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Reconstruction of 3D object meshes from silhouette images

JOURNAL OF MAthEMATICAL IMAGING AND VISION 2007年第2-3期29卷 119-130页

作者： Montenegro, Anselmo Antunes Velho, Luiz Carvalho, Paulo C. P. Sossai, Jonas, Jr. Univ Fed Fluminense Dept Ciencia Comp BR-24210240 Niteroi RJ Brazil Inst Nacl Matemat Pura & Aplicada Rio De Janeiro Brazil

In this work we propose a method for computing mesh representations of 3D objects reconstructed from a set of silhouette images. Our method is based on the polygonization of volumetric reconstructions by using a modified version of the dual contouring method. In order to apply dual contouring on volumetric reconstruction from silhouettes we devised a method that is able to determine the discrete topology of the surface in relation to the octree cells. We also developed a new scheme for computing hermitian data representing the intersections of conic volumes with the octree cells and their corresponding normals with subpixel accuracy. Due to the discrete and extremely noisy nature of the data used in the reconstruction we had to devise a different criterion for mesh simplification that applies topological consistency tests only when the geometric error measure is beyond a given tolerance. We present results of the application of the proposed method in the extraction of a mesh corresponding to the surface of objects of a real scene.

关键词： polygonization of volumetric reconstructions mesh reconstruction from silhouettes dual contouring octree polygonization Visual hulls image-based modeling mesh simplification

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Generalized rigid and generalized affine image registration and interpolation by geometric multigrid

Generalized rigid and generalized affine image registration ...

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19th brazilian symposium on computer graphics and image processing (sibgrapi 2006)

作者： Keeling, Stephen L. Karl Franzens Univ Graz Inst Math & Wissenschaftliches Rechmen A-8010 Graz Austria

Generalized rigid and generalized affine registration and interpolation obtained by finite displacements and by optical flow are here developed variationally and numerically as well as with respect to a geometric multigrid solution process. For high order optimality systems under natural boundary conditions, it is shown that the convergence criteria of Hackbusch (Iterative Solution of Large Sparse Systems of Equations. Springer, Berlin, 1993) are met. Specifically, the Galerkin formalism is used together with a multi-colored ordering of unknowns to permit vectorization of a symmetric successive over-relaxation on image processing systems. the geometric multigrid procedure is situated as an inner iteration within an outer Newton or lagged diffusivity iteration, which in turn is embedded within a pyramidal scheme that initializes each outer iteration from predictions obtained on coarser levels. Differences between results obtainable by finite displacements and by optical flows are elucidated. Specifically, independence of image order can be shown for optical flow but in general not for finite displacements. Also, while autonomous optical flows are used in practice, it is shown explicitly that finite displacements generate a broader class of registrations. this work is motivated by applications in histological reconstruction and in dynamic medical imaging, and results are shown for such realistic examples.

关键词： generalized rigid generalized affine image registration image interpolation geometric multigrid

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Convergence of map seeking circuits

Convergence of map seeking circuits

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19th brazilian symposium on computer graphics and image processing (sibgrapi 2006)

作者： Gedeon, Tomas Arathorn, David Montana State Univ Dept Math Sci Bozeman MT 59715 USA Montana State Univ Gen Intelligence Corp Ctr Computat Biol Bozeman MT 59715 USA

the map-seeking circuit (MSC) is an explicit biologically-motivated computational mechanism which provides practical solution of problems in object recognition, image registration and stabilization, limb inverse-kinematics and other inverse problems which involve transformation discovery. We formulate this algorithm as discrete dynamical system on a set Delta = Pi(L)(l=1)Delta((l)), where each Delta((l)) is a compact subset of a nonnegative orthant of R-n, and show that for an open and dense set of initial conditions in Delta the corresponding solutions converge to either a vector with unique nonzero element in each Delta((l)) or to a zero vector. the first result implies that the circuit finds a unique best mapping which relates reference pattern to a target pattern;the second result is interpreted as "no match found". these results verify numerically observed behavior in numerous practical applications.

