For general objects, and for illumination from a general direction, the constraints on shape imposed by shading are studied. It is argued that, for a typical image, shading determines shape essentially up to a finite ...
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ISBN:
(纸本)0818621486
For general objects, and for illumination from a general direction, the constraints on shape imposed by shading are studied. It is argued that, for a typical image, shading determines shape essentially up to a finite ambiguity. Thus regularization is often unnecessary and should be avoided. For some images, shape from shading is a partially well-constrained problem: the surface is uniquely determined over most of the image, but infinitely ambiguous in small regions bordering the image boundary, even though the image contains singular points. The main result is that, contrary to previous belief, the image of the occluding boundary does not strongly constrain the surface solution. It is shown that characteristic strips are curves of steepest ascent on the imaged surface. A theorem characterizing the properties of generic images is presented.
The Bayesian segmentation model developed is motivated by consideration of the information needed for higher-level visual processing. A segmentation is regarded as a collection of parameters defining an image-valued s...
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ISBN:
(纸本)0818621486
The Bayesian segmentation model developed is motivated by consideration of the information needed for higher-level visual processing. A segmentation is regarded as a collection of parameters defining an image-valued stochastic process by separating topological (adjacency) and metric (shape) properties of the subdivision and intensity properties of each region. The prior selection is structured accordingly. The novel part of the representation, the subdivision topology, is assigned a prior by universal coding arguments, using the minimum description-length philosophy that the best segmentation allows the most efficient representation of visual data.< >
An approach to visual sampling and reconstruction motivated by concepts from numerical grid generation is presented. Adaptive meshes that can nonuniformly sample and reconstruct intensity and range data are presented....
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ISBN:
(纸本)0818621486
An approach to visual sampling and reconstruction motivated by concepts from numerical grid generation is presented. Adaptive meshes that can nonuniformly sample and reconstruct intensity and range data are presented. Adaptive meshes are dynamic models which are assembled by interconnecting nodal masses with adjustable springs. Acting as mobile sampling sites, the nodes observe properties of the input data, such as intensities, depths, gradients, and curvatures. Based on these nodal observations, the springs automatically adjust their stiffnesses so as to distribute the available degrees of freedom of the reconstructed model in accordance with the local complexity of the input data. The adaptive mesh algorithm runs at interactive rates with continuous 3-D display on a graphics workstation. It is applied to the adaptive sampling and reconstruction of images and surfaces.
Summary form only give. Teleological modeling, a developing approach for creating abstractions and mathematical representations of physically realistic time-dependent objects, is described. In this approach, geometric...
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ISBN:
(纸本)0818621486
Summary form only give. Teleological modeling, a developing approach for creating abstractions and mathematical representations of physically realistic time-dependent objects, is described. In this approach, geometric constraint-properties, mechanical properties of objects, the parameters representing an object, and the control of the object are incorporated into a single conceptual framework. A teleological model incorporates time-dependent goals of behavior of purpose as the primary abstraction and representation of what the object is. A teleological implementation takes a geometrically incomplete specification of the motion, position, and shape of an object, and produces a geometrically complete description of the object's shape and behavior as a function of time. Teleological modeling techniques may be suitable for consideration in computer vision algorithms by extending the current notions about how to make mathematical representations of objects. Teleological descriptions can produce compact representations for many of the physically derivable quantities controlling the shapes, combining-operations, and constraints which govern the formation and motion of objects.
A unified framework for object description and correspondence in range images is proposed. This is based on modeling the ambiguities with a dynamic system at every level of hierarchy. The critical issue in object desc...
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ISBN:
(纸本)0818621486
A unified framework for object description and correspondence in range images is proposed. This is based on modeling the ambiguities with a dynamic system at every level of hierarchy. The critical issue in object description is boundary completion. The authors show how this step can be modeled as the interaction of long and short term variables operating on partial contours, represented by parametric splines. In a sense, this network operates on an evolutionary basis where boundary completion is modeled as a synergistic process, and mutation is modeled as differential decay. Once reliable surface features are extracted, the same framework, with appropriate constraints, can find the corresponding surfaces and compute the transformation.
