Grimson, William Eric LeifurOverview
Publication Timeline
Most widely held works by
William Eric Leifur Grimson
AI in the 1980s and beyond : an MIT survey
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Book
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10 editions published between 1987 and 1989 in English and held by 782 WorldCat member libraries worldwide
From images to surfaces : a computational study of the human early visual system
by William Eric Leifur Grimson
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Book
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10 editions published between 1981 and 1986 in English and held by 453 WorldCat member libraries worldwide
Object recognition by computer : the role of geometric constraints
by William Eric Leifur Grimson
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Book
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5 editions published in 1990 in English and held by 371 WorldCat member libraries worldwide
A computer implementation of a theory of human stereo vision
by William Eric Leifur Grimson
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Book
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2 editions published between 1980 and 1981 in English and held by 10 WorldCat member libraries worldwide Recently, Marr and Poggio (1979) presented a theory of human stereo vision. An implementation of that theory is presented, and consists of five steps: (1) The left and right images are each filtered with masks of four sizes that increase with eccentricity; the shape of these masks is given by the laplacian of a gaussian function. (2) Zerocrossings in the filtered images are found along horizontal scan lines. (3) For each mask size, matching takes place between zerocrossings of the same sign and roughly the same orientation in the two images, for a range of disparities up to about the width of the mask's central region. Within this disparity range, Marr and Poggio showed that false targets pose only a simple problem. (4) The output of the wide masks can control vergence movements, thus causing small masks to come into correspondence. In this way, the matching process gradually moves from dealing with large disparities at a low resolution to dealing with small disparities at a high resolution. (5) When a correspondence is achieved, it is stored in a dynamic buffer, called the 2 1/2dimensional sketch. To support the sufficiency of the MarrPoggio model of human stereo vision, the implementation was tested on a wide range of stereograms from the human stereopsis literature. The performance of the implementation is illustrated and compared with human perception. As well, statistical assumptions made by Marr and Poggio are supported by comparison with statistics found in practice. Finally, the process of implementing the theory has led to the clarification and refinement of a number of details within the theory; these are discussed in detail. (Author)
CVRMedMRCAS '97 : First Joint Conference Computer Vision, Virtual Reality and Robotics in Medicine and Medical Robotics and ComputerAssisted Surgery, Grenoble, France, March 1997 : proceedings
by Virtual Reality and Robotics in Medicine and Medical Robotics and Computer Assisted Surgery Joint Conference Computer Vision
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Book
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1 edition published in 1997 in English and held by 8 WorldCat member libraries worldwide
AI in the 1980's and beyond edited by W Eric L Grimson and Ramesh S Patil
by William Eric Leifur Grimson
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Book
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3 editions published in 1987 in English and held by 6 WorldCat member libraries worldwide
On the recognition of curved objects
by William Eric Leifur Grimson
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Book
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1 edition published in 1987 in English and held by 5 WorldCat member libraries worldwide Determining the identity and pose of occluded objects from noisy data is a critical part of a system's intelligent interaction with an unstructured environment. Previous work has shown that local measurements of the position and surface orientation of small patches of an object's surface may be used in a constrained search process to solve this problem for the case of rigid polygonal objects using twodimensional sensory data, or rigid polyhedral objects using threedimensional data. This note extends the recognition system to deal with the problem of recognizing and locating curved objects. The extension is done in two dimensions, and applies to the recognition of twodimensional objects from twodimensional data, or to the recognition of threedimensional objects in stable positions from twodimensional data
Annotated production systems : a model for skill acquisition
by Ira P Goldstein
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Book
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2 editions published in 1977 in English and held by 5 WorldCat member libraries worldwide APS provide a procedural model for skill acquisition by augmenting a production model of the skill with formal commentary describing plans, bugs, and interrelationships between various productions. This commentary supports processes of efficient interpretation, selfdebugging and selfimprovement. The theory of annotated productions is developed by analyzing the skill of attitude instrument flying. An annotated production interpreter has been written that executes skill models which control a flight simulator. (Author)
Special issue on interpretation of 3D scenes
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Book