关键词： map seeking circuits computer vision dynamical systems Lyapunov function

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Mumford-Shah on the move: Region-based segmentation on deforming manifolds with application to 3-D reconstruction of shape and appearance from multi-view images

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JOURNAL OF MAthEMATICAL IMAGING AND VISION 2007年第2-3期29卷 219-234页

作者： Jin, Hailin Yezzi, Anthony J. Soatto, Stefano Adobe Syst Inc Off Tech San Jose CA 95110 USA Georgia Inst Technol Sch Elect & Comp Engn Atlanta GA 30332 USA Univ Calif Los Angeles Dept Comp Sci Los Angeles CA 90025 USA

We address the problem of estimating the shape and appearance of a scene made of smooth Lambertian surfaces with piecewise smooth albedo. We allow the scene to have self-occlusions and multiple connected components. this class of surfaces is often used as an approximation of scenes populated by man-made objects. We assume we are given a number of images taken from different vantage points. Mathematically this problem can be posed as an extension of Mumford and Shah's approach to static image segmentation to the segmentation of a function defined on a deforming surface. We propose an iterative procedure to minimize a global cost functional that combines geometric priors on both the shape of the scene and the boundary between smooth albedo regions. We carry out the numerical implementation in the level set framework.

关键词： variational methods Mumford-Shah functional image segmentation multi-view stereo level set methods curve evolution on surfaces dense shape reconstruction structure from motion visibility

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Directional analysis of images with gabor wavelets 13

Directional analysis of images with gabor wavelets

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13th brazilian symposium on computer graphics and image processing, sibgrapi 2000

作者： Rangayyan, R.M. Ferrari, R.J. Desautels, J.E.L. Frère, A.F. Department of Electrical and Computer Engineering University of Calgary CalgaryABT2N 1N4 Canada Department of Electrical Engineering University of São Paulo São Carlos SP13560-250 Brazil Alberta Cancer Board CalgaryABT2P 3G9 Canada Nucleus of Science and Technology University of Mogi das Cruzes Mogi das Cruzes SP Brazil

ISBN: (纸本)0769508782

this paper presents a new scheme for analysis of linear directional components in images by using a multiresolution representation based on Gabor wavelets. A dictionary of Gabor filters with varying tuning frequency and orientation, specifically designed in order to reduce the redundancy in the wavelet-based representation, is applied to the given image. the filter responses for different scales and orientation are analyzed by using the Karhunen-Loève (KL) transform and Otsu's method of thresholding. the KL transform is applied to select the principal components of the filter responses, preserving only the most relevant directional elements appearing at all scales. the first N principal components, thresholded by using Otsu's method, are used to reconstruct the magnitude and phase of the directional components of the image. In this work, Rose diagrams computed from the phase images are used for quantitative and qualitative analysis of the oriented patterns. the proposed scheme is applied to the analysis of asymmetry between left and right mammograms. For this purpose, a set of three features is extracted from the Rose diagrams and used in a parametric statistical classifier. A total of 80 images from 20 normal cases, 14 asymmetric cases, and 6 distortion cases from the Mini-MIAS database were used to evaluate the scheme using the leave-one-out methodology, resulting in an average diagnostic accuracy of 72.5%. © 2000 IEEE.

关键词： Gabor filters

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Time-critical rendering of irregular grids 13

Time-critical rendering of irregular grids

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13th brazilian symposium on computer graphics and image processing, sibgrapi 2000

作者： Farias, Ricardo Mitchell, Joseph S.B. Silva, Cláudio T. Wylie, Brian Department of Applied Mathematics and Statistics State University of New York at Stony Brook Stony BrookNY11794-3600 United States AT and T Labs-Research 180 Park Ave. PO Box 971 Florham ParkNJ07932 United States Sandia National Laboratories MS 0318 PO Box 5800 Org 9215 AlbuquerqueNM87185 United States

