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Pattern Analysis and Machine Intelligence, IEEE Transactions on

Issue 4 • Date Apr 1990

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Displaying Results 1 - 8 of 8
  • Modeling light reflection for computer color vision

    Publication Year: 1990 , Page(s): 402 - 409
    Cited by:  Papers (45)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (668 KB)  

    In computer vision applications, analysis of shading information requires a proper model of light reflection from object surfaces. To overcome the shortcoming of the most often used model and to extend the reflection model for computer color vision, an examination is made of the light reflection problem using the bidirectional spectral-reflectance distribution function (BSRDF) to specify both incident- and reflected-beam geometries. It is shown that the product form can still be retained for a polychromatic light source under two lighting conditions: the light source is collimated; or the spectral factor and the geometric factor can be separated for both the light source and the BSRDF of the surface. The reflection model is then applied to the formulation of a neutral-interface-reflection model, which is tested experimentally. The results show the adequacy of this type of model for surfaces of some material compositions, e.g. plastics, plant leaves, painted surfaces, orange peels, and some glossy cloth, but not for others, e.g. colored paper and some ceramics View full abstract»

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  • Shape reconstruction on a varying mesh

    Publication Year: 1990 , Page(s): 345 - 362
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1584 KB)  

    A central class of image understanding problems is concerned with reconstructing a shape from an incomplete data set, such as fitting a surface to (partially) given contours. A new theory for solving such problems is presented. Unlike the current heuristic methods, the method used starts from fundamental principles that should be followed by any reconstruction method, regardless of its mathematical or physical implementation. A mathematical procedure which conforms to these principles is presented. One major advantage of the method is the ability to handle shapes containing both smooth and sharp parts without using thresholds. A sharp variation, such as a corner, requires a high-resolution mesh for adequate representation, while slowly varying sections can be represented with sparser mesh points. Unlike current methods, this procedure fits the surface on a varying mesh. The mesh is constructed automatically to be more dense at parts of the image that have more rapid variation. Analytical examples are given in simple cases, followed by numerical experiments View full abstract»

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  • Coping with discontinuities in computer vision: their detection, classification, and measurement

    Publication Year: 1990 , Page(s): 321 - 344
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1748 KB)  

    The general principles of detection, classification, and measurement of discontinuities are studied. The following issues are discussed: detecting the location of discontinuities; classifying discontinuities by their degrees; measuring the size of discontinuities; and coping with the random noise and designing optimal discontinuity detectors. An algorithm is proposed for discontinuity detection from an input signal S. For degree k discontinuity detection and measurement, a detector (P,Φ) is used, where P is the pattern and Φ is the corresponding filter. If there is a degree k discontinuity at location t0, then in the filter response there is a scaled pattern αP at t0, where α is the size of the discontinuity. This reduces the problem to searching for the scaled pattern in the filter response. A statistical method is proposed for the approximate pattern matching. To cope with the random noise, a study is made of optimal detectors, which minimize the effects of noise View full abstract»

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  • A frequency domain algorithm for multiframe detection and estimation of dim targets

    Publication Year: 1990 , Page(s): 398 - 401
    Cited by:  Papers (51)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (356 KB)  

    An algorithm for detecting moving targets by imaging sensors and estimating their trajectories is proposed. The algorithm is based on directional filtering in the frequency domain, using a bank of filters for all possible target directions. The directional filtering effectively integrates the target signal, resulting in an improved signal-to-noise ratio. Working in the frequency domain facilitates a considerable reduction in computational requirements compared to time-domain algorithms. The algorithm is described in detail, and its false alarm and detection probabilities are analyzed View full abstract»

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  • High-speed triangulation-based 3-D imaging with orthonormal data projections and error detection

    Publication Year: 1990 , Page(s): 409 - 416
    Cited by:  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB)  

    Improvements to the triangulation range-sensing technique are described. The improvements greatly increase the range-data collection rate, while simultaneously providing for improved data integrity and a low-cost implementation. These benefits are achieved by using some unique abilities of the charge-injection-device image sensor. A laser-based investigation system has been built around a personal computer and used to evaluate the effectiveness of the improvements. Range data results are shown for the proposed application of printed-circuit board inspection View full abstract»

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  • An interobject distance measure based on medial axes retrieved from discrete distance maps

    Publication Year: 1990 , Page(s): 390 - 397
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (704 KB)  

    A method that measures the distance between extended objects of nonregular shape is presented. The distance measure is an average of a set of minimal point-to-point distances between the borders of the objects. The set of points is collected with a well-defined criterion based on processing of distance values on a connected medial axis formed between the objects View full abstract»

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  • Reconstructing convex sets from support line measurements

    Publication Year: 1990 , Page(s): 377 - 389
    Cited by:  Papers (17)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1116 KB)  

    Algorithms are proposed for reconstructing convex sets given noisy support line measurements. It is observed that a set of measured support lines may not be consistent with any set in the plane. A theory of consistent support lines which serves as a basis for reconstruction algorithms that take the form of constrained optimization algorithms is developed. The formal statement of the problem and constraints reveals a rich geometry that makes it possible to include prior information about object position and boundary smoothness. The algorithms, which use explicit noise models and prior knowledge, are based on maximum-likelihood and maximum a posteriori estimation principles and are implemented using efficient linear and quadratic programming codes. Experimental results are presented. This research sets the stage for a more general approach to the incorporation of prior information concerning the estimation of object shape View full abstract»

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  • The chain pyramid: hierarchical contour processing

    Publication Year: 1990 , Page(s): 363 - 376
    Cited by:  Papers (13)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1268 KB)  

    A novel hierarchical approach toward fast parallel processing of chain-codable contours is presented. The environment, called the chain pyramid, is similar to a regular nonoverlapping image pyramid structure. The artifacts of contour processing on pyramids are eliminated by a probabilistic allocation algorithm. Building of the chain pyramid is modular, and for different applications new algorithms can be incorporated. Two applications are described: smoothing of multiscale curves and gap bridging in fragmented data. The latter is also employed for the treatment of branch points in the input contours. A preprocessing module allowing the application of the chain pyramid to raw edge data is also described. The chain pyramid makes possible fast, O[log(image-size)], computation of contour representation in discrete scale-space View full abstract»

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The IEEE Transactions on Pattern Analysis and Machine Intelligence (TPAMI) is published monthly. Its editorial board strives to present most important research results in areas within TPAMI's scope.

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Editor-in-Chief
David A. Forsyth
University of Illinois