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image-based modeling and elastic analysis of porous ceramics by the homogenization method

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 2002年第6期110卷 567-575页

作者： Kimura, K Takano, N Kubo, F Ogawa, S Kawamoto, H Zako, M Fine Ceram Res Assoc Synergy Ceram Lab Atsuta Ku Nagoya Aichi 4568587 Japan Osaka Univ Dept Mfg Sci Suita Osaka 5650871 Japan

A three-dimensional elastic analysis system for porous ceramics has been built. In this system, three-dimensional morphology of pores is modeled using voxel (volume pixel) elements from digital images. Elastic analysis with this image-based finite element model is performed by the homogenization method. In order to investigate this analysis system, the elastic properties and behavior of porous Al2O3 with spherical pores on the order of 1% by volume were computed. Young's moduli obtained by the homogenization method were consistent with both experimental and theoretical values. Using computed moduli of elasticity, the state of local stress concentration around the pores in a bending test was calculated together with the global stress in the sample. It was found that the dependence of the bending strength upon porosity can be described by taking into account local stresses around the pores. The combination of image-based modeling and homogenization method is a useful way to analyze the mechanical behavior of porous ceramics especially with inhomogeneous morphology.

关键词： computational mechanics porous ceramics image-based modeling three-dimensional modeling finite element method homogenization method voxel element

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image-based modeling by joint segmentation

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INTERNATIONAL JOURNAL OF COMPUTER VISION 2007年第1期75卷 135-150页

作者： Quan, Long Wang, Jingdong Tan, Ping Yuan, Lu Hong Kong Univ Sci & Technol Dept Comp Sci & Engn Hong Kong Hong Kong Peoples R China

The paper first traces the image-based modeling back to feature tracking and factorization that have been developed in the group led by Kanade since the eighties. Both feature tracking and factorization have inspired and motivated many important algorithms in structure from motion, 3D reconstruction and modeling. We then revisit the recent quasi-dense approach to structure from motion. The key advantage of the quasi-dense approach is that it not only delivers the structure from motion in a robust manner for practical modeling purposes, but also it provides a cloud of sufficiently dense 3D points that allows the objects to be explicitly modeled. To structure the available 3D points and registered 2D image information, we argue that a joint segmentation of both 3D and 2D is the fundamental stage for the subsequent modeling. We finally propose a probabilistic framework for the joint segmentation. The optimal solution to such a joint segmentation is still generally intractable, but approximate solutions are developed in this paper. These methods are implemented and validated on real data set.

关键词： structure from motion image-based modeling reconstruction segmentation

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image-based modeling of Blood Flow and Vessel Wall Dynamics: Applications, Methods and Future Directions

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ANNALS OF BIOMEDICAL ENGINEERING 2010年第3期38卷 1188-1203页

作者： Taylor, Charles A. Steinman, David A. Stanford Univ Dept Bioengn Stanford CA 94305 USA Stanford Univ Dept Surg Stanford CA 94305 USA Univ Toronto Dept Mech & Ind Engn Toronto ON Canada

The objective of our session at the 2008 International Bio-Fluid Symposium and Workshop was to review the state-of-the-art in image-based modeling of blood flow, and identify future directions. Here we summarize progress in the field of image-based modeling of blood flow and vessel wall dynamics from mid-2005 to early 2009. We first describe the tremendous progress made in the application of image-based modeling techniques to elucidate the role of hemodynamics in vascular pathophysiology, plan treatments for congenital and acquired diseases in individual patients, and design and evaluate endovascular devices. We then review the advances that have been made in improving the methodology for modeling blood flow and vessel wall dynamics in image-based models, and consider issues related to extracting hemodynamic parameters and verification and validation. Finally, the strengths and weaknesses of current work in image-based modeling and the opportunities and threats to the field are described. We believe that with a doubling of our efforts toward the clinical application of image-based modeling tools, the next few years could surpass the tremendous gains made in the last few.

关键词： image-based modeling Patient-specific Hemodynamics Atherosclerosis Aneurysms Surgical planning

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image-based modeling of objects and human faces

Image-based modeling of objects and human faces

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Conference on Videometrics and Optical Methods for 3D Shape Measurement

作者： Zhang, ZY Microsoft Res Redmond WA 98052 USA

ISBN: (纸本)0819439878

In this paper, I will provide an overview of our project on 3D object and face modeling from images taken by a free-moving camera. We strive to advance the state of the art in 3D computer vision, and develop flexible and robust techniques for ordinary users to gain 3D experience from a set of casually collected 2D images. Applications include product advertisement on the Web, virtual conference, and interactive games. We briefly cover the following topics: Camera calibration: determine a camera's internal parameters by just observing a planar pattern under unknown orientations. Stereo rectification: transform a pair of stereo images based on a geometric meaningful criterion such that the epipolar lines of the rectified images are aligned. This will considerably simplify the stereo matching process. image matching: match points and curves across images within a probabilistic relaxation framework. We can obtain a much richer description of a scene using both points and curves. 3D photo editing: Virtual or real objects can be inserted in the real images, while preserving the correct 3D information of the scene structure. Object modeling: A complete 3D model of an object is built by taking a number of snapshots around the object. Face modeling: With five mouse clicks, a 3D face model is built in a few minutes, and the model can be animated immediately. We have successfully built 3D face models for about one hundred people. Demos on the last three topics will be shown during the conference. Most of the above-described topics are joint work with Zicheng Liu, Charles Loop, and Ying Shan among other colleagues.

