First order optic flow from log-polar sampled images

The first-order spatial derivatives of optic flow — dilation, shear and rotation — provide powerful information about motion and surface layout. The log-polar sampled image (LSI) is of increasing interest for active vision, and is particularly well-suited to the measurement of local first-order flow. We explain why this is, propose a simple least-squares method for measuring first-order flow in an LSI sequence, and demonstrate that the method works well when applied to real images.