“Photorealistic Models for Pupil Light RefIex and Iridal Pattern Deformation” by Pamplona, Oliveira and Baranoski

We introduce a physiologically-based model for pupil light reflex (PLR) and an image-based model for iridal pattern deformation. Our PLR model expresses the pupil diameter as a function of the lighting of the environment, and is described by a delay-differential equation, naturally adapting the pupil diameter even to abrupt changes in light conditions. Since the parameters of our PLR model were derived from measured data, it correctly simulates the actual behavior of the human pupil. Another contribution of our work is a model for realistic deformation of the iris pattern as a function of pupil dilation and constriction. Our models produce high-fidelity appearance effects and can be used to produce real-time predictive animations of the pupil and iris under variable lighting conditions. We assess the predictability and quality of our simulations through comparisons of modeled results against measured data derived from experiments also described in this work. Combined, our models can bring facial animation to new photorealistic standards.

1. Bergamin, O., Schoetzau, A., Sugimoto, K., and Zulauf, M. 1998. The influence of iris color on the pupillary light reflex. Graefes Arch Clin Exp Ophthalmol 236, 8, 567–570.
2. Calcagnini, G., Censi, F., Lino, S., and Cerutti, S. 2000. Spontaneous fluctuations of human pupil reflect central autonomic rhythms. Methods Inf. Med. 39, 2, 142–145.
3. Crawford, B. H. 1936. The integration of the glare effects from a number of glare sources. Proc. Phys. Soc. 48, 1, 35–37.
4. Cui, J., Wang, Y., Huang, J., Tan, T., and Sun, Z. 2004. An iris image synthesis method based on PCA and super-resolution. In Proceedings of the 17th International Conference of Pattern Recognition (ICPR). 471–474. 
5. de Groot, S. G. and Gebhard, J. W. 1952. Pupil size as determined by adapting luminance. J. Opt. Soc. Am. 42, 492–495.
6. Debevec, P. 2007. Paul debevec homepage. http://www.debevec.org/.
7. Ellis, C. J. 1981. The pupillary light reflex in normal subjects. Brit. J. Ophthal. 65, 11, 754–759.
8. Ferwerda, J. 2003. Three varieties of realism in computer graphics. In Proceedings of SPIE Human Vision and Electronic Imaging. The International Society for Optical Engineering, 290–297.
9. François, G., Gautron, P., Breton, G., and Bouatouch, K. 2007. Anatomically accurate modeling and rendering of the human eye. In Special Interest Group on Graphics and Interactive Techniques (SIGGRAPH): Sketches. ACM, New York, 59. 
10. Freddo, T. 1996. Ultrastructure of the iris. Micros. Res. Tech. 33, 369–389.
11. Hachol, A., Szczepanowska-Nowak, W., Kasprzak, H., Zawojska, I., Dudzinski, A., Kinasz, R., and Wygledowska-Promienska, D. 2007. Measurement of pupil reactivity using fast pupillometry. Physiol. Meas. 28, 61–72.
12. Hess, E. H. and Polt, J. M. 1964. Pupil size in relation to mental activity during simple problem-solving. Science 143, 1190–1192.
13. Hill, A. V. 1938. The heat of shortening and the dynamic constants of muscle. Proc. R. Soc. London B. Biol. Sci. 126, 136–195.
14. Lam, M. W. Y. and Baranoski, G. V. G. 2006. A predictive light transport model for the human iris. Comput. Graph. Forum 25, 3, 359–368.
15. Lee, S., Badler, J., and Badler, N. 2002. Eyes alive. ACM Trans. Graph. 21, 3, 637–644. 
16. Lefohn, A., Budge, B., Shirley, P., Caruso, R., and Reinhard, E. 2003. An ocularist’s approach to human iris synthesis. IEEE Comput. Graph. Appl. 23, 6, 70–75. 
17. Li, Z., Liang, P., and Sun, F. 2006. Properties of pupillary responses to dynamic random-dot stereograms. Exp. Brain Res. 168, 436–440.
18. Link, N. and Stark, L. 1988. Latency of the pupillary response. IEEE Trans. Bio. Eng. 35, 3, 214–218.
19. Longtin, A. and Milton, J. G. 1989. Modelling autonomous oscilations in the human pupil light reflex using nonlinear delay-differential equations. Bull. Math. Bio. 51, 5, 605–624.
20. Lowenstein, O. and Loewenfeld, I. E. 1964. The sleep-waking cycle and pupillary activity. Annals NY Acad. Sci. 117, 142–156.
21. Makthal, S. and Ross, A. 2005. Synthesis of iris images using Markov random fields. In Proceedings of the European Signal Processing Conference (EUSIPCO).
