Mitiche and Bouthemy 1984 : The general context of this work is dynamic scene analysis which, in broad terms, is concerned with the processing of time-ordered sequences of images called dynamic images. More precisely, we are interested in determining three-dimensional object structure and motion from a time-ordered sequence of stereoscopic pairs of two-dimensional images. Of interest here are point-structures. We will limit ourselves to 4-point structures because, in our context, we need 4 points to solve for motion. The basic assumption is that we are given a rigid structure of four non-coplanar points for which the following is known: Its internal orientation and the distance between each pair of its points. Briefly , the internal orientation of a point-structure is related to the triple product of vectors associated with the edges between points of this structure. A formal definition will be given in the next section. Monocular views of point-structures have been used in several studies to determine the three-dimensional structure and movement of objects. Also, point structures have been of practical interest in several studies. For example, monocular views of object points have been used in the context of video coding, space-shuttle remote manipulation and for the study of sprung-mass response of vehicles in collision with highway barriers. As well, the measurement of position of objects from binocular imaging, or stereopsis, has been the topic of many studies. Practical applications include cartographic mapping, passive navigation, and modeling of the human visual system.