An approach to the problem of range image segmentation is described. It is a hybrid of region- and edge-based approaches. It is assumed that the range image of an object, which may be constructed of both curved and pl...
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An approach to the problem of range image segmentation is described. It is a hybrid of region- and edge-based approaches. It is assumed that the range image of an object, which may be constructed of both curved and planar surfaces, is divided into surface primitives which are homogeneous in their intrinsic differential geometric properties and do not contain discontinuities in either depth or surface orientation. The method is based on the computation of the Gaussian and mean curvatures from which a curvature sign map is computed. Two initial edge-based segmentations are also computed from the partial derivatives and depth values. One detects jump edges while the other highlights roof edges. The three image maps are then combined to produce the final range image segmentation. Experimental results for both synthetic and real range data of polyhedral and curved objects have proved the usefulness of the approach. Results for the real data are given.< >
Orientation selection is the inference of orientation information out of images. It is one of the foundations on which other visual structures are built, since it must precede the formation of contours out of pointill...
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Orientation selection is the inference of orientation information out of images. It is one of the foundations on which other visual structures are built, since it must precede the formation of contours out of pointillist data and surfaces out of surface markings. We take a differential geometric view in defining orientation selection and develop algorithms for actually doing it. The goal of these algorithms is formulated in mathematical terms as the inference of a vector field of tangents (to the contours), and the algorithms are studied in both abstract and computational forms. They are formulated as matching problems, and algorithms for solving them are reduced to biologically plausible terms. We show that two different matching problems are necessary, the first for 1-dimensional contours (which we refer to as Type I processes) and the second for 2-dimensional flows (or Type II processes).
Robot tasks have come to demand flexible sensory-based "intelligent" behavior. The single robot has given way to multiple robots cooperating in three-dimensional dynamic environments which allow them to acco...
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Robot tasks have come to demand flexible sensory-based "intelligent" behavior. The single robot has given way to multiple robots cooperating in three-dimensional dynamic environments which allow them to accomplish complex and intricate tasks. Because of the complex nature of the tasks performed, centralized control is no longer practical; workcells have become centers of distributed computing. This motivates the need for an interprocess communication (IPC) facility which would integrate the individual elements both within and between workcells. A survey of IPC is presented in the context of distributed robotics. To make the survey more meaningful, it is introduced by some remarks about general approaches to communication within a distributed computing environment. A discussion of the main IPC design issues for distributed robotics is included.
We present an efficient method for detecting straight line segments in digital pictures using a hypothesis prediction/verification paradigm. In this paradigm, a straight line segment of predefined length is predicted ...
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We present an efficient method for detecting straight line segments in digital pictures using a hypothesis prediction/verification paradigm. In this paradigm, a straight line segment of predefined length is predicted to exist at some particular pixel location. The orientation of this predicted line segment is based on the edge orientation at the pixel location. This prediction is then verified against statistical tests performed on the line. As a result, the predicted line is either validated as being a line segment, or it is rejected. An extension of this algorithm for the detection of lines at different lengths is also presented, and a criterion is defined in order to evaluate the significance of the detected line segments.
Optical flow can be thought of as a generalization of orientation selection to include time, and this is a first attempt to develop this generalization. This paper is informal, and begins with an overview of a computa...
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Optical flow can be thought of as a generalization of orientation selection to include time, and this is a first attempt to develop this generalization. This paper is informal, and begins with an overview of a computational theory of orientation selection that has been developed in our laboratory during the past few years. A theory of optical flow computations is then sketched on the basis of this background, and a number of consequences important for both computational modeling and psychophysics are discussed. We concentrate in particular on two notions—dimensionality and structure—and describe a series of experiments that demonstrate that sensitivity to discontinuities in optical flow patterns has significant similarities to those in orientation patterns. Such similarities lend strong support to the analogy.
Neurons in the visual cortex typically respond selectively to the orientation, and velocity and direction of movement, of moving-bar stimuli. These responses are generally thought to provide information about the orie...
Neurons in the visual cortex typically respond selectively to the orientation, and velocity and direction of movement, of moving-bar stimuli. These responses are generally thought to provide information about the orientation and position of lines and edges in the visual field. Some cells are also endstopped, that is selective for bars of specific lengths. Hubel and Wiesel first observed that endstopped hypercomplex cells1could respond to curved stimuli and suggested they might be involved in detection of curvature, but the exact relationship between endstopping and curvature has never been determined. We present here a mathematical model relating endstopping to curvature in which the difference in response of two simple cells gives rise to endstopping and varies in proportion to curvature. We also provide physiological evidence that endstopped cells in area 17 of the cat visual cortex are selective for curvature, whereas non-endstopped cells are not, and that some are selective for the sign of curvature. The prevailing view of edge and curve determination is that orientations are selected locally by the class of simple cortical cells3and then integrated to form global curves. We have developed a computational theory of orientation selection4,5which shows that measurements of orientation obtained by simple cells are not sufficient because there will be strong, incorrect responses from cells whose receptive fields (RFs) span distinct curves (Fig. 1). If estimates of curvature are available, however, these inappropriate responses can be eliminated. Curvature provides the key to structuring the network that underlies our theory and distinguishes it from previous lateral inhibition schemes6,7.
Due to demographical factors, there will be a 25% decline in the national labor pool of eligible 17 to 21 year old men by 1992. As the Navy faces fierce competition with other services and private industry for the dwi...
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Due to demographical factors, there will be a 25% decline in the national labor pool of eligible 17 to 21 year old men by 1992. As the Navy faces fierce competition with other services and private industry for the dwindling personnel resources of the nation, efforts must be made to consider automating certain tasks, especially those that are hazardous, boring, and labor intensive onboard ships at sea. The Surface Ship Continuing Concept Formulation (CONFORM) Program (SEA-5014) sponsored the Naval Surface Weapons Center's robotics Laboratory to identify potential applications of robotic and artificial intelligence systems to operation and mission activities for shipboard use. The results of the investigation concerning applications of robotics to automate the aforementioned tasks are presented. Changes in current manning levels for selected tasks and ship classes, i.e., CVs, CVNs, LPDs, LPNs, and auxiliaries are examined. Future ship designs incorporating robotics, such as the advance based repair (ABR) ship are discussed. Twenty-four applications were cited in the study which include a remote controlled vehicle for flight deck operations, limited tasks in biological, chemical, and radiation environments, computer aided command decision aids, ordnance handling, undersea search, recovery, and salvage, and ventilation duct cleaning. Four of the applications and their subsequent hardware fruition will be discussed.
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