A simple MAP model-matching criteron that captures important aspects of recognition in controlled situations is described. A detailed metrical object model is assumed. A probabilistic model of image features is combin...
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ISBN:
(纸本)0818621486
A simple MAP model-matching criteron that captures important aspects of recognition in controlled situations is described. A detailed metrical object model is assumed. A probabilistic model of image features is combined with a simple prior on both the pose and the feature interpretations to yield a mixed objective function. The parameters that appear in the probabilistic models can be derived from images in the application domain. By extremizing the objective function, an optimal matching between model and image feature results. Within this framework, good models of feature uncertainty allow for robustness despite inaccuracy in feature detection. In addition, the relative likelihood of features arising from either the object or the background can be evaluated in a rational way. The objective function provides a simple and uniform means of evaluating match and pose hypotheses. Several linear projection and feature models are discussed. An experimental implementation of MAP model matching, among features derived from low-resolution edge images, is described.
A curvature-based approach to estimating nonrigid deformation of moving surfaces is described. conformal motion can characterized by stretching of the surface. At each point this stretching is equal in all directions,...
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ISBN:
(纸本)0818621486
A curvature-based approach to estimating nonrigid deformation of moving surfaces is described. conformal motion can characterized by stretching of the surface. At each point this stretching is equal in all directions, but is different for different points. This stretching function can be defined as an additional (with global translation and rotation) motion parameter. An algorithm for local stretching recovery from Gaussian curvature based on polynomial approximations of the stretching function is presented. These methods require point correspondences between time frames, but not the complete knowledge of nonrigid transformation.
Multichannel filtering techniques are presented for obtaining both region- and edge-based segmentations of textured images. The channels are represented by a bank of even-symmetric Gabor filters that near uniformly co...
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ISBN:
(纸本)0818621486
Multichannel filtering techniques are presented for obtaining both region- and edge-based segmentations of textured images. The channels are represented by a bank of even-symmetric Gabor filters that near uniformly covers the spatial-frequency domain. Feature images are obtained by subjecting each (selected) filtered image to a nonlinear transformation and computing a measure of energy around each pixel. Region-based segmentations are obtained by using a square-error clustering algorithm. Edge-based segmentations are obtained by applying an edge detector to each feature image and combining their magnitude responses. An integrated segmentation technique that combines the strengths of the previous two techniques while eliminating their weaknesses is proposed. The integrated approach is truly unsupervised, since it eliminates the need for knowing the exact number of texture categories in the image.
The authors present techniques with which camera viewpoints can be automatically determined in order to satisfy the generic feature detectability requirements of resolution, focus, and field-of-view. These optical con...
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ISBN:
(纸本)0818621486
The authors present techniques with which camera viewpoints can be automatically determined in order to satisfy the generic feature detectability requirements of resolution, focus, and field-of-view. These optical constraints are characterized analytically for a general thick lens model, and complete viewpoint loci that satisfy these constraints are obtained. The results discussed are useful for automating the vision system design process, as well as for programming the vision system itself. In addition, such planning techniques can also automate robot imaging systems that reconfigure themselves in an intelligent manner in order to optimize imaging quality.
Two patternrecognition algorithms are proposed to detect two types of knots in lumber, lumped and surface knots, using an optical scanner. It is shown that lumped knots can be recognized by a log profile approach and...
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ISBN:
(纸本)0818621486
Two patternrecognition algorithms are proposed to detect two types of knots in lumber, lumped and surface knots, using an optical scanner. It is shown that lumped knots can be recognized by a log profile approach and surface knots can be detected by an imageprocessing approach. A mathematical model for describing the geometry of the knots inside the log based on the surface parameters of the knots is presented. By a log breakdown strategy, the log can be cut into a maximum number of boards with prescribed dimensionalities. The mathematical knot model can be used to predict the locations, sizes, orientations, and shapes of the knots on these boards, whereby their lumber grades can be determined. Summing up the value yields of all the boards gives the value yield of the log. By computing all the possible value yields of the log from different log orientations, one can determine a maximum value yield of a log.