The problem of measuring the motion of deformable objects from image sequences is addressed. The approach is based upon modeling the overall boundary of the object as a deformable contour and then tracking local segme...
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ISBN:
(纸本)0818621486
The problem of measuring the motion of deformable objects from image sequences is addressed. The approach is based upon modeling the overall boundary of the object as a deformable contour and then tracking local segments of the contour through the temporal sequence. Motion computation involves first matching the local segments between pairs of contours by minimizing the deformation between the segments using a measure of bending energy. Results from the match process are incorporated into an optimization functional, along with a general smoothness term, whose local minimum results in a smooth flow field that is consistent with the match data. The computation is performed for all pairs of frames in the temporal sequence, resulting in a composite flow field over the entire sequence. The technique is applied to synthetic contour sequences and the problem of tracking left ventricular (LV) endocardial motion from medical image sequences.
A novel nonlinear operator for edge detection based on the principles of visual perception is presented. Due to the use of information from an image segmentation process, this operator possesses both local and global ...
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ISBN:
(纸本)0780302168
A novel nonlinear operator for edge detection based on the principles of visual perception is presented. Due to the use of information from an image segmentation process, this operator possesses both local and global adaptability. Experiments over a set of low-contrast photographs show that, compared to some linear and shift-invariant operators, the detector can result in an entropy increase of the edge strength and can match human performance quite well.
The authors present a new template-matching algorithm with good recognition performance. However, this new algorithm exhibits a complex, four-dimensional, wavefront architecture. Thus, for VLSI implementation, reduced...
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ISBN:
(纸本)0818690895
The authors present a new template-matching algorithm with good recognition performance. However, this new algorithm exhibits a complex, four-dimensional, wavefront architecture. Thus, for VLSI implementation, reduced architectures with fewer connections and processors need to be derived. For this purpose, the authors develop a systematic reduction methodology to manually map wavefront computations from high-dimension to low-dimension. This methodology consists of seven steps. Based on this methodology, the authors derive several two-dimensional architectures which are suitable for VLSI implementation for the new template-matching algorithm and have simulated one of the architectures by using the Intel Hypercube Machine iPSC/2.
Summary form only given. Object-oriented recogniton and tracking of lymphocytes has been studied and implemented on a Tracor Northern 8502 image analysis system. Fuzzy sets and fuzzy languages are applied in the recog...
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ISBN:
(纸本)0780302168
Summary form only given. Object-oriented recogniton and tracking of lymphocytes has been studied and implemented on a Tracor Northern 8502 image analysis system. Fuzzy sets and fuzzy languages are applied in the recognitionprocess. In tracking, the intersection of two successive frames is computed. Both the center of mass and the area are used. Various ways to manage uncertainty are also investigated. The results may be applied to other types of cells.
The problem of navigating a robot vehicle which on unstructured roads that have no lane markings, may have degraded surfaces and edges, and may be partially obscured by strong shadows is addressed. These conditions ca...
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ISBN:
(纸本)081862163X
The problem of navigating a robot vehicle which on unstructured roads that have no lane markings, may have degraded surfaces and edges, and may be partially obscured by strong shadows is addressed. These conditions cause many road following systems to fail. The authors have built a system, UNSCARF, which is based on patternrecognition techniques, for successfully navigating on a variety of unstructured roads. UNSCARF does not need a road location prediction to find the location of the road;therefore, UNSCARF can be used as a bootstrapping system. UNSCARF uses a clustering technique to group pixels with similar colors and locations. UNSCARF then matches models of road shape to locate the roads in the image. These methods are more robust in noisy conditions than other road interpretation techniques. UNSCARF has been integrated into a navigation system that has successfully driven a test vehicle in many types of weather conditions.
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