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31
Photobook: ContentBased Manipulation of Image Databases
, 1995
"... We describe the Photobook system, which is a set of interactive tools for browsing and searching images and image sequences. These query tools differ from those used in standard image databases in that they make direct use of the image content rather than relying on text annotations. Direct search o ..."
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Cited by 526 (0 self)
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We describe the Photobook system, which is a set of interactive tools for browsing and searching images and image sequences. These query tools differ from those used in standard image databases in that they make direct use of the image content rather than relying on text annotations. Direct search on image content is made possible by use of semanticspreserving image compression, which reduces images to a small set of perceptuallysignificant coefficients. We describe three types of Photobook descriptions in detail: one that allows search based on appearance, one that uses 2D shape, and a third that allows search based on textural properties. These image content descriptions can be combined with each other and with textbased descriptions to provide a sophisticated browsing and search capability. In this paper we demonstrate Photobook on databases containing images of people, video keyframes, hand tools, fish, texture swatches, and 3D medical data.
Active Blobs
, 1998
"... A new regionbased approach to nonrigid motion tracking is described. Shape is defined in terms of a deformable triangular mesh that captures object shape plus a color texture map that captures object appearance. Photometric variations are also modeled. Nonrigid shape registration and motion trackin ..."
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Cited by 96 (5 self)
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A new regionbased approach to nonrigid motion tracking is described. Shape is defined in terms of a deformable triangular mesh that captures object shape plus a color texture map that captures object appearance. Photometric variations are also modeled. Nonrigid shape registration and motion tracking are achieved by posing the problem as an energybased, robust minimization procedure. The approach provides robustness to occlusions, wrinkles, shadows, and specular highlights. The formulation is tailored to take advantage of texture mapping hardware available in many workstations, PC's, and game consoles. This enables nonrigid tracking at speeds approaching video rate.
Segmentation of 2D and 3D objects from MRI volume data using constrained elastic deformations of flexible Fourier contour and surface models
, 1996
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Combining point distribution models with shape models based on finite element analysis
 Image and Vision Computing
, 1995
"... This paper describes a method of combining two approaches to modelling flexible objects. Modal Analysis using Finite Element Methods (FEMs) generates a set of vibrational modes for a single shape. Point Distribution Models (PDMs) generate a statistical model of shape and shape variation from a set o ..."
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Cited by 76 (5 self)
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This paper describes a method of combining two approaches to modelling flexible objects. Modal Analysis using Finite Element Methods (FEMs) generates a set of vibrational modes for a single shape. Point Distribution Models (PDMs) generate a statistical model of shape and shape variation from a set of example shapes. A new approach is described which generates vibrational modes when few example shapes are available and changes smoothly to using more statistical modes of variation when a large data set is presented. Results are given for both synthetic and real examples. Experiments using the models for image search show that the combined version performs better than either the PDM or FEM models alone. 1
Statistical Shape Analysis Using Fixed Topology Skeletons: Corpus Callosum Study
 In International Conference on Information Processing in Medical Imaging, LNCS 1613
, 1999
"... . The goal of this work is to develop an approach to shape representation and classification that will allow us to detect and quantify di#erences in shape of anatomical structures due to various disorders. We used a robust version of skeletons for feature extraction and linear discriminant analy ..."
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Cited by 51 (5 self)
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. The goal of this work is to develop an approach to shape representation and classification that will allow us to detect and quantify di#erences in shape of anatomical structures due to various disorders. We used a robust version of skeletons for feature extraction and linear discriminant analysis ( the Fisher linear discriminant and the linear Support Vectors method) for classification. We propose a way to map the classification results back into the image domain, interpreting shape differences as a deformation required to bring a shape from one class to the other. An example of analyzing corpus callosum shape in schizophrenia is reported, as well as the results of the study of the statistical properties of the classifier using cross validation techniques. 1 Introduction Our goal is to build a framework for statistical shape analysis using classification techniques applied to feature descriptors. We perform shape feature extraction using skeletons. To make the process of ...
Deformable shape detection and description via modelbased region grouping
 IEEE Transactions on Pattern Analysis and Machine Intelligence
, 2001
"... AbstractÐA method for deformable shape detection and recognition is described. Deformable shape templates are used to partition the image into a globally consistent interpretation, determined in part by the minimum description length principle. Statistical shape models enforce the prior probabilitie ..."
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Cited by 47 (2 self)
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AbstractÐA method for deformable shape detection and recognition is described. Deformable shape templates are used to partition the image into a globally consistent interpretation, determined in part by the minimum description length principle. Statistical shape models enforce the prior probabilities on global, parametric deformations for each object class. Once trained, the system autonomously segments deformed shapes from the background, while not merging them with adjacent objects or shadows. The formulation can be used to group image regions obtained via any region segmentation algorithm, e.g., texture, color, or motion. The recovered shape models can be used directly in object recognition. Experiments with color imagery are reported. Index TermsÐImage segmentation, region merging, object detection and recognition, deformable templates, nonrigid shape models, statistical shape models. 1
Generalized Image Matching: Statistical Learning of PhysicallyBased Deformations
, 1996
"... We describe a novel approach for image matching based on deformable intensity surfaces. In this approach, the intensity surface of the image is modeled as a deformable 3D mesh in the (x; y; I(x;y)) space. Each surface point has 3 degrees of freedom, thus capturing fine surface changes. A set of repr ..."
