Collision Avoidance between Avatars of Real and Virtual Individuals

  • René van den Berg
  • Juan Manuel Rejen
  • Rafael Bidarra
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5884)


One of the most difficult challenges of associating virtual environments and real-world events deals with integrating real-world, tracked individuals into a virtual environment: while virtual individuals may interact with the avatars of real-world individuals, the latter obviously do not respond to the behaviour of the virtual individuals. To prevent collisions or unrealistic behaviour of either, one needs to ‘artificially’ modify the trajectory of the tracked individual. Moreover, after such modifications, one should end up returning that avatar back to the accurate representation of the real world.

In this paper we propose a strategy for solving these problems based on generic control functions, which are flexible enough to be fine-tuned on a domain- dependent basis. Control functions determine an offset from the tracked individual’s actual trajectory and, when carefully parameterized, guarantee a smooth and automatic recovery after each trajectory modification. We discuss this approach, illustrate it with a variety of Gaussian control functions, analyze the believability of the resulting trajectory modifications, and conclude that control functions provide a sound and powerful basis for improving strategies of collision-avoiding trajectory modification and recovery. Most examples of domain-specific strategies discussed here are taken from the upcoming application area of real-time racing games, which provides both easily recognizable and very attractive situations, and has been the original motivation for this research.


Trajectory modification collision evasion real-world integration 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    DeCarpentier, G.J.P., Bidarra, R.: Behavioral assumption-based prediction for high-latency hiding in mobile games. In: Proceedings CGAMES 2007 (2005)Google Scholar
  2. 2.
    Delaney, D., Ward, T., Mcloone, S.: On reducing entity state update packets in distributed interactive simulations using a hybrid model. In: Proceeding of the 21st IASTED International Multi-conference on Applied Informatics, pp. 10–13 (February 2003)Google Scholar
  3. 3.
    Gayle, R., Sud, A., Lin, M., Manocha, D.: Reactive deformation roadmaps: motion planning of multiple robots in dynamic environments. In: IEEE/RSJ International Conference on Intelligent Robots and Systems, IROS 2007, pp. 3777–3783 (2007)Google Scholar
  4. 4.
    Gossweiler, R., Laferriere, R., Keller, M., Pausch, R.: An introductory tutorial for developing multiuser virtual environments. Presence: Teleoperators and Virtual Environments 3(4), 255–264 (1994)Google Scholar
  5. 5.
    System for Simulating Events in a Real time Environment, U.S. Patent Application No. 12/106,263; for more information contact iOpener Media,
  6. 6.
    Li, S., Chen, C., Li, L.: A new method for path prediction in network games. Comput. Entertain. 5(4), 1–12 (2007)zbMATHCrossRefGoogle Scholar
  7. 7.
    Musse, S., Thalmann, D.: A hierarchical model for real time simulation of virtual human crowds. IEEE Transactions on Visualization and Computer Graphics 7(2), 152–164 (2001)CrossRefGoogle Scholar
  8. 8.
    Pantel, L., Wolf, L.: On the suitability of dead reckoning schemes for games. In: NetGames 2002: Proceedings of the 1st workshop on Network and system support for games, pp. 79–84. ACM, New York (2002)CrossRefGoogle Scholar
  9. 9.
    Reif, J., Sharir, M.: Motion planning in the presence of moving obstacles. J. ACM 41(4), 764–790 (1994)zbMATHCrossRefGoogle Scholar
  10. 10.
    Treuille, A., Cooper, S., Popović, Z.: Continuum crowds. In: SIGGRAPH 2006: ACM SIGGRAPH 2006 Papers, pp. 1160–1168. ACM, New York (2006)CrossRefGoogle Scholar
  11. 11.
    Van Den Berg, J., Patil, S., Sewall, J., Manocha, D., Lin, M.: Interactive navigation of multiple agents in crowded environments. In: SI3D 2008: Proceedings of the 2008 symposium on Interactive 3D graphics and games, pp. 139–147. ACM, New York (2008)CrossRefGoogle Scholar
  12. 12.

Copyright information

© Springer-Verlag Berlin Heidelberg 2009

Authors and Affiliations

  • René van den Berg
    • 1
  • Juan Manuel Rejen
    • 2
  • Rafael Bidarra
    • 1
  1. 1.Delft University of Technology 
  2. 2.iOpener Media GmbH 

Personalised recommendations