Velocity estimation and comparison of two insect vision based motion detection models Sreeja Rajesh", David OCarroI1a and Derek Abbottb aDepartment of Physiology and Department of Electrical & Electronic Engineering and Centre for Biomedical Engineering, Adelaide University, SA-5005, Australia bDepartment of Electrical & Electronic Engineering and Centre for Biomedical Engineering, Adelaide University, SA-5005, Australia ABSTRACT Insects are blessed with a very efficient yet simple visual system which enable them to navigate with great ease and accuracy. Though a lot has been done in the field of insect vision, there is still not a clear understanding of how velocity is determined in biological vision systems. The dominant model for insect motion detection, first proposed by Hassentein and Reichardt in 1956 has gained widespread acceptance in the invertebrate vision community. The template model, proposed later by Horridge in 1990, permits simple tracking techniques and lends itself easily to both hardware and software, Analysis and simulations by Dror suggest that the inclusion of additional system components to perform pre-filtering, response compression, integration and adaptation, to a basic Reichardt correlator can make it less sensitive to contrast and spatial structure thereby providing a more robust estimate of local image velocity. It was found from the data obtained, from the intracellular recordings of the steady state responses of wide field neurons in the hoverfiy Volucella, that the shape of the curves obtained, agreed perfectly with the theoretical predictions made by Dror. In order to compare it with the template model, an experiment was done to get the velocity response curves of the template model using the same image statistics. The results leads us to believe that the fly motion detector emulates a modified Reichardt correlator. Keywords: Reichardt correlator, template model, motion detection, velocity estimation 1. INTRODUCTION Anyone who has watched a group of bees flying together, would be marveled by their amazing ability to fly with such great speed without colliding into one another. The activities of insects clearly reveal the extraordinary navigational skills that the insects possess despite the fact that they have a very simple visual system. The study of the insect visual system has offered solutions to a number of problems faced by the conventional machine vision systems and has led to many elegant strategies that can be profitably applied to motion detection,' velocity estimation,2 and has even be used in the design of collision avoidance sensors3 and autonomous Further author information: (Send correspondence to Sreeja Rajesh) Sreeja Rajesh: E-mail: srajesh@eleceng.adelaide.edu.au, Telephone: 83036296 David O'Carroll: E-mail: david.ocarroll@adelaide.edu.au Derek Abbott: E-mail: dabbott@eleceng.adelaide.edu.au Smart Materials, Structures, and Systems, S. Mohan, B. Dattaguru, S. Gopalakrishnan, Editors, Proceedings of SPIE Vol. 5062 (2003) © 2003 SPIE · 0277-786X/03/$15.00 401 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 11/15/2012 Terms of Use: http://spiedl.org/terms