Individualized reaction movements for virtual humans

ABSTRACT

Virtual Humans creation aims to provide virtual characters with realistic behavior, which implies endowing them with autonomy in an inhabited virtual environment. Autonomous behavior consists in interacting with users or the environment and reacting to stimulus or events. Reactions are unconscious behaviors which are not often implemented in virtual humans. Frequently, virtual humans show repetitive and robotic movements which tend to decrease realism.To improve believability in virtual humans we need to provide individuality. Individualization is achieved by using human characteristics like personality, gender, emotions, etc. In this paper, we propose to use those individual descriptors to synthesize different kinds of reactions. We aim that individualized virtual humans react in a different way to the same stimuli. This approach is achieved by observing real people reacting. Thanks to those observations, we stereotyped reactive movements that can be described by individual characteristics. We use inverse kinematics techniques to synthesize the movements. This allows us to change reaction movements according to the characteristics of the stimuli and to the individuality of a character.

REFERENCES

• 1: Norman I. Badler , Diane M. Chi , Sonu Chopra, Virtual Human Animation Based on Movement Observation and Cognitive Behavior Models, Proceedings of the Computer Animation, p.128, May 26-28, 1999
• 2: Baerlocher, P., and Boulic, R. 1998. Task-priority formulations for the kinematic control of highly redundant articulated structures. In Proceedings of IEEE Conference Intelligent Robots and Systems IROS 98, 323--329.
• 3: Baerlocher, P., and Boulic, R. 2000. Kinematic control of the mass properties of redundant articulated bodies. In Proceedings of IEEE Conference on Robotics and Automation, ICRA 2000, 2557--2562.
• 4: Paolo Baerlocher , Ronan Boulic, An inverse kinematics architecture enforcing an arbitrary number of strict priority levels, The Visual Computer: International Journal of Computer Graphics, v.20 n.6, p.402-417, August 2004 [doi>10.1007/s00371-004-0244-4]
• 5: Boulic, R., Mas, R., and Thalmann, D. 1996. A robust approach for the control of the center of mass with inverse kinetics. Computers and Graphics 20, Issue 5, Mobile Computing (September-October), 693--701.
• 6: Toni Conde , Daniel Thalmann, Autonomous virtual agents learning a cognitive model and evolving, Lecture Notes in Computer Science, Springer-Verlag, London, 2005 [doi>10.1007/11550617_8]
• 7: Patrick Doyle, Believability through context using "knowledge in the world" to create intelligent characters, Proceedings of the first international joint conference on Autonomous agents and multiagent systems: part 1, July 15-19, 2002, Bologna, Italy [doi>10.1145/544741.544822]
• 8: Faloutsos, P., Van De Panne, M., and Terzopoulos, D. 2001. The virtual stuntman: dynamic characters with a repertoire of autonomous motor skills. Computers and Graphics 25, 6, 933--953.
• 9: Garcia-Rojas, A., Thalmann, D., Vexo, F., Moccozet, L., Magnenat-Thalmann, N., Mortara, M.; Spagnuolo, M., and Gutierrez, M. 2005. An ontology of virtual humans: incorporating semantics into human shapes. In Integration of Knowledge, Semantics and Digital Media Technology. The 2nd European Workshop on the (Ref. No. 2005/11099)., 7--14.
• 10: A. García-Rojas , F. Vexo , D. Thalmann , A. Raouzaiou , K. Karpouzis , S. Kollias , L. Moccozet , N. Magnenat-Thalmann, Emotional face expression profiles supported by virtual human ontology: Research Articles, Computer Animation and Virtual Worlds, v.17 n.3‐4, p.259-269, July 2006 [doi>10.1002/cav.v17:3/4]
• 11: Gruber, T. R. 1991. The role of a common ontology in achieving sharable, reusable knowledge bases. In Proceedings of the Second International Conference on Principles of Knowledge Representation and Reasoning, 601--602.
• 12: Gutierrez, M., Vexo, F., and Thalmann, D. 2004. Reflex movements for a virtual human: a biology inspired approach. In SETN 2004: Proceedings of the 3rd Hellenic Conference on Artificial Intelligence, Special Session on Intelligent Virtual Environments, 525--534.
• 13: Gutiérrez, M., Vexo, F., and Thalmann, D. 2005. Semantics-based representation of virtual environments. In International Journal of Computer Applications in Technology (IJ-CAT) Special issue - "Models and methods for representing and processing shape semantics" (to appear).
• 14: Taku Komura , Edmond S. L. Ho , Rynson W. H. Lau, Animating reactive motion using momentum-based inverse kinematics: Motion Capture and Retrieval, Computer Animation and Virtual Worlds, v.16 n.3-4, p.213-223, July 2005 [doi>10.1002/cav.v16:3/4]
• 15: Leon, J.-C., Giannini, F., Falcidieno, B., Brunetti, G., Graf, H., Stork, A., Vexo, F., and Thalmann, D. 2005. Acquiring, structuring shapes and annotating them with semantics to improve design activities. In Proceedings of Virtual Concept, H. S. aris, Berlin, Ed., 10.
• 16: McCrae, R. R., and John, O. P. 1992. An introduction to the five-factor model and its applications. Journal of Personality, 60, 175--215.
• 17: Ponder, M., Papagiannakis, G., Molet, T., Magnenat-Thalmann, N., and Thalmann, D. 2003. Vhd++ development framework: Towards extendible, component based vr/ar simulation engine featuring advanced virtual character technologies, cgi 00, 96.
• 18: Tang, B., Pan, Z., Zheng, L., and Zhang, M. 2006. Simulating reactive motions for motion capture animation. In Advances in Computer Graphics, LNCS 4035, Springer, 531--537.
• 19: Zagal, J., Mateas, M., Fernández-Vara, C., Hochhal-Ter, B., and Lichti, N. 2005. Towards an ontological language for game analysis. In DIGRA Conf.
• 20: Victor Brian Zordan , Jessica K. Hodgins, Motion capture-driven simulations that hit and react, Proceedings of the 2002 ACM SIGGRAPH/Eurographics symposium on Computer animation, July 21-22, 2002, San Antonio, Texas [doi>10.1145/545261.545276]

INDEX TERMS

Primary Classification:
  H. Information Systems
  H.5 INFORMATION INTERFACES AND PRESENTATION (I.7)
      H.5.1 Multimedia Information Systems
          Subjects: Artificial, augmented, and virtual realities

Additional Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.7 Three-Dimensional Graphics and Realism
          Subjects: Virtual reality
  I.6 SIMULATION AND MODELING
      I.6.5 Model Development

Keywords:
reaction movement, semantic model, virtual humans animation