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2 editions published in 1992 in English and held by 5 WorldCat member libraries worldwide
The effect of indexing on the complexity of object recognition
by William Eric Leifur Grimson
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Book
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2 editions published in 1990 in English and held by 4 WorldCat member libraries worldwide
The combinatorics of heuristic search termination for object recognition in cluttered environments
by William Eric Leifur Grimson
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Book
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2 editions published in 1989 in English and held by 4 WorldCat member libraries worldwide Many current recognition systems use constrained search to locate objects in cluttered environments. Earlier analysis of one class of methods has shown that the expected amount of search is quadratic in the number of model and date features, if all the data is known to come from a single object, but is exponential when spurious data is included. To overcome this, many methods terminate search once an interpretation that is'good enough' is found. This paper formally examines the combinations of this approach, showing that choosing correct termination procedures can dramatically reduce the search. In particular, conditions are provided for the object model and the scene clutter such that the expected search is polynomial. The analytic results are shown to be in agreement with empirical data for cluttered object recognition
Differential geometry, surface patches and convergence methods
by William Eric Leifur Grimson
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Book
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2 editions published in 1979 in English and held by 4 WorldCat member libraries worldwide The problem of constructing a surface from the information provided by the MarrPoggio theory of human stereo vision is investigated. It is argued that not only does this theory provide explicit boundary conditions at certain points in the image, but that the imaging process also provides implicit conditions on all other points in the image. This argument is used to derive conditions on possible algorithms for computing the surface. Additional constraining principles are applied to the problem; specifically that the process be performable by a localsupport parallel network. Some mathematical tools, differential geometry, Coons surface patches and iterative methods of convergence, relevant to the problem of constructing the surface are outlined. Specific methods for actually computing the surface are examined. (Author)
Recognition and localization of overlapping parts from sparse data
by William Eric Leifur Grimson
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Book
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1 edition published in 1985 in English and held by 4 WorldCat member libraries worldwide Abstract: "This paper discusses how sparse local measurements of positions and surface normals may be used to identify and locate overlapping objects. The objects are modeled as polyhedra (or polygons) having up to six degrees of positional freedom relative to the sensors. The approach operates by examining all hypotheses about pairings between sensed data object surfaces and efficiently discarding inconsistent ones by using local constraints on: distances between faces, angles between face normals, and angles (relative to the surface normals) of vectors between sensed points
Binocular shading and visual surface reconstruction
by William Eric Leifur Grimson
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Book
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3 editions published between 1982 and 1983 in English and held by 4 WorldCat member libraries worldwide Zerocrossing or featurepoint based stereo algorithms can, by definition, determine explicit depth information only at particular points in the image. To compute a complete surface description, this sparse depth map must be interpolated. A computational theory of this interpolation or reconstruction process, based on a surface consistency constraint, has previously been proposed. In order to provide stronger boundary conditions for the interpolation process, other visual cues to surface shape are examined in this paper. In particular, it is shown that, in principle, shading information from the two views can be used to determine the orientation of the surface normal along the featurepoint contours, as well as the parameters of the reflective properties of the surface material. The numerical stability of the resulting equations is also examined. (Author)
The perception of subjective surfaces
by Michael Brady
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Book
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2 editions published in 1981 in English and held by 4 WorldCat member libraries worldwide It is proposed that subjective contours are an artifact of the perception of natural three dimensional surfaces. A recent theory of surface interpolation implies that 'subjective surfaces' are constructed in the visual system by interpolation between threedimensional values arising from interpretation of a variety of surface cues. We show that subjective surfaces can take any form, including singly and doubly curved surfaces, as well as the commonly discussed frontoparallel planes
Artificial intelligence in the 1980s and beyond : an MIT survey
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Book
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1 edition published in 1987 in English and held by 4 WorldCat member libraries worldwide
