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34th International Conference on Computer Graphics (CGI)

作者： Iwasaki, Kei Dobashi, Yoshinori Okabe, Makoto Wakayama Univ UEI Res Wakayama Japan Hokkaido Univ UEI Res Sapporo Hokkaido Japan Shizuoka Univ Shizuoka Japan

ISBN: (纸本)9781450352284

In this paper, we propose a modeling method of clouds from a single photograph. To synthesize realistic images of outdoor scenes, modeling of 3D clouds is necessary. However, synthesizing realistic clouds is still a difficult task. To address this problem, we propose an example-based volume texture synthesis to model non-homogeneous density volumes. Our method prepares an example cloud volume data using a physically-based fluid simulator. Then the output cloud volume is automatically synthesized from the example cloud volume data so that its rendered image becomes similar to the clouds in the input photograph. In contrast to the previous texture synthesis methods, our method synthesizes density volumes taking into account scattering and transmittance of light. We show several cloud volumes whose rendered images are similar to the input photograph.

关键词： image-based modeling natural phenomena texture synthesis

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Shape-from-Shifting: Uncalibrated Photometric Stereo with a Mobile Device 13

Shape-from-Shifting: Uncalibrated Photometric Stereo with a ...

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13th Annual IEEE International Conference on e-Science (e-Science)

作者： Yeh, Chia-Kai Li, Fengqiang Pastorelli, Gianluca Walton, Marc Katsaggelos, Aggelos K. Cossairt, Oliver Northwestern Univ Dept Elect Engn & Comp Sci Evanston IL 60208 USA Northwestern Univ Ctr Sci Studies Arts NU ACCESS Evanston IL USA

ISBN: (纸本)9781538626863

Surface shape scanning techniques, such as laser scanning and photometric stereo, are widespread analytical tools used in the field of cultural heritage. Compared to regular 2D RGB photos, 3D surface scans provide higher fidelity of an object's surface shape which assist conservators, art historians, and archaeologists in understanding how these artworks and artifacts are made and to digitally document them for purposes of conservation. However, current state-of-the-art 3D surface scanning tools used in art conservation are often expensive and bulky-such as light dome structures that are often over 1 m in diameter. In this paper, we introduce mobile shape-from-shifting (SfS): a simple, low-cost and streamlined photometric stereo framework for scanning planar surfaces with a consumer mobile device coupled to a low-cost add-on component. Our free-form mobile SfS framework relaxes the rigorous hardware and other complex requirements inherent to conventional 3D scanning tools. This is achieved by taking a sequence of photos with the on-board camera and flash of a mobile device. The sequence of captures are used to reconstruct high quality normal maps using near-light photometric stereo algorithms, which are of comparable quality to conventional photometric stereo. We demonstrate 3D surface reconstructions with SfS on different materials and scales. Moreover, the mobile SfS technique can be used "in the wild" so that 3D scans may be performed in their natural environment, eliminating the need for transport to a laboratory setting. With the elegant design and low cost, we believe our Mobile SfS can greatly benefit the conservation community by providing a userfriendly and cost-effective solution for 3D surface scanning.

关键词： 3D Surface Shape Reconstruction Photometric Stereo image-based modeling Reflectance Transformation Imaging Scale-invariant Feature Transform Near-Light Position Calibration

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AN image-based modeling EXPERIENCE ABOUT SOCIAL FACILITIES, BUILT DURING THE FASCIST PERIOD IN MIDDLE ITALY 4

AN IMAGE-BASED MODELING EXPERIENCE ABOUT SOCIAL FACILITIES, ...

