New algorithms for two-frame structure from motion

We describe two new algorithms for two-frame structure from motion from tracked point features. One is the first fast algorithm for computing an exact least-squares estimate. It exploits our observation that the rotationally invariant least-squares error can be written in a simple form that depends just on the motion. The other is essentially as accurate as the least-squares estimate and is more efficient, probably faster, and potentially more robust than previous algorithms of comparable accuracy. We also analyze theoretically the accuracy of the optical-flow approximation to the least-squares error.