On the sensitivity of the Hough transform for object recognition
by William Eric Leifur Grimson
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Book
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2 editions published in 1988 in English and held by 4 WorldCat member libraries worldwide Object recognition from sensory data involves, in part, determining the pose of a model with respect to a scene. A common method for finding an object's pose is the generalized Hough transform, which accumulates evidence for possible coordinate transformations in a parameter space whose axes are the quantized transformation parameters. Large clusters of similar transformations in that space are taken as evidence of a correct match. This article provides a theoretical analysis of the behavior of such methods. The authors derive bounds on the set of transformations consistent with each pairing of data and model features, in the presence of noise and occlusion in the image. They also provide bounds on the likelihood of false peaks in the parameter space, as a function of noise, occlusion, and tessellation effects. It is argued that blithely applying such methods to complex recognition tasks is a risky proposition, as the probability of false positives can be very high. Keywords: Two dimensional noise analysis. (kr)
Recognizing 3D objects from 2D images : an error analysis
by William Eric Leifur Grimson
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Book
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1 edition published in 1992 in English and held by 4 WorldCat member libraries worldwide Abstract: "Many recent object recognition systems use a small number of pairings of data and model features to compute the 3D transformation from a model coordinate frame into the sensor coordinate system. In the case of perfect image data, these systems seem to work well. With uncertain image data, however, the performance of such methods is less well understood. In this paper, we examine the effects of two dimensional sensor uncertainty on the computation of threedimensional model transformations. We use this analysis to bound the uncertainty in the transformation parameters, as well as the uncertainty associated with applying the transformation to map other model features into the image. We also examine the effects of the transformation uncertainty on the effectiveness of recognition methods."
On the verification of hypothesized matches in modelbased recognition
by William Eric Leifur Grimson
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Book
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2 editions published in 1989 in English and held by 4 WorldCat member libraries worldwide In modelbased recognition a number of ad hoc techniques are used to decide whether or not a match of data to a model is correct. Generally an empirically determined threshold is placed on the fraction of model features that must be matched. In this paper we present a more rigorous approach in which the conditions under which to accept a matched are derived based on fundamental grounds. We obtain an expression that relates the probability of a matched occuring at random to the reaction of a model features that are accounted for by the match. This expression is a function of the number of model features, the number of image features, and a bound on the degree on the degree of sensor noise. One implication of our analysis is that a proper threshold for matching must vary with the number of model and data features. Thus, it is important to be able to set the threshold as a function of a particular matching problem, rather than setting a single threshold as a function of a particular matching problem, rather than setting a single threshold based on experimentation. We analyze some existing recognition systems and find that our method yields threshold similiar to the ones were determined empirically for these systems, providing evidence of the validity of the technique. (KR)
The combinatorics of object recognition in cluttered environments using constrained search
by William Eric Leifur Grimson
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Book
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1 edition published in 1988 in English and held by 4 WorldCat member libraries worldwide When clustering techniques such as the Hough transform are used to isolate likely subspaces of the search space, empirical performance in cluttered scenes improves considerably. In this paper we establish formal bounds on the combinatorics of this approach. Under some simple assumptions, we show that the expected complexity of recognizing isolated objects is quadratic in the number of model and sensory fragments, but that the expected complexity of recognizing objects in cluttered environments is exponential in the size of the correct interpretation. We also provide formal bounds on the efficacy of using the Hough transform to preselect likely subspaces, showing that the problem remains exponential, but that in practical terms, the size of the problem is significantly decreased more
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Artificial intelligence Binocular visionData processing Computer graphics Computer vision Computer vision in medicine Heuristic programming Image analysis Image processing Image processingDigital techniques Mappings (Mathematics) Optical data processing Pattern perception Pattern recognition systems Robotics in medicine Robots, Industrial Search theory SurgeryData processing Virtual reality in medicine Vision Visual perception Visual perceptionMathematical models

Alternative Names
Grimson, W. Eric L.
Grimson, W. Eric L. (William Eric Leifur)
Leifur Grimson William Eric
グリムソン, W. エリック・L
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