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4th ISPRS International Workshop 3D-ARCH - 3D Virtual Reconstruction and Visualization of Complex Architectures

作者： Rossi, D. Univ Camerino Scuola Architettura & Design E Vittoria I-62032 Camerino Italy

The main focus of this article is to explain a teaching activity. This experience follows a research aimed to testing innovative systems for formal and digital analysis of architectural building. In particular, the field of investigation is the analytical drawing. An analytical draw allows to develope an interpretative and similar models of reality;these models are built using photomodeling techniques and are designed to re-mTite modern and contemporary architecture. The typology of the buildings surveyed belong to a cultural period, called Modern Movement, historically placed between the two world wars. The Modern Movement aimed to renew existing architectural principle and to a functional redefinition of the same one. In Italy these principles arrived during the Fascist period. Heritage made up of public social buildings (case del Balilla, GIL., recreation center...) built during the fascist period in middle Italy is remarkable for quantity and in many cases for architectural quality. This kind of buildings arc composed using pure shapes: large cube (gyms) alternate with long rectangular block containing offices creates compositions made of big volumes and high towers. These features are perfectly suited to the needs of a surveying process by photomodeling where the role of photography is central and where there is the need to identify certain and easily distinguishable points on all picture, leaning on the edges of the volume or lininig on the texture discontinuity. The goal is the documentation to preserve and to develop buildings and urban complexes of modern architecture, directed to encourage an artistic preservation.

关键词： modeling Reconstruction Visualization Heritage documentation image-based modeling Survey

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Interactive 3D content modeling for Digital Earth

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VISUAL COMPUTER 2016年第10期32卷 1293-1309页

作者： Samavati, Faramarz Runions, Adam Univ Calgary Dept Comp Sci Calgary AB Canada Univ Calgary Dept Comp Sci Graph Jungle Comp Graph Lab Calgary AB Canada

Digital Earth is a global reference model for integrating, processing and visualizing geospatial datasets. In this reference model, various data-types, including Digital Elevation Models (DEM) and imagery (orthophotos), are universally and openly available for the entire globe. However, 3D content such as detailed terrains with features, man-made structures, 3D water bodies and 3D vegetation are not commonly available in Digital Earth. In this paper, we present an interactive system for the rapid creation and integration of these types of 3D content to augment Digital Earth. The inputs to our system include available data sources, such as DEM and imagery information depicting landscapes and urban environments. The proposed system employs sketch-based and image-assisted tools to support interactive creation of textured 3D content. For adding terrain features visible in orthophotos, and also the basin of water bodies, we use a multiscale least square surface fitting to generate an adaptive triangular subdivision. For modeling forests and vegetation, we use image-based techniques and take advantage of visible regions and colors of forests in orthophotos. For 3D man-made structures, starting from a single photograph, we provide a simple image-assisted sketching tool to extract these objects, correct for perspective distortion and place them into desired locations.

关键词： Digital Earth Computer graphics Interactive modeling Sketch-based modeling Subdivision surfaces image-based modeling

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Evaluation of a high-resolution patient-specific model of the electrically stimulated cochlea

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JOURNAL OF MEDICAL IMAGING 2017年第2期4卷 025003-025003页

作者： Cakir, Ahmet Dwyer, Robert T. Noble, Jack H. Vanderbilt Univ Dept Elect Engn & Comp Sci 221 Kirkland Hall Nashville TN 37235 USA Vanderbilt Univ Med Ctr Dept Hearing & Speech Sci Nashville TN USA

Cochlear implants (CIs) are surgically implanted medical devices used to treat individuals with severeto-profound sensorineural hearing loss. Although these devices have been remarkably successful at restoring audibility, many patients experience poor outcomes. Our group has developed the first image-guided CI programming technique where the electrode positions are found in CT images and used to estimate neural activation patterns, which is unique information that audiologists can use to define patient-specific processor settings. Currently, neural activation is estimated using only the distance from each electrode to the neural activation sites, which might be less accurate than using high-resolution electro-anatomical models (EAMs) to perform physics-based estimations of neural activation. We propose a patient-customized EAM approach where the EAM is spatially and electrically adapted to a patient-specific configuration. Spatial adaptation is done through nonrigid registration of the model with the patient CT image. Electrical adaptation is done by adjusting tissue resistivity parameters, so the intracochlear voltage distributions predicted by the model best match those directly measured for the patient via their implant. We found that our approach, demonstrated for N = 7 patients, results in mean percent differences between direct and simulated measurements of voltage distributions of 10.9%. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE).

