This paper presents a new method to correct overlapping textures of a single 3D model where each texture was obtained under possibly different lighting conditions and color response of the camera. This situation arise...
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This paper presents a new method to correct overlapping textures of a single 3D model where each texture was obtained under possibly different lighting conditions and color response of the camera. This situation arises frequently when a single object is digitized using multiple 3D scanners. Our goal is to remove any visible seam and improve color consistency between the textures in order to merge them afterward. To achieve this, we propose an efficient algorithm to compute the "ratio lighting" of two textures, derive a common lighting from it, and use it to "relight" each texture. We illustrate our method by correcting textures of human faces acquired with several structured-light 3D scanners. Experimental results are realistic and demonstrate how this method can reduce the need to calibrate colors or explicitly solve for the illumination.
This paper brings a new method for line reconstruction from many perspective images by factorization of a matrix containing line correspondences. No point correspondences are used. We formulate the reconstruction from...
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ISBN:
(纸本)0769519008
This paper brings a new method for line reconstruction from many perspective images by factorization of a matrix containing line correspondences. No point correspondences are used. We formulate the reconstruction from line correspondences in the language of Plucker line coordinates. The reconstruction is posed as the factorization of 3m x n matrix S into the product S = QL of 3m x 6 projection matrix Q and 6 x n line matrix L, both satisfying Klein identities. The matrix S contains coordinates oflines detected in perspective images. Similarly to reconstruction from point correspondences in perspective images, the matrix S has to be properly rescaled before it can be factorized. We propose a scaling of image line coordinates based on trifocal tensors that is analogical to the scaling proposed by Strum and Triggs for points. We propose an SVD based factorization enforcing Klein identities on Q and L in a noise-free situation. We show experiments on real data that suggest that a good reconstruction may be obtained even if data is noisy and the identities are not enforced exactly. We also discuss an extension of the method for images with occlusions.
In addition to its technical merits as a challenging non-rigid motion and structural integrity analysis problem, quantitative estimation of cardiac regional functions and material characteristics has significant physi...
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ISBN:
(纸本)0769519008
In addition to its technical merits as a challenging non-rigid motion and structural integrity analysis problem, quantitative estimation of cardiac regional functions and material characteristics has significant physiological and clinical values. We have earlier developed a stochastic finite element framework for the simultaneous estimation of myocardial motion and material parameters from medical image sequences with an extended Kalman filter approach. In this paper, we present a new computational strategy for the framework based upon the maximum a posteriori estimation principles, realized through the extended Kalman smoother, that produce a sequence of kinematics state and material parameter estimates from the entire sequence of observations. The system dynamics equations of the heart is constructed using a biomechanical model with stochastic parameters, and the tissue material and deformation parameters are jointly estimated from the periodic imaging data. Experiments with canine magnetic resonance images have been conducted with very promising results, as validated through comparison to the histological staining of post mortem myocardium.
Depth from triangulation has traditionally been treated in a number of separate threads in the computer vision literature, with methods like stereo, laser scanning, and coded structured light considered separately. In...
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Depth from triangulation has traditionally been treated in a number of separate threads in the computer vision literature, with methods like stereo, laser scanning, and coded structured light considered separately. In this paper, we propose a common framework, spacetime stereo, that unifies many of these previous methods. Viewing specific techniques as special cases of this general framework leads to insights regarding the solutions to many of the traditional problems of individual techniques. Specifically, we discuss a number of innovative possible applications such as improved recovery of static scenes under variable illumination, spacetime stereo for moving objects, structured light and laser scanning with multiple simultaneous stripes or patterns, and laser scanning of shiny objects. To suggest the practical utility of the framework, we use it to analyze one of these applications-recovery of static scenes under variable, but uncontrolled, illumination. Based on our analysis, we show that methods derived from the spacetime stereo framework can be used to recover depth in situations in which existing methods perform poorly.
We have recently shown that 1) the infomax principle for the organization of perceptual systems leads to visual recognition architectures that are nearly optimal in the minimum Bayes error sense, and 2) a quantity whi...
