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.
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.
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.
A spatiotemporal (ST) image cube, created by stacking a temporally dense sequence of images together, is a temporally coherent data representation. Using ST surface flow, i.e., the extension of optical flow to ST surf...
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ISBN:
(纸本)0818621486
A spatiotemporal (ST) image cube, created by stacking a temporally dense sequence of images together, is a temporally coherent data representation. Using ST surface flow, i.e., the extension of optical flow to ST surfaces, it is shown how ST flow curves can be recovered and then used to detect groups of flow curves such that each group represents a single object or surface in the scene undergoing motion. The algorithm forms clusters of similar flow curves and is based on constraints called the temporal uniqueness constraints. First, a point in an image can only move to at most one point in the next image. Second, a point in an image can come from at most one point in the previous image. When these constraints are violated, or it appears that they are violated, occlusion or disocclusion has occurred and therefore can also be detected. Successful grouping of coherent regions of the ST cube for two gray-level image sequences is shown.
The major direct solutions to the three-point perspective pose estimation problems are reviewed from a unified perspective. The numerical stability of these three-point perspective solutions are discussed. It is shown...
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ISBN:
(纸本)0818621486
The major direct solutions to the three-point perspective pose estimation problems are reviewed from a unified perspective. The numerical stability of these three-point perspective solutions are discussed. It is shown that even in cases where the solution is not near the geometric unstable region considerable care must be exercised in the calculation. Depending on the order of the substitutions utilized, the relative error can change over a thousand to one. This difference is due entirely to the way the calculations are performed and not to any geometric structural instability of any problem instance. An analytical method is presented which produces a numerically stable calculation.
A 3-D deformable model is introduced which evolves in true 3-D images, under the action of internal forces (describing some elasticity properties of the surface), and external forces attracting the surface toward some...
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ISBN:
(纸本)0818621486
A 3-D deformable model is introduced which evolves in true 3-D images, under the action of internal forces (describing some elasticity properties of the surface), and external forces attracting the surface toward some detected edgels. The formalism leads to the minimization of an energy which is expressed as a functional. The authors use a variational approach and a finite-element method to express the surface in a discrete basis of continuous functions. This leads to a reduced computational complexity and a better numerical stability. The power of the approach to segment 3-D images is demonstrated by a set of experimental results on various complex medical 3-D images.
An optimal deformable contour approximation algorithm using a cardinal-form piecewise cubic spline (PCS) curve representation is presented. The approximation is optimal in the sense of least square errors in both loca...
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ISBN:
(纸本)0818621486
An optimal deformable contour approximation algorithm using a cardinal-form piecewise cubic spline (PCS) curve representation is presented. The approximation is optimal in the sense of least square errors in both location and orientation. The knots are set automatically at high curvature positions. The sample data are generated by a robust edge fragment detection algorithm which is optimal in the sense of a weighted absolute error. An initial contour placement algorithm uses a penalized maximum likelihood algorithm to group the edge fragments together for an initial contour. A controlled deformable contour algorithm refines the initial contour to cover meaningful edge features.
A noniterative approach to determine displacement vector fields with discontinuities is described. In order to overcome the limitations of current methods, the problem is regarded as a general modeling problem. From t...
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ISBN:
(纸本)0818621486
A noniterative approach to determine displacement vector fields with discontinuities is described. In order to overcome the limitations of current methods, the problem is regarded as a general modeling problem. From this point of view the imaging field consists of a set of regions with common properties and their boundaries. The strategy proposed is an analysis of consistency of the displacement estimators between different levels of regularization. This gives local but noisy evidence of possible model boundaries at multiple scales. With the two constraints of continuous lines of discontinuities and the spatial coincidence assumption, consistent boundary evidence is found. Based on this combined evidence the model is updated so that it describes homogeneous regions with sharp discontinuities.
An approach for determining the location and orientation of a camera mounted on an ALV (autonomous land vehicle) is proposed. The authors choose the road boundaries and the objects with vertical edges to be the calibr...
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ISBN:
(纸本)0818621486
An approach for determining the location and orientation of a camera mounted on an ALV (autonomous land vehicle) is proposed. The authors choose the road boundaries and the objects with vertical edges to be the calibration objects. During the calibration process, the ALV is supposed to move with pure translation. The camera models are derived by using two or three images under the assumptions that the height of the camera and the distance during taking images are known in advance. The tilt and swing angles can be computed from the first image. The pan angle can then be derived by using the projections of vertical edges in three images. If the angle between the moving direction of the ALV and the direction of road boundaries is large enough, two images are enough to find the pan angle. Two translational parameters can be found by employing the projections of vertical edges in two or three images.
A unified theoretical framework for motion transparency and motion boundaries by devising fundamental constraint equations of multiple optical flow is proposed. This framework can handle flow discontinuities at motion...
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ISBN:
(纸本)0818621486
A unified theoretical framework for motion transparency and motion boundaries by devising fundamental constraint equations of multiple optical flow is proposed. This framework can handle flow discontinuities at motion boundaries as well as flow multiplicities due to transparency of objects in a unified manner. The constraint equations are formulated by a composition of homogeneously parametrized differential operators on the space-time image. Fitting algorithms for the constraints which result in eigensystem analyses are described. To determine the number of flows, the authors use the margin energy, a measure of goodness of fit which is the difference between the first and the second lower eigenenergy of the eigensystem. They also hypothesize a criterion for multiplicity. The measure and the criterion are derived from the analogy of quantum mechanics. It is demonstrated that the margin energy can determine the transparency and discontinuities of the flow field as regions of more than one flow.
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