A robust method is introduced for computing the camera motion (the ego-motion) in a static scene. The method is based on detecting a single planar surface in the scene directly from image intensities, and computing its 2D motion in the image plane. The detected 2D motion of the planar surface is used to register the images, so that the planar surface appears stationary. The resulting displacement eld for the entire scene in such registered frames is a ected only by the 3D translation of the camera, which is computed by nding the focus-of-expansion in the registered frames. This step is followed by computing the 3D rotation to complete the computation of the ego-motion. This 3D motion computation is based on a motion computation scheme which handles the di cult case when multiple image motions are present. This multiple motion analysis is performed together with object segmentation by using a temporal integration approach.