A novel depth-from-focus technique is introduced that needs only a single image. It is based on a precise knowledge of the 3-D point spread function and requires objects of uniform brightness and simple shapes. Using ...
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ISBN:
(纸本)0818658258
A novel depth-from-focus technique is introduced that needs only a single image. It is based on a precise knowledge of the 3-D point spread function and requires objects of uniform brightness and simple shapes. Using adequate low-level imageprocessing.techniques, the true area of the object and the distance from the focal plane is obtained from parameters such as the apparent (blurred) area of the object and the mean brightness in this area. The technique has been applied to measure the size distribution of bubbles submerged by breaking waves. A depth criterion is used to define a virtual measuring volume that is roughly proportional to the size of the bubbles.
A transitory image sequence is one in which no scene element is visible through the entire sequence. This article deals with some major theoretical and algorithmic issues associated with the task of estimating structu...
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ISBN:
(纸本)0818658258
A transitory image sequence is one in which no scene element is visible through the entire sequence. This article deals with some major theoretical and algorithmic issues associated with the task of estimating structure and motion from transitory image sequences. Two representations, world-centered (WC) and camera-centered (CC), behave very differently with a transitory sequence. The asymptotical error properties derived in this article indicate that one representation is significantly superior to the other, depending on whether one uses camera-centered or world-centered estimates. Rigorous experiments were conducted with real-image sequences taken by a fully calibrated camera system. The comparison of the experimental results with the ground truth has demonstrated that a good accuracy can be obtained from transitory image sequences.
image monitoring, the process of locating and identifying significant changes or new activities, is one of the most important imagery exploitation tasks. A site model supported image monitoring system which utilizes i...
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ISBN:
(纸本)0818658258
image monitoring, the process of locating and identifying significant changes or new activities, is one of the most important imagery exploitation tasks. A site model supported image monitoring system which utilizes image understanding techniques driven by an underlying site model is presented. In our approach, we first register the image to be monitored to an existing site model, which is constructed using the RADIUS Common Development Environment;the regions of interest are then delineated based on site information, camera acquisition parameters, and goals of the image analyst;object extraction is then done using constraints on size, shape, orientation, and shadow of the target object derived from known information about image resolution, 3-D shape of the object, camera viewing and illuminant directions. The results of object detection are used for monitoring changes.
A new method for generating x-y separable steerable scalable approximations of filter kernels is proposed which is based on a generalization of the Singular Value Decomposition (SVD) to 3 dimensions. This 'pseudo-...
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ISBN:
(纸本)0818658258
A new method for generating x-y separable steerable scalable approximations of filter kernels is proposed which is based on a generalization of the Singular Value Decomposition (SVD) to 3 dimensions. This 'pseudo-SVD' improves upon a previous scheme due to Perona in that it reduces convolution time and storage requirements. An adaptation of the pseudo-SVD is proposed to generate steerable and scalable kernels which are suitable for use with a Laplacian pyramid. The properties of this method are illustrated experimentally in generating steerable and scalable approximations to an early vision edge-detection kernel.
A method for computing the 3D camera motion (the ego-motion) in a static scene is introduced, which is based on computing the 2D image motion of a single image region directly from image intensities. The computed imag...
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ISBN:
(纸本)0818658258
A method for computing the 3D camera motion (the ego-motion) in a static scene is introduced, which is based on computing the 2D image motion of a single image region directly from image intensities. The computed image motion of this image region is used to register the images so that the detected image region appears stationary. The resulting displacement field for the entire scene between the registered frames is affected only by the 3D translation of the camera. After canceling the effects of the camera rotation by using such 2D image registration, the 3D camera translation is computed by finding the focus-of-expansion in the translation-only set of registered frames. This step is followed by computing the camera rotation to complete the computation of the ego-motion. The presented method avoids the inherent problems in the computation of optical flow and of feature matching, and does not assume any prior feature detection or feature correspondence.