ISBN: (纸本)0769508782

Many papers have presented rendering techniques and simplification ideas with the objective of speeding up image generation for irregular grid data sets. For large data sets, however, even the current fastest algorithms are known to require seconds to generate each image, making real-time analysis of such data sets very difficult, or even impossible, unless one has access to powerful and expensive computer hardware. In order to synthesize a system for handling very large data sets analysis, we have assembled algorithms for rendering, simplification and triangulation, and added to them some optimizations. We have made some improvements on one of the best current algorithms for rendering irregular grids, and added to it some simple approximation methods in both image and object space, resulting in a system that achieves high frame rates, even on slow computers without any specific graphic hardware. the algorithm adapts itself to the time budget it has available for each image generation, using hierarchical representations of the mesh for faster delivery of images when transformations are imposed to the data. When given additional time, the algorithm generates finer images, obtaining the precise final image if given sufficient time. We were able to obtain frame rates of the order of 5Hz for medium-sized data sets, which is about 20 times faster than previous rendering algorithms. With a trade-off between image accuracy and speed, similar frame rates can be achieved on different computers. © 2000 IEEE.

关键词： computer hardware

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Reconstruction of 3D object meshes from silhouette images

Reconstruction of 3D object meshes from silhouette images

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19th brazilian symposium on computer graphics and image processing (sibgrapi 2006)

关键词： polygonization of volumetric reconstructions mesh reconstruction from silhouettes dual contouring octree polygonization Visual hulls image-based modeling mesh simplification

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Fast, precise flattening of cubic Bezier segment offset curves

Fast, precise flattening of cubic Bezier segment offset curv...

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brazilian symposium on computer graphics and image processing (sibgrapi)

作者： T.F. Hain S.V.R. Racherla D.D. Langan School of CIS University of South Alabama AL USA SL Technologies Biloxi MS USA

A fast algorithm for generating a polyline approximation (flattening) for the offset curves of a cubic Bezier curve segment is described. It is shown to be more efficient than the standard recursive subdivision method by generating only 70% as many segments, but, just as importantly, 94% of all segments fall within 20% of the flatness criterion. the code runs as fast as recursive subdivision.

关键词： Linear approximation Approximation methods computer graphics image processing

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Automatic image segmentation by tree pruning

Automatic image segmentation by tree pruning

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19th brazilian symposium on computer graphics and image processing (sibgrapi 2006)

作者： Bergo, Felipe P. G. Falcao, Alexandre X. Miranda, Paulo A. V. Rocha, Leonardo M. Univ Estadual Campinas LIV Inst Comp BR-13083970 Campinas SP Brazil Univ Estadual Campinas DECOM FEEC BR-13083970 Campinas SP Brazil

the image Foresting Transform (IFT) is a tool for the design of image processing operators based on connectivity, which reduces image processing problems into an optimum-path forest problem in a graph derived from the image. A new image operator is presented, which solves segmentation by pruning trees of the forest. An IFT is applied to create an optimum-path forest whose roots are seed pixels, selected inside a desired object. In this forest, object and background are connected by optimum paths (leaking paths), which cross the object's boundary through its "most weakly connected" parts (leaking pixels). these leaking pixels are automatically identified and their subtrees are eliminated, such that the remaining forest defines the object. Tree pruning runs in linear time, is extensible to multidimensional images, is free of ad hoc parameters, and requires only internal seeds, with little interference from the heterogeneity of the background. these aspects favor solutions for automatic segmentation. We present a formal definition of the obtained objects, algorithms, sufficient conditions for tree pruning, and two applications involving automatic segmentation: 3D MR-image segmentation of the human brain and image segmentation of license plates. Given that its most competitive approach is the watershed transform by markers, we also include a comparative analysis between them.

关键词： image segmentation graph-search algorithms image foresting transform image processing watershed transform

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Mumford-Shah on the move: Region-based segmentation on deforming manifolds with application to 3-D reconstruction of shape and appearance from multi-view images

Mumford-Shah on the move: Region-based segmentation on defor...

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19th brazilian symposium on computer graphics and image processing (sibgrapi 2006)

关键词： variational methods Mumford-Shah functional image segmentation multi-view stereo level set methods curve evolution on surfaces dense shape reconstruction structure from motion visibility

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