关键词： cochlear implant image-based modeling image-guided cochlear implant programming

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Differential impact of local stiffening and narrowing on hemodynamics in repaired aortic coarctation: an FSI study

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MEDICAL & BIOLOGICAL ENGINEERING & COMPUTING 2016年第2-3期54卷 497-510页

作者： Taelman, Liesbeth Bols, Joris Degroote, Joris Muthurangu, Vivek Panzer, Joseph Vierendeels, Jan Segers, Patrick Univ Ghent Fac Engn & Architecture IBiTech bioMMeda iMinds Med IT B-9000 Ghent Belgium Univ Ghent Fac Engn & Architecture Dept Flow Heat & Combust Mech Sint Pietersnieuwstr 41 B-9000 Ghent Belgium London Great Ormond St Hosp Children UCL Inst Child Hlth Ctr Cardiovasc MR Great Ormond St London WC1N 3JH England Ghent Univ Hosp Paediat Cardiol De Pintelaan 185 B-9000 Ghent Belgium

Even after successful treatment of aortic coarctation, a high risk of cardiovascular morbidity and mortality remains. Uncertainty exists on the factors contributing to this increased risk among which are the presence of (1) a residual narrowing leading to an additional resistance and (2) a less distensible zone disturbing the buffer function of the aorta. As the many interfering factors and adaptive physiological mechanisms present in vivo prohibit the study of the isolated impact of these individual factors, a numerical fluid-structure interaction model is developed to predict central hemodynamics in coarctation treatment. The overall impact of a stiffening on the hemodynamics is limited, with a small increase in systolic pressure (up to 8 mmHg) proximal to the stiffening which is amplified with increasing stiffening and length. A residual narrowing, on the other hand, affects the hemodynamics significantly. For a short segment (10 mm), the combination of a stiffening and narrowing (coarctation index 0.5) causes an increase in systolic pressure of 58 mmHg, with 31 mmHg due to narrowing and an additional 27 mmHg due to stiffening. For a longer segment (25 mm), an increase in systolic pressure of 50 mmHg is found, of which only 9 mmHg is due to stiffening.

关键词： Fluid-structure interaction Stent End-toend anastomosis image-based modeling

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A crystal plasticity-based study of the relationship between microstructure and ultra-high-cycle fatigue life in nickel titanium alloys

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INTERNATIONAL JOURNAL OF FATIGUE 2016年第Part1期91卷 183-194页

作者： Moore, John A. Frankel, Dana Prasannavenkatesan, Rajesh Domel, August G. Olson, Gregory B. Liu, Wing Kam Lawrence Livermore Natl Lab POB 808 Livermore CA 94551 USA Northwestern Univ Dept Mat Sci & Engn Evanston IL 60208 USA QuesTek Inovat LLC 1820 Ridge Ave Evanston IL 60201 USA Northwestern Univ Dept Mech Engn Evanston IL 60208 USA Harvard Univ Sch Engn & Appl Sci Cambridge MA 02138 USA

Nickel Titanium (NiTi) alloys are often used in biomedical devices where failure due to mechanical fatigue is common. For other alloy systems, computational models have proven an effective means of determining the relationship between microstructural features and fatigue life. This work will extend the subset of those models which were based on crystal plasticity to examine the relationship between microstructure and fatigue life in NiTi alloys. It will explore the interaction between a spherical inclusion and the material's free surface along with several NiTi microstructures reconstructed from 3D imaging. This work will determine the distance at which the free surface interacts with an inclusion and the effect of applied strain of surface-inclusion interaction. The effects of inclusion-inclusion interaction, matrix voiding, and matrix strengthening are explored and ranked with regards to their influence on fatigue life. Published by Elsevier Ltd.

关键词： Microstructures Finite elements Surface effects image-based modeling

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From video to computation of biological fluid-structure interaction problems

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THEORETICAL AND COMPUTATIONAL FLUID DYNAMICS 2016年第1-2期30卷 41-66页

作者： Dillard, Seth I. Buchholz, James H. J. Udaykumar, H. S. Univ Iowa Dept Biomed Engn Seamans Ctr Engn Arts & Sci Iowa City IA 52242 USA Univ Iowa Dept Mech & Ind Engn Seamans Ctr Engn Arts & Sci Iowa City IA 52242 USA

