest match set • match set: poses with small errors • error metric: point cloud matching [Kovar et al] match set hub error matrix

12. Averaging Poses • coordinate frame alignment • align every match set into a coordinate frame • 2D rigid transformation that minimizes point cloud error point clouds two sequences of poses transformed

13. Averaging Poses • averaging joint angle • use quaternion estimator [Park, Shin, Shin] • orientation with the minimum squared sum of error

14. Displacement Maps • displacement map • fitting average velocities together with pose • two-level displacement map • coarse knots for fitting the pose • denser knots for fitting the velocity

15. Constraints • enforcing consistency in constrained position • problem: • solution: • collecting hub nodes with possible constraint conflicts • determining the constraint position over the set another hub node a hub node a piece with inconsistent constraint

16. Runtime Motion Synthesis • a motion piece • corresponding nodes + coordinate transform • graph traversal • user-controlled traversal • or search algorithm • motion synthesis • concatenating pieces • applying coordinate transformation • little overload

17. Results • Video

18. Summary • a motion synthesis frame work • controllability with highly connected graph • preprocessing everything in authoring step • assembling snappable clips • authoring tool • user-controllable graph construction • seamlessly snappable clips • preserving original motion quality

19. Thanks to

21. Contents • Introduction • Motion Graph • Overview • Choosing Match Frames • Transition • Matching Coordinate Frames • Displacement maps • Constraints • at Run Time

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