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ISBN:
(纸本)0769519008
We have recently shown that 1) the infomax principle for the organization of perceptual systems leads to visual recognition architectures that are nearly optimal in the minimum Bayes error sense, and 2) a quantity which plays an important role in infomax solutions is the marginal diversity(MD): the average distance between the class conditional density of each feature and their mean. Since MD is a discriminant quantity and can be computed with great efficiency, the principle of maximum marginal diversity (MMD) was suggested for discriminant feature selection. In this paper, we study the optimality (in the infomax sense) of the MMD principle and analyze its effectiveness for feature selection in the context of visual recognition. In particular, 1) we derive a close form relation between the optimal infomax and MMD solutions, and 2) show that there is a family of classification problems for which the two are identical. Examination of this family in light of recent studies on the statistics of natural images suggests that the equivalence conditions are likely to hold for the problem of visual recognition. We present experimental evidence supporting the conclusions that 1) MD is a good predictor for the recognition ability of a given set of features, 2) MMD produces features that are more discriminant than those obtained with currently predominant criteria such as energy compaction, and 3) the extracted features are detectors of visual attributes that are perceptually relevant for low-level image classification.
Traditional approaches for surface reconstruction from range data require that the input data be either range images or unorganized sets of points. Since a large number of range sensors provide data along curvilinear ...
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ISBN:
(纸本)0769519008
Traditional approaches for surface reconstruction from range data require that the input data be either range images or unorganized sets of points. Since a large number of range sensors provide data along curvilinear patterns such as profiles, this paper presents an approach for reconstructing a surface from a set of unorganized curves. A strategy for updating the reconstructed surface during data acquisition is described as well. Curves are accumulated in a volumetric structure in which a vector field is built and updated. The information that is needed for efficient curve registration is also directly available in this vector field. This leads to a unified modeling approach combining surface reconstruction and curve registration. The algorithm implementing the approach is of linear complexity with respect to the number of input curves and makes it suitable for interactive modeling. Simulated data based on a set of six curvilinear patterns as well as data acquired with a range sensor are used to illustrate the various steps of the algorithm.
Design of experiments has already been used for several years in different domains. It is often ignored in imageprocessing. In this article, we would Re to show that it has it place in this area where it is common to...
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ISBN:
(纸本)0819449989
Design of experiments has already been used for several years in different domains. It is often ignored in imageprocessing. In this article, we would Re to show that it has it place in this area where it is common to have parameters to be adjusted according to the images to be processed and which should remain valid for a family of images of the same type. These parameters are often numerous and they frequently interfere with each others. The use of an active contour requires several parameters rather delicate to be adjusted. The experimental research methodology allows, the factors to be considered to be listed and then, from these, the identification of those which are the most influential, in order to optimize them.
A hand shape recognition is proposed as Graphical User Interface (GUI) which is very useful for a handicapped person to use a computer and many hand shape recognition algorithms were proposed until now. This paper com...
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ISBN:
(纸本)0780379063
A hand shape recognition is proposed as Graphical User Interface (GUI) which is very useful for a handicapped person to use a computer and many hand shape recognition algorithms were proposed until now. This paper compared five hand shape recognition algorithms, evaluate the hand shape recognition ratio, the processing.speed, and the extraction ratio on different colored background. From the results, the Algorithm2 (named in this paper) has the maximum recognition ratio in all hand shape recognition algorithms and it is 93.3[%]. The Algorithm1 and the Algorithm2 are faster processing.speed than other three algorithms. The extraction ratio have about 70[%] at least in each algorithm.
One of the main problems of optical data processing.is the problem of imagerecognition. There were given much attention to optoelectronic methods of recognition of distorted images nowadays. There are a number of dif...
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ISBN:
(纸本)0819449660
One of the main problems of optical data processing.is the problem of imagerecognition. There were given much attention to optoelectronic methods of recognition of distorted images nowadays. There are a number of different approaches for the solution of such problem. One of the most popular approaches is using of optical correlators for this field. The main problem of this approach is to select an object to provide a correlation of input image with it. One of the widespread methods is to use an effective object-an invariant correlation filter. The paper presents the results of investigations on imagerecognition with the help of Wavelet Basis Kernel Filters (WBKF). Both results of the theory and computer simulations are presented. Also computer simulations hold a comparison of imagerecognition results with the help of other different approaches (GMACE, SDF and so on). The obtained results seem to be better for WBKF recognition in some cases. There are presented authors suggestions about using of WBKF filters for different distortion invariant imagerecognition problems and results of imagerecognition in presence of white noise.
The performance of image retrieval with SVM active learning is known to be poor when started with few labelled images only. In this paper, the problem is solved by incorporating the unlabelled images into the bootstra...
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The performance of image retrieval with SVM active learning is known to be poor when started with few labelled images only. In this paper, the problem is solved by incorporating the unlabelled images into the bootstrapping of the learning process. In this work, the initial SVM classifier is trained with the few labelled images and the unlabelled images randomly selected from the image database. Both theoretical analysis and experimental results show that by incorporating unlabelled images in the bootstrapping, the efficiency of SVM active learning can be improved, and thus improves the overall retrieval performance.
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