A variety of architectures have been proposed for integrating vision modules into a complete system. An examination of these systems indicates that they either lack analytic/computational tractability or are based on ...
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ISBN:
(纸本)0818621486
A variety of architectures have been proposed for integrating vision modules into a complete system. An examination of these systems indicates that they either lack analytic/computational tractability or are based on restrictive assumptions such as global additivity or sequential, decoupled solution of objectives. The authors introduce a framework of integration which overcomes both of these shortcomings. This proposed model is based on game-theoretic setting in which a correspondance between a vision system and a N-player game is established. The authors demonstrate the power of such a model within a comparative study in the context of a system aimed at delineating 2-D deformable contours from noisy images.
An algorithm for tracking multiple feature positions in a dynamic image sequence is presented. This is achieved using a combination of two trajectory-based methods, with the resulting hybrid algorithm exhibiting the a...
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ISBN:
(纸本)0818621486
An algorithm for tracking multiple feature positions in a dynamic image sequence is presented. This is achieved using a combination of two trajectory-based methods, with the resulting hybrid algorithm exhibiting the advantages of both. An optimizing exchange algorithm is described which enables short feature paths to be tracked without prior knowledge of the motion being studied. The resulting partial trajectories are then used to initialize a fast predictor algorithm which is capable of rapidly tracking multiple feature paths. As this predictor algorithm becomes tuned to the feature positions being tracked, it is shown how the location of occluded or poorly detected features can be predicted. The results of applying this tracking algorithm to data obtained from real-world scenes are then presented.
The problem of matching a model consisting of the point features of a flat object to point features found in an image that contains the object in an arbitrary three-dimensional pose is addressed. Once three points are...
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ISBN:
(纸本)0818621486
The problem of matching a model consisting of the point features of a flat object to point features found in an image that contains the object in an arbitrary three-dimensional pose is addressed. Once three points are matched, it is possible to determine the pose of the object. Assuming bounded sensing error, the author presents a solution to the problem of determining the range of possible locations in the image at which any additional model points may appear. This solution leads to an algorithm for determining the largest possible matching between image and model features that includes this initial hypothesis. He has implemented a close approximation to this algorithm, which is O(nmΕ6), where n is the number of image points, m is the number of model points, and Ε is the maximum sensing error. This algorithm is compared to existing methods, and it is shown that it produces more accurate results.
Two corner detectors are presented, one of which works by testing similarity of image patches along the contour direction to detect curves in the image contour, and the other of which uses direct estimation image curv...
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ISBN:
(纸本)0818621486
Two corner detectors are presented, one of which works by testing similarity of image patches along the contour direction to detect curves in the image contour, and the other of which uses direct estimation image curvature along the contour direction. The operators are fast, robust to noise, and self-thresholding. An interpretation of the Kitchen-Rosenfeld corner operator is presented which shows that this operator can also be viewed as the second derivative of the image function along the edge direction.
An edge-based trinocular stereovision algorithm is presented. The primitives it works on are cubic B-spline approximations of the 2-D edges. This allows one to deal conveniently with curvature and to extend to some no...
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ISBN:
(纸本)0818621486
An edge-based trinocular stereovision algorithm is presented. The primitives it works on are cubic B-spline approximations of the 2-D edges. This allows one to deal conveniently with curvature and to extend to some non-polyhedral scenes to previous stereo algorithms. To build a matching primitive, the principle of the algorithm is, first, to find a triplet of corresponding points on three splines. This is provided by the bootstrapping part. Second, the algorithm propagates along the three supporting splines to find other matching points. This provides a set of ordered point triplets along these three splines, for which all the matching constraints are verified. This primitive constitutes a trinocular hypothesis. The set of all hypotheses is obtained by propagating from all the point triplets provided by the bootstrapping process. A criterion based on the size of the hypotheses is then used to choose among them a compatible set with respect to the uniqueness constraint. Results of several 3-D reconstructed scenes are shown.
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