NOTE: A Multiscale Approach to Image Sequence Analysis

image analysis, the introduction of the notion of scale in motion analysis is far from trivial. In optic flow based In optic flow based velocity estimation the image brightness constraint equation is used. However, for measurements pervelocity estimation, correspondences between adjacent formed at a certain scale, the brightness constraint equation frames are made using the image brightness constraint does not apply. We therefore use a recently developed approach equation [5–11]. However, this constraint applies to image which reconciles optic flow and scale space theory. It specifically isophotes, which are nonmeasurable. Only recently incorporates the scale (aperture) of image measurements, leadFlorack and Nielsen [12] derived the appropriate constraint ing to a scheme which is essentially different from existing equation for measurements at a certain scale, thus reconcilapproaches. To obtain a unique velocity field, the data-derived ing optic flow and scale space theory. The approach leads information has to be augmented with physical knowledge. By to an order by order approximation of the optic flow field, keeping a strict separation between data-derived and external which only in the zeroth order corresponds to the conveninformation, we can locally adapt or modify the user-supplied tional Horn & Schunck Optic Flow Constraint Equation information without affecting the image-derived information. (OFCE) [5, 10]. In Section 4 we show an analytical study The two free scale parameters in time and space can be used which shows the virtue of higher order approximations. for attentive vision (selecting particular velocities or objects) Owing to the aperture problem [13, 14] (any motion and to improve the reliability of velocity estimates.  1997 along isophotes is possible without having a measurable Academic Press