We present a new method for the 3D model-based tracking of human body parts. To mitigate the difficulties arising due to occlusion among body parts, we employ multiple calibrated cameras in a mutually orthogonal confi...
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ISBN:
(纸本)0818672587
We present a new method for the 3D model-based tracking of human body parts. To mitigate the difficulties arising due to occlusion among body parts, we employ multiple calibrated cameras in a mutually orthogonal configuration. In addition, we develop criteria for a time varying active selection of a set of cameras to track the motion of a particular human part. In particular, at every frame, each camera tracks a number of parts depending on the visibility of these parts and the observability of their predicted motion from the specific camera. To relate points on the occluding contours of the parts to points on their models we apply concepts from projective geometry. Then, within the physics-based framework we compute the generalized forces applied from the parts' occluding contours to model points of the body parts. These forces update the translational and rotational degrees of freedom of the model, such as to minimize the discrepancy between the sensory data and the estimated model state. We present initial tracking results from a series of experiments involving the recovery of complex 3D motions in the presence of significant occlusion.
Variations in pose, expression, illumination, aging and disguise are considered as major challenges in face recognition and several techniques have been proposed to address these challenges. Plastic surgery, on the ot...
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ISBN:
(纸本)9781424439942
Variations in pose, expression, illumination, aging and disguise are considered as major challenges in face recognition and several techniques have been proposed to address these challenges. Plastic surgery, on the other hand, is considered as an arduous research issue;however, it has not yet been studied either theoretically, or experimentally This paper focuses on analyzing the effect of plastic surgery in face recognition algorithms. The preliminary study provides an experimental and analytical comparison of face recognition algorithms on a plastic surgery, database of 506 individuals. The experimental results indicate that existing face recognition algorithms perform poorly when matching pre and post surgery face images. The results also suggest that it is imperative for future face recognition systems to be able to address this important issue and hence there is a need for more research in this important area.
Faces represent complex, multidimensional, meaningful visual stimuli and developing a computational model for face recognition is difficult. We present a hybrid neural network solution which compares favorably with ot...
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ISBN:
(纸本)0818672587
Faces represent complex, multidimensional, meaningful visual stimuli and developing a computational model for face recognition is difficult. We present a hybrid neural network solution which compares favorably with other methods. The system combines local image sampling, a self-organizing map neural network, and a convolutional neural network. The self-organizing map provides a quantization of the image samples into a topological space where inputs that are nearby in the original space are also nearby in the output space, thereby providing dimensionality reduction and invariance to minor changes in the image sample, and the convolutional neural network provides for partial invariance to translation, rotation, scale, and deformation. The method is capable of rapid classification, requires only fast, approximate normalization and preprocessing, and consistently exhibits better classification performance than the eigenfaces approach on the database considered as the number of images per person in the training database is varied from 1 to 5. With 5 images per person the proposed method and eigenfaces result in 3.8% and 10.5% error respectively. The recognizer provides a measure of confidence in its output and classification error approaches zero when rejecting as few as 10% of the examples. We use a database of 400 images of 40 individuals which contains quite a high degree of variability in expression, pose, and facial details.
A demonstration of a software prototype, called VADIS, (Video Analysis, Display and Indexing System) is presented. The functionality of VADIS includes real-time indexing of incoming live video stream using color histo...
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ISBN:
(纸本)0818684976
A demonstration of a software prototype, called VADIS, (Video Analysis, Display and Indexing System) is presented. The functionality of VADIS includes real-time indexing of incoming live video stream using color histogram based frame differencing, non-real-time cut detection and indexing of Motion JPEG or MPEG-1 video files. It includes a feature to save the indices and the storyboard generated during the indexing process.
Reliable detection and tracking of eyes is an important requirement for attentive user interfaces. In this paper we present a methodology for detecting eyes robustly in indoor environments in real-time. We exploit the...
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ISBN:
(纸本)0769506623
Reliable detection and tracking of eyes is an important requirement for attentive user interfaces. In this paper we present a methodology for detecting eyes robustly in indoor environments in real-time. We exploit the physiological properties and appearance of eyes as well as head/eye motion dynamics. Infrared lighting is used to capture the physiological properties of eyes, Kalman trackers are used to model eye/head dynamics, and a probabilistic based appearance model is used to represent eye appearance. By combining three separate modalities, with specific enhancements within each modality, our approach allows eyes to be treated as robust features that can be used for other higher-level processing.
In this paper we undertake a systematic investigation of affine invariant object detection. Edge detection is first presented from the point of view of the affine invariant scale-space obtained by curvature based moti...
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ISBN:
(纸本)0818672587
In this paper we undertake a systematic investigation of affine invariant object detection. Edge detection is first presented from the point of view of the affine invariant scale-space obtained by curvature based motion of the image level-sets. In this case, affine invariant edges are obtained as a weighted difference of images at different scales. We then introduce the affine gradient as the simplest possible affine invariant differential function which has the same qualitative behavior as the Euclidean gradient magnitude. These edge detectors are the basis both to extend the affine invariant scale-space to a complete affine flow for image denoising and simplification, and to define affine invariant active contours for object detection and edge integration. The active contours are obtained as a gradient flow in a conformally Euclidean space defined by the image on which the object is to be detected. That is, we show that objects can be segmented in an affine invariant manner by computing a path of minimal weighted affine distance, the weight being given by functions of the affine edge detectors. The geodesic path is computed via an algorithm which allows to simultaneously detect any number of objects independently of the initial curve topology.
The demo presents a virtual min-or interface which reacts to the viewer using robust, real-time face tracking. The display directly combines a user's face with various graphical distortions, performed only on the ...
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ISBN:
(纸本)0818684976
The demo presents a virtual min-or interface which reacts to the viewer using robust, real-time face tracking. The display directly combines a user's face with various graphical distortions, performed only on the face region in the image. The face detection and tracking is done in real-time, so the graphical effect stays with the user and continues to adapt as they move within the viewing space, increasing in intensity as the user approaches the display.
The silhouette of a smooth 3D object observed by a moving camera changes over time. Past work has shown how surface geometry can be recovered using the deformation of the silhouette when the camera motion is known. Th...
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ISBN:
(纸本)0818672587
The silhouette of a smooth 3D object observed by a moving camera changes over time. Past work has shown how surface geometry can be recovered using the deformation of the silhouette when the camera motion is known. This paper addresses the problem of estimating both the full Euclidean surface structure and the camera motion from a dense set of silhouettes captured under orthographic or scaled orthographic projection. The approach relies on a viewpoint-invariant representation of curves swept by viewpoint-dependent features such as bitangents, inflections and contour points with parallel tangents. Feature points, which form stereo frontier points between non-consecutive images, are matched using this representation. The camera's angular velocity is computed from constraints derived from this correspondence along with the image velocity of these features. From the angular velocity, the epipolar geometry is ascertained, and infinitesimal motion frontier points can be detected. In turn, the motion of these frontier points constrains the translation component of camera motion. Finally, the surface is reconstructed using established techniques once the camera motion has been estimated.
Full-perspective mappings between 3-D objects and 2-D images are more complicated than weak-perspective mappings, which consider only rotation, translation, and scaling. Therefore, in 3-D model-based robot navigation,...
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A computational framework for an accurate, robust, and efficient stereo approach is developed. Most of the deficiencies prevailing in current computational models of stereo can be attributed to their use of a single, ...
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