A polynomial time algorithm is presented (pruned correspondence search, PCS) with good average case complexity for solving a wide class of geometric maximal matching problems, including the problem of recognizing 3-D ...
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A polynomial time algorithm is presented (pruned correspondence search, PCS) with good average case complexity for solving a wide class of geometric maximal matching problems, including the problem of recognizing 3-D objects from a single 2-D image. The PCS algorithm is connected with the geometry of the underlying recognition problem only through calls to a verification algorithm. Efficient verification algorithms are given for the case of affine transformations among vector spaces and for the case of rigid 2-D and 3-D transformations with scale. Among the known algorithms that solve the bounded error recognition problem exactly and completely, the PCS algorithm currently has the lowest complexity. Some preliminary experiments suggest that PCS is a practical algorithm.< >
Aspect-ratio is a fundamental parameter of an imaging system. It determines the extent of nonuniformity in sampling. Video signals guarantee a one-to-one match between the camera lines and the lines in the image buffe...
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Aspect-ratio is a fundamental parameter of an imaging system. It determines the extent of nonuniformity in sampling. Video signals guarantee a one-to-one match between the camera lines and the lines in the image buffer. The horizontal arrangement of pixels, however. undergoes a resampling due to the digitization process. The vertical spacing between lines is given by the vertical distance of the photo elements on the sensor array. The relationship between the vertical and horizontal spacing is determined by the aspect-ratio. The author proposes a technique that uses power spectrum of the image of two sets of parallel lines to determine the aspect-ratio of the system.< >
An early-processing.algorithm to extract motion information from closely sampled image sequences is presented. This method outputs dense displacement field, based on the extraction of strips in slices taken from the i...
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An early-processing.algorithm to extract motion information from closely sampled image sequences is presented. This method outputs dense displacement field, based on the extraction of strips in slices taken from the image volume along the temporal dimension. The extracted strips provide estimates of the velocity component along the slice orientation. Because of the high sampling rate, the motion is assumed to be piecewisely translational. A voting scheme to estimate the position of FOE while extracting strips is proposed. The true velocity can then be calculated. Results on several real image sequences and a promising speedup from the parallel implementation on the Connection Machine are presented.< >
A multidimensional edge model is established and a first-order estimation for multidimensional edge profiles is proposed. An optimal edge location detection algorithm is developed. The advantages of the algorithm are ...
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A multidimensional edge model is established and a first-order estimation for multidimensional edge profiles is proposed. An optimal edge location detection algorithm is developed. The advantages of the algorithm are that (1) it has little dependence on assumptions of edge models, noise models, or smoothing filters, (2) it has better abilities for detecting very weak edges and making less edge orientation errors than other edge detectors, (3) it can handle corners and complicated multidimensional image structures, and (4) it detects different edge types at the same time.< >
A robust approach to recovery of shape from shading information is presented. Assuming uniform albedo and Lambertian surface for the imaging model, methods are presented for the estimation of illuminant direction and ...
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A robust approach to recovery of shape from shading information is presented. Assuming uniform albedo and Lambertian surface for the imaging model, methods are presented for the estimation of illuminant direction and surface albedo. The illuminant azimuth is estimated by averaging local estimates. The illuminant elevation and surface albedo are estimated from image statistics. Using the estimated reflectance map parameters, the surface shape is computed using a procedure that implements the smoothness constraint by enforcing the gradients of reconstructed intensity to be close to the gradients of the input image. Typical results on real images are given to illustrate the usefulness of this approach.< >
Detection and thresholding using a stochastic approach is discussed. A general form of detectors which includes a number of well-known detectors as special cases is discussed. Thresholding is indispensable to eliminat...
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Detection and thresholding using a stochastic approach is discussed. A general form of detectors which includes a number of well-known detectors as special cases is discussed. Thresholding is indispensable to eliminate spurious responses from the detection process. The authors propose a weighted thresholding, which is designed to cope with a variety of anomalies. The analysis and experimental results on real images show that intelligent thresholding methods can make a significant difference for discontinuity detection.< >
A hierarchical stereo system is described that uses structural descriptions up to the surface level. Surface descriptions are computed from monocular images, by using a perceptual grouping technique. Occlusion can be ...
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A hierarchical stereo system is described that uses structural descriptions up to the surface level. Surface descriptions are computed from monocular images, by using a perceptual grouping technique. Occlusion can be a major problem in stereo analysis and is often not treated explicitly. An analysis is presented of occlusion effects in stereo, and it is shown how structural descriptions can be used to deal with them. Experimental results are given for scenes with curved objects and significant occlusions.< >
A linear generalized Hough transform (LIGHT) in which a linear numeric pattern is used to replace the single peak in the original generalized Hough transform (GHT) is presented. The LIGHT is more capable of detecting ...
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A linear generalized Hough transform (LIGHT) in which a linear numeric pattern is used to replace the single peak in the original generalized Hough transform (GHT) is presented. The LIGHT is more capable of detecting partially occluded objects. Moreover, it is well-suited for parallelization, especially on SIMD array processors. Several sequential and parallel LIGHT algorithms have been developed. Preliminary results for parallel implementation were obtained from and SIMD one-dimensional array processor (the AIS-4000 vision processor with 512 processing.elements).< >
In a binocular camera system moving through the environment, it is possible to obtain a three-dimensional field of vectors, where each vector is parallel, to the actual inducing 3-D motion of an imaged point (relative...
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In a binocular camera system moving through the environment, it is possible to obtain a three-dimensional field of vectors, where each vector is parallel, to the actual inducing 3-D motion of an imaged point (relative to the moving camera), and scaled in magnitude by the depth of that point. The authors derive this 3-D vector field (the p-field), discuss its computation from the image quantities of optic flow and disparity, and examine its behavior for specific cases of motion as well as for general motion. They present experimental results in computing this vector field and discuss issues related to the determination of the motion parameters from it. The results are demonstrated on synthetic and real data.< >
The authors solve the stereo correspondence problem in uncalibrated domains using extended edge contours as a source of primitives, as opposed to traditional point-based algorithms. This work represents a novel approa...
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The authors solve the stereo correspondence problem in uncalibrated domains using extended edge contours as a source of primitives, as opposed to traditional point-based algorithms. This work represents a novel approach to implementation of the structural stereopsis concept of K.L. Boyr and A.C. Kak (1988), in particular with regard to speed. Judiciously exploiting the contiguity relation among primitives, correspondence solutions without prior knowledge of the epipolar condition for feature-rich stereopairs, previously requiring several days of processing.by the Boyer and Kak algorithm are now acquired in tens of seconds on the same equipment.< >
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