This work deals with the techniques necessary to obtain a purely Eulerian procedure to conduct CFD simulations of biological systems with moving boundary flow phenomena. Eulerian approaches obviate difficulties associated with mesh generation to describe or fit flow meshes to body surfaces. The challenges associated with constructing embedded boundary information, body motions and applying boundary conditions on the moving bodies for flow computation are addressed in the work. The overall approach is applied to the study of a fluid-structure interaction problem, i.e., the hydrodynamics of swimming of an American eel, where the motion of the eel is derived from video imaging. It is shown that some first-blush approaches do not work, and therefore, careful consideration of appropriate techniques to connect moving images to flow simulations is necessary and forms the main contribution of the paper. A combination of level set-based active contour segmentation with optical flow and image morphing is shown to enable the image-to-computation process.

关键词： Moving boundaries Level sets Optical flow Morphing image-based modeling Cartesian grid methods

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A New Approach to image-based Estimation of Food Volume

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ALGORITHMS 2017年第2期10卷 66-66页

作者： Hassannejad, Hamid Matrella, Guido Ciampolini, Paolo De Munari, Ilaria Mordonini, Monica Cagnoni, Stefano Univ Parma Dipartimento Ingn Informaz I-43124 Parma Italy

A balanced diet is the key to a healthy lifestyle and is crucial for preventing or dealing with many chronic diseases such as diabetes and obesity. Therefore, monitoring diet can be an effective way of improving people's health. However, manual reporting of food intake has been shown to be inaccurate and often impractical. This paper presents a new approach to food intake quantity estimation using image-based modeling. The modeling method consists of three steps: firstly, a short video of the food is taken by the user's smartphone. From such a video, six frames are selected based on the pictures' viewpoints as determined by the smartphone's orientation sensors. Secondly, the user marks one of the frames to seed an interactive segmentation algorithm. Segmentation is based on a Gaussian Mixture Model alongside the graph-cut algorithm. Finally, a customized image-based modeling algorithm generates a point-cloud to model the food. At the same time, a stochastic object-detection method locates a checkerboard used as size/ground reference. The modeling algorithm is optimized such that the use of six input images still results in an acceptable computation cost. In our evaluation procedure, we achieved an average accuracy of 92% on a test set that includes images of different kinds of pasta and bread, with an average processing time of about 23 s.

关键词： automatic diet monitoring image analysis interactive segmentation image-based modeling volume estimation

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Numerical analysis of the thermal behaviors of cellular concrete

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COMPUTERS AND CONCRETE 2016年第3期18卷 319-336页

作者： She, Wei Zhao, Guotang Yang, Guotao Jiang, Jinyang Cao, Xiaoyu Du, Yi Southeast Univ Jiangsu Key Lab Construct Mat Nanjing 211189 Jiangsu Peoples R China China Railway Corp Beijing 100844 Peoples R China Jiangsu Inst Bldg Sci Co LTD Nanjing 210008 Jiangsu Peoples R China Univ Dundee Div Civil Engn Concrete Technol Unit Dundee DD1 4HN Scotland

In this study, both two-and three-dimensional (2D and 3D) finite-volume-based models were developed to analyze the heat transfer mechanisms through the porous structures of cellular concretes under steady-state heat transfer conditions and to investigate the differences between the 2D and 3D modeling results. The 2D and 3D reconstructed pore networks were generated from the microstructural information measured by 3D images captured by X-ray computerized tomography (X-CT). The computed effective thermal conductivities based on the 2D and 3D calculations performed on the reconstructed porous structures were found to be nearly identical to those evaluated from the 2D cross-sectional images and the 3D X-CT images, respectively. In addition, the 3D computed effective thermal conductivity was found to agree better with the measured values, in comparison with the 2D reconstruction and real cross-sectional images. Finally, the thermal conductivities computed for different reconstructed porous 3D structures of cellular concretes were compared with those obtained from 2D computations performed on 2D reconstructed structures. This comparison revealed the differences between 2D and 3D image-based modeling. A correlation was thus derived between the results of the 3D and 2D models.

关键词： Finite volume method (FVM) Effective thermal conductivity (ETC) image-based modeling cellular concrete Guarded hot-plate method (GHP)

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