Abstract
Marine biologists use a measurement called the “Dorsal Ratio” in the process of manual identification of bottlenose dolphins. The dorsal ratio denotes the relative distances of the two largest notches from the tip on the dorsal fin. The manual computation of this ratio is time consuming, labor intensive, and user dependent. This paper presents a computer-assisted system to extract the dorsal ratio for use in identification of individual animals. The first component of the system consists of active contour modeling where the trailing edge of the dorsal fin is detected. This is followed by a curvature module to find the characteristic fin points: tip and two most prominent notches. Curvature smoothing is performed at various smoothing scales, and wavelet coefficients are utilized to select an appropriate smoothing scale. The dorsal ratio is then computed from the curvature function at the appropriate smoothing scale. The system was tested using 296 digitized images of dolphins, representing 94 individual dolphins. The results obtained indicate that the computer extracted dorsal ratio can be used in place of the manually extracted dorsal ratio as part of the manual identification process. © 1999 Biomedical Engineering Society.
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REFERENCES
Araabi, B. N., N. Kehtarnavaz, G. Hillman, and B. Würsig. Generalization of dorsal ratio for dolphin photoidentification. Proceeding of the International Conference on Imaging Science, Systems, and Technology, Las Vegas, Nevada, June 1999.
Babaud, J., A. P. Witkin, M. Baudin, and R. O. Duda. Uniqueness of Gaussian Kernel for Scale Space Filtering. IEEE Trans. Pattern. Anal. Mach. Intell. 8:26–33, 1986.
Bergholm, F. Edge Focusing. IEEE Trans. Pattern. Anal. Mach. Intell. 9:726–741, 1987.
Beus, H. L., and S. H. Tiu. An Improved Corner Detection Algorithm Based on chin-Coded Plane Curves. Pattern Recogn. 20:291–296, 1987.
Buijs, R. J. C., and M. S. Huizinga. Automatic Photo-Identification of Bottlenose Dolphins. The Netherlands: Delft University of Technology, 1992.
Cheng, F., and W. Hsu. Parallel Algorithms for Corner Finding on Digital Curves. Pattern Recogn. Lett. 8:47–53, 1988.
Chui, C. K. An Introduction to Wavelets. New York: Academic, 1992.
Daubechies, I. Ten Lectures on Wavelets. Philadelphia, PA, Society for Industrial and Applied Mathematics: 1992.
Defran, R., G. Shultz, and D. Weller. A technique for the photographic identification and cataloging of dorsal fins of the bottlenose dolphin (Tursiops truncatus), in Individual Recognition of Cetaceans: Use of Photo Identification and other Techniques to Estimate Population Parameters, Report of the International Whaling Commission, Special Issue 12, June 1990, Cambridge University Press, pp. 53–55.
Freeman, H., and L. S. Davis. A Corner-Finding Algorithm for Chain Coded Curves. IEEE Trans. Comput. 26:297–303, 1977.
Gonzalez, R. C., and R. C. Woods. Digital Image Processing. Reading, MA: Addison-Wesley, 1992.
Hillman, G., H. Tagare, K. Elder, A. Drobyshevski, D. Weller, and B. Würsig. Shape descriptors computed from photographs of dolphin dorsal fins for use as database indices. Proceedings of the 20th Annual International Conference of IEEE EMB Society, 1998, Vol. 20, pp. 970–973.
Kass, M., A. Witkin, and D. Terzopoulos. Snakes: Active contour models. Int. J. Comput. Vis. 1:321–331, 1988.
Marr, D., and E. Hildreth. Theory of edge detection. Proc. R. Soc. London 207:187–217, 1980.
Mizroch, S. A., J. A. Beard, and M. Lynde. Computer-assisted Photo-Identification of Humpback Whales, in Individual Recognition of Cetaceans: Use of Photo Indentification and other Techniques to Estimate Population Parameters, Report of the International Whaling Commission, Special Issue 12, June 1990, Cambridge University Press, pp. 63–70.
Mokhatarian, F. Silhouette-Based Isolated Object Recognition Through Curvature Scale Space. IEEE Trans. Pattern. Anal. Mach. Intell. 17:539–544, 1995.
Mokhatarian, F., and A. Mockworth. Scale-Based Description and Recognition of Planar Curves and Two-Dimensional Shapes. IEEE Trans. Pattern. Anal. Mach. Intell. 8:34–43, 1986.
Poggio, T., H. Voorhees, and A. A. Yuille. Regularized Solution to Edge Detection. Technical report, AIM-833, MIT Artificial Intelligence Laboratory, 1985.
Schalkoff, R. Digital Image and Computer Vision. New York: Wiley, 1989.
Weller, D. W. The social ecology of Pacific coast bottlenose dolphins. M.Sc. Thesis, San Diego State University, San Diego, CA, 1999.
Weller, D. Global and regional variation in the biology and behavior of bottlenose dolphins. Ph.D. Dissertation, Department of Wildlife and Fisheries Sciences, Texas A & M University, 1998.
Whitehead, H. Computer-assisted individual identification of sperm whale flukes, in Individual Recognition of Cetaceans: Use of Photo Identification and other Techniques to Estimate Population Parameters, Report of the International Whaling Commission, Special Issue 12, June 1990, Cambridge University Press, pp. 71–77.
Williams, D., and M. Shah. A fast algorithm for active contours. Proceeding of 3rd IEEE International Conference on Computer Vision, 1990, pp. 592–595.
Würsig, B., and T. A. Jefferson. Methods of photoidentification for small cetaceans. In Individual Recognition of Cetaceans: Use of Photo Identification and other Techniques to Estimate Population Parameters, Report of the International Whaling Commission, Special Issue 12, June 1990, Cambridge University Press, pp. 43–52.
Würsig, B., and M. Würsig. The photographic determination of group size, composition, and stability of coastal porpoises (Tursiops truncatus). Science 198:755–776, 1977.
Xu, C., and J. L. Prince. Snakes, Shapes, and Gradient Vector Flow. IEEE Trans. Image. Process. 7:359–369, 1998.
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Kreho, A., Kehtarnavaz, N., Araabi, B. et al. Assisting Manual Dolphin Identification by Computer Extraction of Dorsal Ratio. Annals of Biomedical Engineering 27, 830–838 (1999). https://doi.org/10.1114/1.235
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DOI: https://doi.org/10.1114/1.235