Perceptual metrics for character animation: sensitivity to errors in ballistic motion

ABSTRACT

Motion capture data and techniques for blending, editing, and sequencing that data can produce rich, realistic character animation; however, the output of these motion processing techniques sometimes appears unnatural. For example, the motion may violate physical laws or reflect unreasonable forces from the character or the environment. While problems such as these can be fixed, doing so is not yet feasible in real time environments. We are interested in developing ways to estimate perceived error in animated human motion so that the output quality of motion processing techniques can be better controlled to meet user goals.This paper presents results of a study of user sensitivity to errors in animated human motion. Errors were systematically added to human jumping motion, and the ability of subjects to detect these errors was measured. We found that users were able to detect motion with errors, and noted some interesting trends: errors in horizontal velocity were easier to detect than errors in vertical velocity, and added accelerations were easier to detect than added decelerations. On the basis of our results, we propose a perceptually based metric for measuring errors in ballistic human motion.

REFERENCES

• 1: BINGHAM, G. P. 1987. Kinematic form and scaling: Further investigations on the visual perception of lifted weight. Journal of Experimental Psychology: Human Perception and Performance 13, 2, 155--177.
• 2: HECHT, H., AND BERTAMINI, M. 2000. Understanding projectile acceleration. Journal of Experimental Psychology: Human Perception and Performance 26, 2, 730--746.
• 3: Jessica K. Hodgins , James F. O'Brien , Jack Tumblin, Perception of Human Motion With Different Geometric Models, IEEE Transactions on Visualization and Computer Graphics, v.4 n.4, p.307-316, October 1998 [doi>10.1109/2945.765325]
• 4: KAISER, M. K., PROFFITT, D. R., WHELAN, S. M., AND HECHT, H. 1992. Influence of animation on dynamical judgments. Journal of Experimental Psychology: Human Perception and Performance 18, 3, 669--690.
• 5: LEVITT, H. 1971. Transformed up-down methods in psychoacoustics. Journal of the Acoustical Society of America 49, 467--477.
• 6: MACMILLAN, N. A., AND CREELMAN, C. D. 1991. Detection Theory: A User's Guide. Cambridge University Press, New York.
• 7: MICHAELS, C. F., AND DE VRIES, M. M. 1998. Higher order and lower order variables in the visual perception of relative pulling force. Journal of Experimental Psychology: Human Perception and Performance 24, 2, 526--546.
• 8: OESKER, M., HECHT, H., AND JUNG, B. 2000. Psychological evidence for unconscious processing of detail in real-time animation of multiple characters. Journal of Visualization and Computer Animation 11, 105--112.
• 9: Carol O'Sullivan , John Dingliana, Collisions and perception, ACM Transactions on Graphics (TOG), v.20 n.3, p.151-168, July 2001 [doi>10.1145/501786.501788]
• 10: PROFFITT, D. R. 1999. Naive physics. In The MIT Encyclopedia of the Cognitive Sciences, R. Wilson and F. Keil, Eds. MIT Press, 577--579.
• 11: RUNESON, S., AND FRYKHOLM, G. 1981. Visual perception of lifted weight. Journal of Experimental Psychology: Human Perception and Performance 7, 4, 733--740.
• 12: STAPPERS, P. J., AND WALLER, P. E. 1993. Using the free fall of objects under gravity for visual depth estimation. Bulletin of the Psychonomic Society 31, 2, 125--127.
• 13: Benjamin Watson , Alinda Friedman , Aaron McGaffey, Measuring and predicting visual fidelity, Proceedings of the 28th annual conference on Computer graphics and interactive techniques, p.213-220, August 2001 [doi>10.1145/383259.383283]

INDEX TERMS

Primary Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.7 Three-Dimensional Graphics and Realism
          Subjects: Animation

Keywords:
animation, evaluation, motion capture, perceptual metrics