Multi-Character Animation using Motion Capture Data

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Efficient computation of strategic movements is essential to control virtual characters intelligently in computer games and 3D virtual environments. Manually creating the motions of avatars is time consuming due to the correlation of the movements between the avatars. Capturing the motions of multiple avatars is also difficult as it requires a huge amount of post-processing. We propose a series of methods for generating a realistic animation of virtual characters densely interacting in a competitive or cooperative environment. We use the MoCap data of a single actor/actress as an input, and synthesize character animations using an action-level motion graph. The interaction between characters are automatically generated by expanding and searching the motion graphs using a min-max optimization. A long animation sequence can be generated efficiently by pre-computing pair-wise interactions, since the subspace of meaningful interactions is much smaller than the whole state space of two characters. At run time, the system spatio-temporally concatenates the pre-computed interactions to create scenes where a large number of characters closely interact with one another.

Publications

Hubert Shum, Taku Komura, Masashi Shiraish, and Shuntaro Yamazaki,
Interaction Patches for Multi-Character Animation ”,
ACM Transactions on Graphics, 27(5), pp.114:1-114:8,
December 2008
[Paper ] [Movie ] [Presentation ] [BibTex ]

Hubert Shum, Taku Komura, and Shuntaro Yamazaki,
Simulating Interactions of Avatars in High Dimensional State Space ”,
Proc. ACM Symposium on Interactive 3D Graphics and Games, pp.131-138,
January 2008.
[Paper ] [Movie ] [Presentation ] [BibTex ]

Hubert Shum, Taku Komura, and Shuntaro Yamazaki,
Simulating Competitive Interactions using Singly Captured Motions ”,
Proc. ACM symposium on Virtual Reality Software and Technology, pp.65-72,
November 2007.
[Paper ] [Movie ] [Presentation] [BibTex ]

Supplementary Material

This short movie demonstrates the competitive interaction between multiple characters. A strong fighter in green keeps knocking down many opponents in blue. Notice that the opponents also interact one another when falling down. A color circle on the floor shows the interaction generated by a single patch.

Cooperative interaction of multiple characters can also be generated in our framework. In this movie, many people hand over sphere-shaped baggage to others continuously.

Our system allows a user to control characters using high-level commands such as direction or orientation. In this movie clip, the user specifies the direction of an American football player by a simple user interface shown in yellow.

In this clip a crowd continuously falls down drawing a SIGGRAPH logomark.