COMPUTATIONAL ANALYSIS OF NON-FOURIER MOTION

Non-Fourier motion is now commonplace in research on visual motion per ception, yet lacks a computational framework. This paper examines this issue based on the observation that many non-Fourier motion stimuli h ave a simple characterization in the frequency domain, in terms of ori ented power distributions that lie along lines (or planes) that do not pass through the origin. This provides a unifying theoretical framewo rk for a very diverse class of non-Fourier phenomena. It also allows u s to examine some central issues concerning the computational nature o f non-Fourier models, and naturally occurring sources of non-Fourier m otion. For example, it is shown that the orientation of power in frequ ency domain corresponds to the velocity of a multiplicative envelope, and may arise as a restricted form of lighting effects, translucency o r occlusion. We also show that both the location and orientation of sp ectral power may be extracted from the phase and amplitude output of b and-pass filters, consonant with existing non-Fourier models.