关键词： image-based modeling image-based rendering computer vision 3D vision face modeling face animation

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image-based modeling using a two-step camera calibration method

Image-based modeling using a two-step camera calibration met...

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International Symposium on Computer Graphics, image Processing, and Vision (SIBGRAPI 98)

作者： Carvalho, PCP Szenberg, F Gattass, M Inst Matemat Pura & Aplicada BR-22460320 Rio De Janeiro Brazil

ISBN: (纸本)0818692162

We present a two-step camera calibration process based on linear least squares formulations. We show how to apply this process to build an integrated modeling environment, in which a scene is modeled by having the user specify, on a given image? a set of reference points (used for camera calibration) and object points (used for positioning the objects in the scene). Once this has been done, synthetic information can be superimposed onto the image and arbitrary views can be produced. Using this methodology, we developed Virtual Referee, an application to analyze soccer plays from still images, generating an OpenGL camera over a 3D field model.

关键词： image-based modeling camera calibration computer vision

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Multiview Visibility Estimation for image-based modeling

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Journal of Computer Science & Technology 2011年第6期26卷 1000-1010页

作者：张柳新裴明涛贾云得 CCF Beijing Laboratory of Intelligent Information Technology School of Computer ScienceBeijing Institute of Technology

In this paper, we investigate the problem of determining regions in 3D scene visible to some given viewpoints when obstacles are present in the scene. We assume that the obstacles are composed of some opaque objects with closed surfaces. The problem is formulated in an implicit framework where the obstacles are represented by a level set function. The visible and invisible regions of the given viewpoints are determined through an efficient implicit ray tracing technique. As an extension of our approach, we apply the multiview visibility estimation to an image-based modeling technique. The unknown scene geometry and multiview visibility information are incorporated into a variational energy functional. By minimizing the energy functional, the true scene geometry as well as the accurate visibility information of the multiple views can be recovered from a number of scene images. This makes it feasible to handle the visibility problem of multiple views by our approach when the true scene geometry is unknown.

关键词： visibility estimation image-based modeling multiple views level set implicit surface

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image-based modeling of Blood Flow and Vessel Wall Dynamics: Applications, Methods and Future Directions

Image-Based Modeling of Blood Flow and Vessel Wall Dynamics:...

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5th International Biofluid Mechanics Symposium

作者： Taylor, Charles A. Steinman, David A. Stanford Univ Dept Bioengn Stanford CA 94305 USA Stanford Univ Dept Surg Stanford CA 94305 USA Univ Toronto Dept Mech & Ind Engn Toronto ON Canada

关键词： image-based modeling Patient-specific Hemodynamics Atherosclerosis Aneurysms Surgical planning

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image-based modeling TECHNIQUES FOR ARCHITECTURAL HERITAGE 3D DIGITALIZATION: LIMITS AND POTENTIALITIES 24

IMAGE-BASED MODELING TECHNIQUES FOR ARCHITECTURAL HERITAGE 3...

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24th International CIPA Symposium

作者： Santagati, C. Inzerillo, L. Di Paola, F. IEMEST Dept Commun Interact Graph & Augmented Real Ist Euro Mediterraneo Sci & Tecnol I-90139 Palermo Italy Univ Catania Dept Architecture I-95125 Catania Italy Univ Palermo Dept Architecture I-90139 Palermo Italy

ISBN: (纸本)9781629935201

3D reconstruction from images has undergone a revolution in the last few years. Computer vision techniques use photographs from data set collection to rapidly build detailed 3D models. The simultaneous applications of different algorithms (MVS), the different techniques of image matching, feature extracting and mesh optimization are inside an active field of research in computer vision. The results are promising: the obtained models are beginning to challenge the precision of laser-based reconstructions. Among all the possibilities we can mainly distinguish desktop and web-based packages. Those last ones offer the opportunity to exploit the power of cloud computing in order to carry out a semi-automatic data processing, thus allowing the user to fulfill other tasks on its computer;whereas desktop systems employ too much processing time and hard heavy approaches. Computer vision researchers have explored many applications to verify the visual accuracy of 3D model but the approaches to verify metric accuracy are few and no one is on Autodesk 123D Catch applied on Architectural Heritage Documentation. Our approach to this challenging problem is to compare the 3Dmodels by Autodesk 123D Catch and 3D models by terrestrial LIDAR considering different object size, from the detail (capitals, moldings, bases) to large scale buildings for practitioner purpose.