22. Moon, P. and Spencer, D. 1944. On the Stiles-Crawford Effect. J. Opt. Soc. Am. 34, 319–329.
23. Newsome, D. and Loewenfeld, I. 1971. Iris mechanics. ii. influence of pupil size on dynamics of pupillary movements. Am. J. Ophthalmol. 71, 1 Part 2, 353–373.
24. Nicodemus, F. E., Richmond, J. C., Hsia, J. J., Ginsberg, I. W., and Limperis, T. 1977. Geometrical considerations and nomenclature for reflectance. Tech. Rep., Institute for Basic Stds. (Oct). National Bureau of Stds, Washington, DC.
25. Ohta, N. and Robertson, A. 2005. Colorimetry: Fundamentals and Applications. John Wiley&Sons, New York.
26. Oliveira, M. M. and Policarpo, F. 2005. An efficient representation for surface details. Tech. rep. RP-351, UFRGS, Porto Alegre, Brazil.
27. Partridge, L. D. and Benton, L. A. 1981. Handbook of Physiology, Motor Control. Vol. 2. Chapter Muscle: The Motor. American Physiological Society, Washington, 43–106.
28. Pokorny, J. and Smith, V. C. 1997. The verriest lecture. How much light reaches the retina? In C.R. Cavonius, Ed. Colour Vision Deficiencies XIII. Doc. Ophth. Proc. Series 59. 491–511.
29. Policarpo, F., Oliveira, M. M., and Comba, J. L. D. 2005. Real-time relief mapping on arbitrary polygonal surfaces. In Proceedings of the Symposium on Interactive 3D Graphics and Games. ACM, New York, NY, 155–162. 
30. Reeves, P. 1920. The response of the average pupil to various intensities of light. J. Opt. Soc. Am. 4, 2, 35–43.
31. Rohen. 1951. Der bau der regenbogenhaut beim menschen und einigen sÔugern. Gegenbaur Morphology J. 91, 140–181.
32. Sagar, M., Bullivant, D., Mallinson, G., Hunter, P., and Hunter, I. 1994. A virtual environment and model of the eye for surgical simulation. In Proceedings of the Special Interest Group on Graphics and Interactive Techniques (SIGGRAPH), Annual Conference Series. 
33. Stark, L. W. 1939. Stability, oscillations, and noise in the human pupil servomechanism. Proc. IRE 47, 11, 1925–1939.
34. Stark, L. W. and Sherman, P. M. 1959. A servoanalytic study of consensual pupil reflex to light. J. Neurophysiol. 20, 17–26.
35. Thomson, L. C. 1947. Binocular summation within the nervous pathways of the PLR. J. Physiology 106, 59–65.
36. Tilmant, C., Charavel, M., Ponrouch, M., Gindre, G., Sarry, L., and Boire, J.-Y. 2003. Monitoring and modeling of pupillary dynamics. Proceedings of 25th IEEE EMBS 1, 678–681.
37. Trevor-Roper, P. D. and Curran, P. V. 1984. The Eye and Its Disorders. Vol. 3. Chapter The Eyeball. Blackwell Scientific Publications, Oxford, UK, 3–75.
38. Tryon, W. W. 1975. Pupillometry: A survey of sources of variation. Psychophysiology 12, 1, 90–93.
39. Turbo Squid. 2007. 3d max male face head. http://www.turbosquid.com/FullPreview/Index.cfm/ID/357993.
40. Ukai, K., Tsuchiya, K., and Ishikawa, S. 1997. Induced pupillary hippus following near vision: increased occurrence in visual display unit workers. Ergonomics 40, 11, 1201–1211.
41. Usui, S. and Stark, L. 1982. A model for nonlinear stochastic behavior of the pupil. BioCyber 45, 1, 13–21.
42. Ventura, B., Lemerle, C., Michalodimitrakis, K., and Serrano, L. 2006. From in vivo to in silico biology and back. Nature 443, 527–533.
43. Watt, A. and Watt, M. 1992. Advanced Animation and Rendering Techniques. Addison-Wesley, New York.
44. Wecker, L., Samavati, F., and Gavrilova, M. 2005. Iris synthesis: a reverse subdivision application. In Proceedings of the International Conference on Computer Graphics and Interactive Techniques (GRAPHITE), 121–125. 
45. Werner, A. 2003. Spectral sensitivity of the pupillary system. Clin. Exp. Optom. 86, 4, 235–238.
46. Winn, B., Whitaker, D., Elliott, D. B., and Phillips, N. J. 1994. Factors affecting light-adapted pupil size in normal human subjects. Invest. Opthmol. Vis. Sci. 35, 3.
47. Wyatt, H. J. 2000. A minimum-wear-and-tear meshwork for the iris. Vision Res. 40, 2167–2176.
48. Zuo, J. and Schmid, N. A. 2005. A model based, anatomy based method for synthesizing iris images. In Proceedings of IAPR International Conference on Biometrics. 428–435.