While several image-based rendering techniques have been proposed to successfully render scenes/objects from a large collection (e.g., thousands) of images without explicitly recovering 3D structures, the minimum numb...
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While several image-based rendering techniques have been proposed to successfully render scenes/objects from a large collection (e.g., thousands) of images without explicitly recovering 3D structures, the minimum number of images needed to achieve a satisfactory rendering result remains an open problem. This paper is the first attempt to investigate the lower bound for the number of samples needed in the Lumigraph/light field rendering. To simplify the analysis, we consider an ideal scene with only a point that is between a minimum and a maximum range. Furthermore, constant-depth assumption and bilinear interpolation are used for rendering. The constant-depth assumption serves to choose 'nearby' rays for interpolation. Our criterion to determine the lower bound is to avoid horizontal and vertical double images, which are caused by interpolation using multiple nearby rays. This criterion is based on the causality requirement is scale-space theory, i.e., no 'spurious details' should be generated while smoothing. Using this criterion, closed-form solutions of lower bounds are obtained for both 3D plenoptic function (Concentric Mosaics) and 4D plenoptic function (light field). The bounds are derived completely from the aspect of geometry and are closely related to the resolution of the camera and the depth range of the scene. These lower bounds are further verified by our experimental results.
This paper introduces a method to calibrate a wide area system of unsynchronized cameras with respect to a single global coordinate system. The method is simple and does not require the physical construction of a larg...
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This paper introduces a method to calibrate a wide area system of unsynchronized cameras with respect to a single global coordinate system. The method is simple and does not require the physical construction of a large calibration object. The user need only wave an identifiable point in front of all cameras. The method generates a rough estimate of camera pose by first performing pair-wise structure-from-motion on observed points, and then combining the pair-wise registrations into a single coordinate frame. Using the initial camera pose, the moving point can be tracked in world space. The path of the point defines a 'virtual calibration object' which can be used to improve the initial estimates of camera pose. Iterating the above process yields a more precise estimate of both camera pose and the point path. Experimental results show that it performs as well as calibration from a physical target, in cases where all cameras share some common working volume. We then demonstrate its effectiveness in wide area settings by calibration a system of cameras in a configuration where traditional methods cannot be applied directly.
Motion estimation in image sequences is an important step in many computer vision and imageprocessing.applications. Several methods for solving this problem have been proposed, but very few manage to achieve a high l...
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This paper proposes a new expert system IMPRESS-Pro that automatically constructs an imageprocessing.procedure to decide whether there exists a specific figure in an image or not based on the requirement of misclassi...
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In this information-oriented society, the man-machine interface is a necessary technology, and comfortable operation for the user is desired. In this study, we are developing a new man-machine interface employing the ...
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In this information-oriented society, the man-machine interface is a necessary technology, and comfortable operation for the user is desired. In this study, we are developing a new man-machine interface employing the user's line of sight (LOS). With this new interface, the user can control the aspect of the multifunction monitoring camera using only his LOS. The LOS is calculated using imageprocessing. The image from the monitoring camera is projected on the monitor, and the user's LOS is shown as the cursor on the same monitor. We defined three LOS parameters for use in the interface: fixed gaze, shifting LOS, and disinterest. This study demonstrates the feasibility of one function of a man-machine interface using LOS. This interface can be used for monitoring shops and warehouses, or in remote conferencing systems.
In this paper, we address a few important image analysis problems, which are fundamental to the design of Perceptual User Interface (PUI). We use an inexpensive stationary desktop camera to collect the video streams a...
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ISBN:
(纸本)0819437034
In this paper, we address a few important image analysis problems, which are fundamental to the design of Perceptual User Interface (PUI). We use an inexpensive stationary desktop camera to collect the video streams and use them as input to the system. We present an algorithm for segmenting moving: foreground object of interest from a complex, but stationary background. This algorithm can cope with illumination changes due to shadows, Automatic Exposure Correction (AEC) and long term illumination changes in the environment. The segmentation is done real time and works well for both indoor and outdoor scenes. The detected foreground is recognized as human being based on head shoulder profile. The head shoulder profile is extracted as a pattern using an unique physics based approach, which is robust to noise and eliminates the need of median filtering to remove noise. We obtain Ring Data Vectors as features from the pattern, which is used to classify them into different clusters. The patterns which are similar form a cluster in the N dimensional vector space formed by the orthogonal basis of Ring Data Vectors. a data set for each possible cluster is formed by initial training and manual classification of different sets of patterns belonging to different human pose. Unknown new pattern extracted from the segmented foreground is synthetically recognized and classified into one of the existing template pattern. The system has been used in design of Visual computer games and can be used in the design of PUI's for pervasive computing applications, surveillance etc.
This paper explores the utilization of adaptive triangular meshes representing gray-level images to accelerate basic imageprocessing.operations. In particular, two algorithms for thresholding and labeling gray-level ...
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Content based image retrieval is the task of searching images from a database, which are visually similar to a given example image. We present methods for content based image retrieval based on texture similarity usin...
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We present a multiview method for the computation of object shape and reflectance characteristics based on the integration of shape from shading (SFS) and stereo, for non-constant albedo and non-uniformly Lambertian s...
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We present a multiview method for the computation of object shape and reflectance characteristics based on the integration of shape from shading (SFS) and stereo, for non-constant albedo and non-uniformly Lambertian surfaces. First we perform stereo fitting on the input stereo pairs or image sequences. When the images are uncalibrated, we recover the camera parameters using bundle adjustment. Based on the stereo result, we can automatically segment the albedo map (which is taken to be piece-wise constant) using a Minimum Description Length (MDL) based metric, to identify areas suitable for SFS (typically smooth textureless areas) and to derive illumination information. The shape and the illumination parameter estimates are refined using a deformable model SFS algorithm, which iterates between computing shape and illumination parameters. Our method takes into account the viewing angle dependent foreshortening and specularity effects, and compensates as much as possible by utilizing information from more than one images. We demonstrate that we can extend the applicability of SFS algorithms to real world situations when some of its traditional assumptions are violated. We demonstrate our method by applying it to face shape reconstruction. Experimental results indicate a significant improvement over SFS-only or stereo-only based reconstruction. Model accuracy and detail are improved, especially in areas of low texture detail. Albedo information is retrieved and can be used to accurately re-render the model under different illumination conditions.
Agent-based approaches have not yet been widely applied to highly complex, data intensive, large-scale information processing.systems such as are found in the domain of imagery & geospatial computing. Such systems...
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