Image-based Modeling Techniques Research Articles

Numerical Study on the Morphology and Mechanical Role of Healthy and Osteoporotic Vertebral Trabecular Bone

This study presents a numerical methodology to clarify the morphology of complex trabecular network architecture in human lumbar vertebra by means of the new post-processing technique for calculated microscopic stress by the homogenization method. Micro-CT image-based modeling technique is used and careful but intuitive and easy-to-use method for microstructure model, in other words region of interest (ROI), is also presented. The macroscopic homogenized properties that include not only the Young’s moduli but also shear moduli could explain the difference of morphology between healthy and osteoporotic bones. This paper focuses on the change of degree of anisotropy. Then, the microscopic stress under three basis load cases was analyzed. In this analysis, the homogenization method has a merit in the computational cost. The trabeculae are classified into eight groups from the viewpoint of load bearing function against three loading conditions in the proposed post-processing of numerical results. It contributes to the understanding of the mechanical role of trabecular bone in vertebra. The primary trabecular bone that has been supposed to support the self-weight and secondary bone that connects the primary bone are successfully visualized. The discussion on the mechanical role of plate-like trabecular bone in the load path network system is also highlighted.

Multiscale prediction of crack density and crack length accumulation in trabecular bone based on neural networks and finite element simulation

In this paper, a novel multiscale algorithm to simulate accumulation of trabecular bone crack density and crack length at macroscopic scale during cyclic loading is developed. The method is based on finite element analysis and neural network computation to link mesoscopic (trabecular level) and macroscopic (whole femur) scales. The finite element calculation is performed at the macroscopic level and a trained neural network incorporated into the finite element code Abaqus is employed as a numerical device to perform the local mesoscopic computation. Based on a set of mesoscale simulations of representative volume elements obtained by digital image-based modeling technique using µ-CT and voxel finite element, a neural network is trained to approximate the local finite element responses. The input data for the artificial neural network are the applied stress, the stress orientation and the cycle frequency. The output data are the averaged crack density and crack length at a given site of the bone. Copyright © 2010 John Wiley & Sons, Ltd.

Volumetric stereo and silhouette fusion for image-based modeling

This paper presents a volumetric stereo and silhouette fusion algorithm for acquiring high quality models from multiple calibrated photographs. Our method is based on computing and merging depth maps. Different from previous methods of this category, the silhouette information is also applied in our algorithm to recover the shape information on the textureless and occluded areas. The proposed algorithm starts by computing visual hull using a volumetric method in which a novel projection test method is proposed for visual hull octree construction. Then, the depth map of each image is estimated by an expansion-based approach that returns a 3D point cloud with outliers and redundant information. After generating an oriented point cloud from stereo by rejecting outlier, reducing scale, and estimating surface normal for the depth maps, another oriented point cloud from silhouette is added by carving the visual hull octree structure using the point cloud from stereo to restore the textureless and occluded surfaces. Finally, Poisson Surface Reconstruction approach is applied to convert the oriented point cloud both from stereo and silhouette into a complete and accurate triangulated mesh model. The proposed approach has been implemented and the performance of the approach is demonstrated on several real data sets, along with qualitative comparisons with the state-of-the-art image-based modeling techniques according to the Middlebury benchmark.

Image-Based Modeling of Blood Flow and Vessel Wall Dynamics: Applications, Methods and Future Directions

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.

Current progress in patient-specific modeling.

We present a survey of recent advancements in the emerging field of patient-specific modeling (PSM). Researchers in this field are currently simulating a wide variety of tissue and organ dynamics to address challenges in various clinical domains. The majority of this research employs three-dimensional, image-based modeling techniques. Recent PSM publications mostly represent feasibility or preliminary validation studies on modeling technologies, and these systems will require further clinical validation and usability testing before they can become a standard of care. We anticipate that with further testing and research, PSM-derived technologies will eventually become valuable, versatile clinical tools.

Physically guided liquid surface modeling from videos

We present an image-based reconstruction framework to model real water scenes captured by stereoscopic video. In contrast to many image-based modeling techniques that rely on user interaction to obtain high-quality 3D models, we instead apply automatically calculated physically-based constraints to refine the initial model. The combination of image-based reconstruction with physically-based simulation allows us to model complex and dynamic objects such as fluid. Using a depth map sequence as initial conditions, we use a physically based approach that automatically fills in missing regions, removes outliers, and refines the geometric shape so that the final 3D model is consistent to both the input video data and the laws of physics. Physically-guided modeling also makes interpolation or extrapolation in the space-time domain possible, and even allows the fusion of depth maps that were taken at different times or viewpoints. We demonstrated the effectiveness of our framework with a number of real scenes, all captured using only a single pair of cameras.

