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Adapting Motion Capture Data to Follow an Arbitrary Path. Presented by Mark Whitfield. Supervisors: Shaun Bangay and Ad e le Lobb. Problem. Avatar must follow an arbitrary path in a realistic fashion Why use motion capture? Motion capture expensive. Overview. Schools of thought BVH files
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Adapting Motion Capture Data to Follow an Arbitrary Path Presented by Mark Whitfield Supervisors: Shaun Bangay and Adele Lobb
Problem • Avatar must follow an arbitrary path in a realistic fashion • Why use motion capture? • Motion capture expensive
Overview • Schools of thought • BVH files • Motion path editing • Paths • Residuals • Arc-length Reparameterization • Results • Demonstration • Questions
3 Schools of Thought • Alter a base motion • Synthesize a new motion • Cyclic Motions
Motion Path Editing • Altering a base motion • Path is an abstraction of the motion • Motion represented relative to the path • Alter path → alter motion
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
Residuals • Original path (left) • Adapted path (right)
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)
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
Moving Co-Ordinate System • Apply residuals in the moving co-ordinate system
Tangent Vector Projected on Horizontal • Adapted path with motion represented relative to the tangent projected on the horizontal • Original path and motion • Adapted path with motion represented relative to the tangent
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.
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
Shorter and Longer Paths • End of path handling • Cycling
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
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