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Cited by 46 (5 self)
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We describe a novel approach for image matching based on deformable intensity surfaces. In this approach, the intensity surface of the image is modeled as a deformable 3D mesh in the (x; y; I(x;y)) space. Each surface point has 3 degrees of freedom, thus capturing fine surface changes. A set of representative deformations within a class of objects (e.g. faces) are statistically learned through a Principal Components Analysis, thus providing a priori knowledge about objectspecific deformations. We demonstrate the power of the approach by examples such as image matching and interpolation of missing data. Moreover this approach dramatically reduces the computational cost of solving the governing equation for the physically based system by approximately three orders of magnitude.
Automatic landmark generation for point distribution models
 In Proc. British Machine Vision Conference
, 1994
"... Point Distribution Models (PDMs) are statistically derived flexible templates which are trained on sets of examples of the object(s) to be modelled. They require that each example is represented by a set of points (landmaiks) and that each landmark represents the same location on each of the example ..."
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Cited by 42 (6 self)
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Point Distribution Models (PDMs) are statistically derived flexible templates which are trained on sets of examples of the object(s) to be modelled. They require that each example is represented by a set of points (landmaiks) and that each landmark represents the same location on each of the examples. Generating the landmarks from 2D boundaries or 3D surfaces has previously been a manual process. Here, we describe a method for automatically generating PDMs from a training set of pixellated boundaries in 2D. The algorithm is a twostage process in which a pairwise corresponder is first used to establish an approximate set of landmarks on each of the example boundaries; in the second phase the landmarks are refined using an iterative nonlinear optimisation scheme to generate a more compact PDM. We present results for two objects the right hand and a chamber of the heart. The models generated using the automatically placed landmarks are shown to be better than those derived from landmarks located manually. 1
A Virtual Environment Testbed for Training Laparoscopic Surgical Skills
 Presence
, 2000
"... With the introduction of minimally invasive techniques, surgeons must learn skills and procedures that are radically di#erent from traditional open surgery. Traditional methods of surgical training that were adequate when techniques and instrumentation changed relatively slowly may not be as e#cient ..."
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Cited by 38 (7 self)
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With the introduction of minimally invasive techniques, surgeons must learn skills and procedures that are radically di#erent from traditional open surgery. Traditional methods of surgical training that were adequate when techniques and instrumentation changed relatively slowly may not be as e#cient or e#ective in training substantially new procedures. Virtual environments are a promising new medium for training. This paper describes a testbed developed at the San Francisco, Berkeley, and Santa Barbara campuses of the University of California for research in understanding, assessing, and training surgical skills. The testbed includes virtual environments for training perceptual motor skills, spatial skills, and critical steps of surgical procedures. Novel technical elements of the testbed include a four degreeoffreedom haptic interface, a fast collision detection algorithm for detecting contact between rigid and deformable objects, and parallel processing of physical modeling and rendering. The major technical challenge in surgical simulation to be investigated using the testbed is the development of accurate real time methods for modeling deformable tissue behavior. Several simulations have been implemented in the testbed, including environments for assessing performance of basic perceptual motor skills, training the use of an angled laparoscope, and teaching critical steps of a common laparoscopic procedure, the cholecystectomy. The major challenges of extending and integrating these tools for training are discussed. A Virtual Environment Testbed for Training Laparoscopic Surgical Skills 1 1
A Hierarchical Markov Modeling Approach for the Segmentation and Tracking of Deformable Shapes
, 1998
"... this paper, we develop a hierarchical statistical modeling framework for the representation, segmentation, and tracking of 2D deformable structures in image sequences. The model relies on the specification of a template, on which global as well as local deformations are defined. Global deformations ..."
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Cited by 38 (6 self)
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this paper, we develop a hierarchical statistical modeling framework for the representation, segmentation, and tracking of 2D deformable structures in image sequences. The model relies on the specification of a template, on which global as well as local deformations are defined. Global deformations are modeled using a statistical modal analysis of the deformations observed on a representative population. Local deformations are represented by a (firstorder) Markov random process. A modelbased segmentation of the scene is obtained by a joint bayesian estimation of global deformation parameters and local deformation variables. Spatial or spatiotemporal observations are considered in this estimation procedure, yielding an edgebased or a motionbased segmentation of the scene. The segmentation procedure is combined with a temporal tracking of the deformable structure over long image sequences, using a Kalman filtering approach. This combined segmentationtracking procedure has produced reliable extraction of deformable parts from long image sequences in adverse situations such as low signaltonoise ratio, nongaussian noise, partial occlusions, or random initialization. The approach is demonstrated on a variety of synthetic as well as realworld image sequences featuring different classes of deformable objects