A study on compression-induced morphological changes of nonwoven fibrous materials

Pore size is a characteristic parameter that is often defined for fibrous materials used in industrial applications. While there exist many available studies on the pore size distribution of different fibrous materials, the influence of compression load on pore size distribution has not been studied well. Studying the behavior of fibrous materials under compression is important especially because in many applications these materials are subjected to some degree of compression during use. In this work, we present a novel image-based modeling technique to study the changes in the pore size distribution of a fibrous material exposed to compressive load. This was made possible by building a miniature compression cell, and imaging the structure of a hydroentangled fabric under varying levels of compression. The 3D images obtained with Digital Volumetric Imaging were utilized to study the pore size distribution of the material and develop an empirical correlation as a function of compressive stress for these structures. This new correlation indicates that the mean pore diameter of a nonwoven material decreases exponentially with increasing the compressive stress.

Reverse engineering of architectural buildings based on a hybrid modeling approach

This article presents a set of theoretical reflections and technical demonstrations that constitute a new methodological base for the architectural surveying and representation using computer graphics techniques. The problem we treated relates to three distinct concerns: the surveying of architectural objects, the construction and the semantic enrichment of their geometrical models, and their handling for the extraction of dimensional information. A hybrid approach to 3D reconstruction is described. This new approach combines range-based modeling and image-based modeling techniques; it integrates the concept of architectural feature-based modeling. To develop this concept set up a first process of extraction and formalization of architectural knowledge based on the analysis of architectural treaties is carried on. Then, the identified features are used to produce a template shape library. Finally the problem of the overall model structure and organization is addressed.

Multi-Scale Stress Analysis of Trabecular Bone Considering Trabeculae Morphology and Biological Apatite Crystallite Orientation

This paper presents the multi-scale stress analysis of trabecular bone by the homogenization method bridging nano-micro-macro scales. Three-dimensional microstructure of trabeculae is obtained by the X-ray CT and the image-based modeling technique. Biological apatite (BAp) crystallite orientation is considered in the microstructure model by means of the anisotropic mechanical properties. The c-axis of BAp is set up as the maximum principal stress direction under the long term macroscopic stress condition. These properties are automatically assigned to each voxel element. To determine appropriately the microstructure model, the trabeculae morphology is analyzed and quantified as the trabecular density distribution. The proposed method is applied to pig's femur. It was revealed by the morphology analysis and homogenized macroscopic properties that the trabecular bone has plate-like characteristics. The predicted anisotropic level of the macroscopic properties was quantitatively coincident with the measured value by the X-ray diffraction analysis.

A new approach to image-based realistic architecture modeling with featured solid library

To overcome restrictions of present modeling techniques, and to approach quick and convenient 3D architecture modeling, we present a realistic modeling system on the basis of a featured solid library. The system incorporates reference library techniques to build up realistic models from a single image. In our approach, parameterized solid components are mapped to 2D featured projection graphs on image plane, and matching features of all component graphs with the resource image results in 3D realistic scene, whether complex or irregular. Besides, a suite of texture toolkit is implemented to rectify flaws of texture mapping and to enhance modeling reality. Our approach works feasibly and robustly with single-vision images taken from arbitrary view angles, and the efficiency of our approach is proved in systematic modeling experiments. As our approach complemented image-based modeling techniques in construction CAD and digital city systems, it could be of popular use in relevant modeling software.

Detailed 3D reconstruction of large-scale heritage sites with integrated techniques

Many cultural heritage applications require 3D reconstruction of real-world objects and scenes. Over the past few years, it has become increasingly common to use 3D digitization and modeling for this purpose. This is mainly due to advances in laser-scanning techniques, 3D modeling software, image-based modeling techniques, computer power, and virtual reality. Our approach integrates several technologies based on our experience over more than a decade of trying to accurately and completely model large-scale heritage monuments and sites. Using both interactive and automatic techniques, we can model a highly detailed structure or site at various levels of detail. We use image-based modeling for basic shape and structural elements, and laser scanning for fine details and sculpted surfaces. To present the site in its proper context, we use image-based rendering for landscapes and surroundings. To apply this approach, we created hundreds of models from sites all over the world for documentation, walk-through movies, and interactive visualization. The results were compelling and encouraging.

