Motion segmentation from optical flow

This note describes two different methods for motion segmentation from optical flow. In the first method, the Jacobian matrix of the first spatial derivatives of the components of optical flow is used to compute the amount of uniform expansion, pure rotation, and shear at every flow point. In the second description, local properties of optical flow which are invariant for non-singular linear transformation are computed from the trace and the determinant of the matrix itself. Both the methods allow to distinguish between different kinds of motion, like translation, rotation, and relative motion in sequences of time-varying images. Preliminary results show that they can also be useful to identify the different moving objects in the viewed scene.