Low-level motion estimators based on differential, tensor, and phase methods are reformulated in a unified way as filter methods in the continuous space-time domain. This approach allows inherent conceptual deficits t...
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ISBN:
(纸本)0818658258
Low-level motion estimators based on differential, tensor, and phase methods are reformulated in a unified way as filter methods in the continuous space-time domain. This approach allows inherent conceptual deficits to be distinguished from those related to the implementation in discrete space. A detailed analytical error analysis is performed. All techniques yield unbiased motion estimates for areas of constant velocity with any type of gray value structure in continuous space. Errors are only introduced by an inadequate discrete implementation. Further investigated are the influence of zero-mean normal distributed noise, spatially and temporally (accelerated) varying motion, motion discontinuities, and illumination changes. The main results of the paper are also illustrated with real-world image sequences.
This paper presents a new method for extracting the 3-D shape and texture of an object undergoing translational motion from image sequences captured through a monocular extra-wide picture viewing angle. The feature of...
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ISBN:
(纸本)0818658258
This paper presents a new method for extracting the 3-D shape and texture of an object undergoing translational motion from image sequences captured through a monocular extra-wide picture viewing angle. The feature of this work is extracting this information from image sequences without requiring rigid environmental conditions. In this method, the relative positions between target and view position are estimated based on spatio-temporal image analysis, and shape is reconstructed from the multiple silhouette information. After reconstructing the 3-D shape, the voxel value of a surface point is determined by statistically analyzing those images that contain the surface point. The proposed method can extract 3-D shape and surface texture at a stroke from outdoor scenes. An experiment using real outdoor scenes confirms the effectiveness of the method.
The proceedings contains 165 papers on computer vision and patternrecognition. Topics discussed include recognition systems, imageprocessing. computational methods, algorithms and information use.
ISBN:
(纸本)0818658274
The proceedings contains 165 papers on computer vision and patternrecognition. Topics discussed include recognition systems, imageprocessing. computational methods, algorithms and information use.
In this paper, we present a system for detection, tracking and representation of tubular objects in images. The uniqueness of the proposed system is twofold: at the macro level, the novelty of the system lies in the i...
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ISBN:
(纸本)0818658258
In this paper, we present a system for detection, tracking and representation of tubular objects in images. The uniqueness of the proposed system is twofold: at the macro level, the novelty of the system lies in the integration of object localization and tracking using geometric properties;at the micro level, in the use of high and low level constraints to model the detection and tracking subsystem. The underlying philosophy for object detection is to extract perceptually significant features from the pixel level image, and then use these high level cues to refine the precise boundaries. In the case of tubular objects, the perceptually significant features are anti-parallel line segments or, equivalently, their axis of symmetries. The axis of symmetry infers a coarse description of the object in terms of a bounding polygon. The polygon then provides the necessary boundary condition for the refinement process, which is based on dynamic programming. For tracking the object in a time sequence of images, the refined contour is then projected onto each consecutive frame. In addition, the system provides an axis of symmetry representation of object for subsequent scientific analysis.
In this paper, we present a method for registering images of complex 3-D surfaces that does not require explicit correspondences between features across the images. Our method relies on the use of a full 3-D model of ...
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ISBN:
(纸本)0818658258
In this paper, we present a method for registering images of complex 3-D surfaces that does not require explicit correspondences between features across the images. Our method relies on the use of a full 3-D model of the surface to adjust the position and orientation of the camera by minimizing an objective function based on the projections of the images onto the model. This approach constrains the camera parameters strongly enough so that the models do not need, initially, to be accurate to yield good results. When registration has been achieved, the models can be refined and the fine details recovered. Our method is applicable to the calibration of stereo imagery, the precise registration of new images of a scene and the tracking of deformable objects. It can therefore lead to important applications in fields such as augmented reality in a medical context or data compression for transmission purposes. We demonstrate its applicability by using images of faces and of terrain.
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