Motion sensing of a portable device using two cameras. A first camera is directed along a first viewing axis and a second camera is directed along a second viewing axis, different from the first viewing axis. The second viewing axis can be substantially opposite the first viewing axis. A motion processing module determines changes in images from the first camera and changes in images from the second camera. The motion processing module compares the direction of change determined from the first camera images relative to the direction of change determined from the second camera images. The motion processing module determines the motion of the portable device based in part on the comparison.