1. Adapting Motion Capture Data to Follow an Arbitrary Path Presented by Mark Whitfield Supervisors: Shaun Bangay and Adele Lobb

2. Problem Avatar must follow an arbitrary path in a realistic fashion Why use motion capture? Motion capture expensive

3. Overview Schools of thought BVH files Motion path editing Paths Paths Residuals Residuals Arc-length Reparameterization Arc-length ReparameterizationResultsDemonstrationQuestions

4. 3 Schools of Thought Alter a base motion Synthesize a new motion Cyclic Motions

5. BioVision Hierarchical (BVH) Files

6. Motion Path Editing Altering a base motion Path is an abstraction of the motion Motion represented relative to the path Alter path → alter motion

7. Creating the Initial Path Initial path is created using a least squares fit of the root node translation data InitialPath(t) = point (x(t), y(t), z(t)) x t

8. Residuals Original path (left) Adapted path (right)

9. Residuals Original path and motion (left) Adapted path and motion when residuals represented absolutely (centre) Adapted path and motion when residuals represented relative to the path (right)

10. Moving Co-Ordinate System Y-Up moving co-ordinate system Z axis points in the direction of the tangent projected on the horizontal X axis is their cross product Transform using the residuals in the moving co-ordinate system Then place this co-ordinate system in the world co-ordinate system

11. Moving Co-Ordinate System Apply residuals in the moving co-ordinate system

12. Moving Co-Ordinate System

15. Tangent Vector Projected on Horizontal Original path and motion Adapted path with motion represented relative to the tangent Adapted path with motion represented relative to the tangent projected on the horizontal

16. Arc-Length Reparameterization Altering the path may also alter the speed of the avatar. The arc-length of frame f is the distance along the path from the start of the path to the position on the path at frame f. Frame f in the new path must have the same arc-length as frame f in the original path.

17. Arc-Length Reparameterization Original path on the left Adapted path on the right Not using arc-length reparameterization Original path on the left Adapted path on the right Using arc-length reparameterization

18. Shorter and Longer Paths End of path handling Cycling

19. Results This technique is successful adapting motion capture data to follow an arbitrary path The adapted motion does not look 100% realistic Footskate Constraints were not implemented

20. Future Work Implement constraints Adapt the motion for avatars of different size Multiple avatars which all have paths assigned to them. Implement collision detection and resolution for the avatars

21. DEMONSTRATION