[...]... the type of motion, the image region in which the model applies, as well as the expected statistics of the image motion over time The more detailed and specified a model is and thus the more accurate it can describe a particular flow field, the more it lacks generality The choice of the model is determined by the image motion expected, the type of motion information required, and the complexity of the system... by the imaging devices It is the task of visual motion perception to interpret the spatio-temporal brightness pattern and extract image motion in a meaningful way This chapter will outline the computational problems involved in the perception of visual motion, and provide a rough concept of how a system for visual motion perception should be constructed The concept follows an ecological approach Visual. .. CMOS circuits The relevance of this book is that it describes the theory and practical implementation of constraint satisfaction networks for motion perception It also presents a principled xii FOREWORD development of a series of analog VLSI chips that go some way toward the solution of some difficult problems of visual perception, such as the Aperture Problem, and Motion Segmentation These classical... only the initial processing stage of visual perception and hardly operates on the notion of objects and context It simply transforms the visual environment into an image, which represents the spatially sampled measure of the radiance distribution in the visual scene observed Nevertheless, it is sensible to refer to the image as representing a brightness distribution of the visual scene, to denote the. .. with the shape of objects Thus, knowledge of the spatial position and extent of the light source enables further extraction of information about our environment Our world is also a world of motion We and most other animals are moving creatures We navigate successfully through a dynamic environment, and we use predominantly visual information to do so A sense of motion is crucial for the perception of. .. subjective task, constrained by the assumptions and models it applies 12 VISUAL MOTION PERCEPTION This raises the question of how to define a correct benchmark for visual motion systems Is a best possible estimation of the motion field the preferred goal? Well, as said before, this depends on the needs of the entire system In general, it seems sensible to extract the motion field as well as possible... subsequent (motion) systems can process Figure 2.1 schematically illustrates the imaging The scene consists of objects that are either direct (sun) or indirect (tree) sources of light, and their strength is characterized by the Analog VLSI Circuits for the Perception of Visual Motion  2006 John Wiley & Sons, Ltd A A Stocker 8 VISUAL MOTION PERCEPTION transducer optics (pin-hole) intensity brightness transduction... requires the divergence to be constant For approaching motion, the origin of the source is called focus of expansion and signals the heading direction of the observer Similarly for receding motion, the origin of the sink is called focus of contraction A single parameter c0 = div(v) is sufficient to describe the flow field where its sign indicates approaching or receding motion and its value is a measure for. .. allow for such arbitrary encoding of regions of support However, finding these regions reliably is a difficult computational problem For example, in the simple case of translational image motion, the outlines of the objects are the only regions where the image motion is discontinuous Thus, an accurate estimate of the image motion is sufficient to find motion discontinuities However, how can one extract motion. .. available were such circuits of practical interest 2 Visual Motion Perception Visual motion perception is the process an observer performs in order to extract relative motion between itself and its environment using visual information only Typically, the observer possesses one or more imaging devices, such as eyes or cameras These devices sense images that are the two-dimensional projection of the intensity . alt="" Analog VLSI Circuits for the Perception of Visual Motion Analog VLSI Circuits for the Perception of Visual Motion Alan A. Stocker Howard Hughes Medical Institute and Center for Neural. predominantly visual information to do so. A sense of motion is crucial for the perception of our own motion in relation to other moving and static objects in the environment. We must predict accurately the. book. I am grateful for his encouragement and support during the writing of the book. Most of the circuits developments were per- formed when I was with the Institute of Neuroinformatics, Z ¨ urich