A method is described that generates 3D descriptions of arbitrarily-curved surfaces of physical objects by imageprocessing.and photogrammetric techniques. A surface that is to be described is illuminated by a pattern...
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A method is described that generates 3D descriptions of arbitrarily-curved surfaces of physical objects by imageprocessing.and photogrammetric techniques. A surface that is to be described is illuminated by a pattern of lines. The 3D shape of the surface causes the pattern to be distorted. The illuminated parts of the surface are photographed from two or more vantage points and the resulting images are digitized. The 2D perspective projection of the surface-distorted line pattern is extracted from each digitized image. Camera calibration marks are also extracted and the position of the camera is determined for each image. Two or more projections of the line pattern are then matched and the line pattern projected on the surface is reconstructed into 3D.
proceedings include 55 papers that deal with the computer application in structural analysis and design;construction methods and equipment;municipal engineering;hydrotechnical construction and hydraulic structure;and ...
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proceedings include 55 papers that deal with the computer application in structural analysis and design;construction methods and equipment;municipal engineering;hydrotechnical construction and hydraulic structure;and buildings design and construction. Some papers are presented in French. Thirteen papers are indexed separately.
This study presents a suboptimal boundary estimation algorithm for noisy images which is based upon an optimal maximum likelihood problem formulation. Both the maximum likelihood formulation and the resulting algorith...
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This study presents a suboptimal boundary estimation algorithm for noisy images which is based upon an optimal maximum likelihood problem formulation. Both the maximum likelihood formulation and the resulting algorithm are described in detail, and computational results are given. In addition, the potential power of the likelihood formulation is demonstrated through the presentation of three simple but insightful analyses of algorithm performance.
This study deals with an optimization technique applied to the problem of stochastic labeling. The authors propose a definition of a global criterion on a set of objects to be labeled that combines both ambiguity and ...
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This study deals with an optimization technique applied to the problem of stochastic labeling. The authors propose a definition of a global criterion on a set of objects to be labeled that combines both ambiguity and consistency with adjustable weights. A projected gradient algorithm is developed to minimize the criterion. Results are shown on a toy example and on the edge detection problem. Comparisons are made with relaxation labeling techniques.
The growing use and analysis of images by computer presents many problems in managing images and image information. Solutions to these problems can be specific, with file structures to represent the needed information...
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The growing use and analysis of images by computer presents many problems in managing images and image information. Solutions to these problems can be specific, with file structures to represent the needed information, or general, such as a general Data Base Management System. A presentation is made of a compromise solution, a Raster image File Format (RIFF), that uses image file headers for the storage of specific image format information, as well as very general Name-Value pair information. This latter structure enables varying kinds of information to be represented, including links to other kinds of image data structures as the need arises.
A description is given of a technique for generating a skeleton of a ribbon-like object using sequential data for all or part of the boundary. It shows how one may use local geometric information derived from the cont...
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A description is given of a technique for generating a skeleton of a ribbon-like object using sequential data for all or part of the boundary. It shows how one may use local geometric information derived from the contour to aid in the generation of a skeleton. For contours or curves of length n, this may be accomplished with a computation time of order n, while previous algorithms generally require order n**2 and require a two-dimensional matrix for their working representation.
An examination is made of the fuzzy approach of E. H. Ruspini to the problem of pattern classification. The problem of classification as that of estimating a partition of the data to be classified is presented. An alg...
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An examination is made of the fuzzy approach of E. H. Ruspini to the problem of pattern classification. The problem of classification as that of estimating a partition of the data to be classified is presented. An algorithm is presented for classifying data issued from a Gaussian environment;the fundamental tool of this algorithm is the use of numerical filters for estimating a set of parameters which characterize each class. This algorithm has been applied to the recognition of the components of a mixture of Normal distributions.
Consideration is given to a class of patterns which are subject to the action of a group of transformations. The author is particularly concerned with the existence of measurements or features which are invariant with...
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Consideration is given to a class of patterns which are subject to the action of a group of transformations. The author is particularly concerned with the existence of measurements or features which are invariant with respect to transformation. A concept of relative invariance is also introduced and explored in depth. In a very general sense, it is shown that every invariant (and relative invariant) is a suitable average over the relevant group of transformations. Finally, invariant means of bounded functions are used to explore existence of pattern invariants. Suggestions for further research are also given.
A new technique is described fast ″scan-along″ computation of piecewise linear approximations of digital curves in 2-space. Our method is derived from earlier work on the theory of minimum-perimeter polygonal approx...
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A new technique is described fast ″scan-along″ computation of piecewise linear approximations of digital curves in 2-space. Our method is derived from earlier work on the theory of minimum-perimeter polygonal approximations of digitized closed curves. It is demonstrated that the specialization of this technique to the cases where the error is measured as a) the largest Hausdorff-Euclidean distance between the approximation and the given digitized curve, and b) the largest vertical distance between the approximation and a corresponding point on the given digitized curve.
A new class of texture features based on the joint occurrences of gray levels at points defined relative to edge maxima are introduced. These features are compared with previous types of cooccurrence-based features, a...
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A new class of texture features based on the joint occurrences of gray levels at points defined relative to edge maxima are introduced. These features are compared with previous types of cooccurrence-based features, and experimental results are presented indicating that the new features should be useful for texture classification. In the second part, three simple methods of extracting texture primitives are compared. It appears that the simplest of these, thresholding at a fixed percentile, yields primitives that are quite effective in texture discrimination.
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