Motion Estimation of Visual Stimuli

Introduction

Neurobiologists and people studying animal behavior often want to present visual stimuli to animals(1). Characterizing the motion of a stimulus for comparision with other stimuli is not well defined at present. We are attempting to figure out a scheme for measuring the strength or intensity of a motion sequence. The first application is in spider visual courting displays.

Possible Methods

There are several ways of estimating motion. The two basic approaches are object based (e.g. 2) and image based methods. Object based methods use information about the 3D geometry of the structure generating the motion to estimate parameters such as joint rotation or limb velocity. Image based methods use only the information that might be available from a single video tape, or that might be observed by an animal under test. We chose to concentrate on image based methods because we need to compare video sequences as well as computer graphic models of spiders.

Two separate image based schemes were implemented:

The programs

The following matlab programs implemented the various features noted above. In all cases a slightly downsampled version of the animation was used for analysis.

New material since this Journal Club presentation

References

  1. Jacky Dragon ref
  2. Agrawala M, et.al., Model-based motion estimation for synthetic animations, http://www-graphics.stanford.edu/ and ACM Multimedia 1995
  3. Beauchemin SS and Barron JL, The Computation of optical Flow, ACM Computing Surveys, Vol 27, No 3, pp 433-467, 1995