关键词： image-based modeling 3D reconstruction Computer Vision Architectural Heritage Laser scanning

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Changes in articular cartilage mechanics with meniscectomy: A novel image-based modeling approach and comparison to patterns of OA

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JOURNAL OF BIOMECHANICS 2011年第12期44卷 2307-2312页

作者： Haemer, Joseph M. Song, Yongnam Carter, Dennis R. Giori, Nicholas J. Stanford Univ Dept Mech Engn San Jose CA 95172 USA VA Palo Alto Hlth Care Syst Ctr Bone & Joint Palo Alto CA USA Korea Univ Dept Mech Engn Seoul South Korea Stanford Univ Dept Orthoped Surg San Jose CA 95172 USA

Meniscectomy is a significant risk factor for osteoarthritis, involving altered cell synthesis, central fibrillation, and peripheral osteophyte formation. Though changes in articular cartilage contact pressure are known, changes in tissue-level mechanical parameters within articular cartilage are not well understood. Recent imaging research has revealed the effects of meniscectomy on the time-dependent deformation of physiologically loaded articular cartilage. To determine tissue-level cartilage mechanics that underlie observed deformation, a novel finite element modeling approach using imaging data and a contacting indenter boundary condition was developed. The indenter method reproduces observed articular surface deformation and avoids assumptions about tangential stretching. Comparison of results from an indenter model with a traditional femur-tibia model verified the method, giving errors in displacement, solid and fluid stress, and strain below 1% (RMS) and 7% (max.) of the absolute maximum of the parameters of interest. Indenter finite element models using real joint image data showed increased fluid pressure, fluid exudation, loss of fluid load support, and increased tensile strains centrally on the tibial condyle after meniscectomy patterns corresponding to clinical observations of cartilage matrix damage and fibrillation. Peripherally there was decreased consolidation, which corresponds to reduced contact and fluid pressure in this analysis. Clinically, these areas have exhibited advance of the subchondral growth front, biological destruction of the cartilage matrix, cartilage thinning, and eventual replacement of the cartilage via endochondral ossification. Characterizing the changes in cartilage mechanics with meniscectomy and correspondence with observed tissue-level effects may help elucidate the etiology of joint-level degradation seen in osteoarthritis. (C) 2011 Elsevier Ltd. All rights reserved.

关键词： Osteoarthritis Meniscectomy Articular cartilage Finite element analysis Magnetic resonance imaging image-based modeling

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Evaluation of image-based modeling and laser scanning accuracy for emerging automated performance monitoring techniques

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AUTOMATION IN CONSTRUCTION 2011年第8期20卷 1143-1155页

作者： Golparvar-Fard, Mani Bohn, Jeffrey Teizer, Jochen Savarese, Silvio Pena-Mora, Feniosky Virginia Tech Charles E Via Dept Civil & Environm Engn Blacksburg VA 24061 USA Virginia Tech Myers Lawson Sch Construct Blacksburg VA 24061 USA Georgia Inst Technol Sch Civil & Environm Engn Atlanta GA 30332 USA Univ Michigan Ann Arbor MI 48109 USA Columbia Univ Fu Fdn Sch Engn & Appl Sci New York NY 10027 USA

Accurate and rapid assessment of the as-built status on any construction site provides the opportunity to understand the current performance of a project easily and quickly. Rapid project assessment further identifies discrepancies between the as-built and as-planned progress, and facilitates decision making on the necessary remedial actions. Currently, manual visual observations and surveying are the most dominant data capturing techniques but they are time-consuming, error-prone, and infrequent, making quick and reliable decision-making difficult. Therefore, research on new approaches that allow automatic recognition of as-built performance and visualization of construction progress is essential. This paper presents and compares two methods for obtaining point cloud models for detection and visualization of as-built status for construction projects: (1) A new method of automated image-based reconstruction and modeling of the as-built project status using unordered daily construction photo collections through analysis of Structure from Motion (SfM);(2) 3D laser scanning and analysis of the as-built dense point cloud models. These approaches provide robust means for recognition of progress, productivity, and quality on a construction site. In this paper, an overview of the newly developed automated image-based reconstruction approach and exclusive features which distinct it from other image-based or conventional photogrammetric techniques is presented. Subsequently the terrestrial laser scanning approach carried out for reconstruction and comparison of as-built scenes is presented. Finally the accuracy and usability of both of these techniques for metric reconstruction, automated production of point cloud models, 3D CAD shape modeling, and as-built visualizations is evaluated and compared on eight different case studies. It is shown that for precise defect detection or alignment tasks, image-based point cloud models may not be as accurate and dense as laser scanners

关键词： Progress monitoring image-based modeling Structure from motion Laser scanning Computer aided design Construction field imagery Range point clouds As-built modeling

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