Detailed 3D reconstruction of large-scale heritage sites with integrated techniques

Many cultural heritage applications require 3D reconstruction of real-world objects and scenes. Over the past few years, it has become increasingly common to use 3D digitization and modeling for this purpose. This is mainly due to advances in laser-scanning techniques, 3D modeling software, image-based modeling techniques, computer power, and virtual reality. Our approach integrates several technologies based on our experience over more than a decade of trying to accurately and completely model large-scale heritage monuments and sites. Using both interactive and automatic techniques, we can model a highly detailed structure or site at various levels of detail. We use image-based modeling for basic shape and structural elements, and laser scanning for fine details and sculpted surfaces. To present the site in its proper context, we use image-based rendering for landscapes and surroundings. To apply this approach, we created hundreds of models from sites all over the world for documentation, walk-through movies, and interactive visualization. The results were compelling and encouraging.

MESO-SCOPIC NUMERICAL ANALYSIS OF CONCRETE STRUCTURES BY A MODIFIED LATTICE MODEL

Realistic simulation of the mechanical behavior of concrete and reinforced concrete structures is performed by using a lattice type numerical model. Five different types of lattice members with simple constitutive models are introduced for mortar, coarse aggregate, steel, aggregate-mortar interface and steel-concrete interface. The meso-scopic morphology of concrete, which can be realized by the image-based geometry modeling technique, is taken into account. By the incorporation of the accurate meso-scopic morphology into the lattice type numerical modeling, the cracking behavior induced by the meso-scopic heterogeneities has been successfully captured.

Microstructure-based stress analysis and evaluation for porous ceramics by homogenization method with digital image-based modeling

Multi-scale analysis using the asymptotic homogenization method is becoming a matter of concern for microstructural design and analysis of advanced heterogeneous materials. One of the problems is the lack of the experimental verification of the multi-scale analysis. Hence, it is applied to the porous alumina with needle-like pores to compare the predicted homogenized properties with the experimental result. The complex and random microstructure was modeled three-dimensionally with the help of the digital image-based modeling technique. An appropriate size of the unit microstructure model was investigated. The predicted elastic properties agreed quite well with the measured values. Next, a four-point bending test was simulated and finally the microscopic stress distribution was predicted. However, it was very hard to evaluate the calculated microscopic stress quantitatively. Therefore, a numerical algorithm to help understanding the three-dimensional and complex stress distribution in the random porous microstructure is proposed. An original histogram display of the stress distribution is shown to be effective to evaluate the stress concentration in the porous materials.

Three-Dimensional Microstructural Modeling and Homogenization of Porous Alumina with Needle-Like Pores

In the development of functional ceramics, the study on the relation between the macroscopic properties and the microstructures has been a critical issue. However, it has not been made clear by many experimental works. On the other hand, this paper takes the computational mechanics approach using the homogenization method. To model the very complex microstructure architecture three-dimensionally, the image-based modeling technique is employed. A porous alumina with needle-like random pores with 3.1% porosity ratio is studied in this paper. The effect of the location of extracting the unit cell and its size on the homogenized elastic constants is investigated. Then, the predicted values were compared with the measured ones. As a result, a unit cell region expressed by one million voxel elements with 2µm resolution provides very accurate prediction regardless of the location of the unit cell in the random microstructures. The error between the numerical prediction and the measurement is only 1%.

Multi-Scale Analysis and Microscopic Stress Evaluation for Ceramics Considering the Random Microstructures

A multi-scale computational method using the homogenization method is applied to the stress analysis of ceramics considering the random and complex microstructure three-dimensionally. The main purpose of this paper is to propose a numerical method to understand quantitatively the microscopic stress distribution in the random microstructure especially for porous ceramics. The voxel mesh is used to model the microstructure automatically with the help of the image-based modeling technique. In the analysis of porous alumina with needle-like random pores, the distance from the nearest pore is measured for all the voxel elements, which is plotted with the histogram of the microscopic stress distribution. This is of great help to study the relation between the stress concentration and the pore geometry and dispersion.

Projective Texture Mapping with Full Panorama

Projective texture mapping is used to project a texture map onto scene geometry. It has been used in many applications, since it eliminates the assignment of fixed texture coordinates and provides a good method of representing synthetic images or photographs in image-based rendering. But conventional projective texture mapping has limitations in the field of view and the degree of navigation because only simple rectangular texture maps can be used. In this work, we propose the concept of panoramic projective texture mapping (PPTM). It projects cubic or cylindrical panorama onto the scene geometry. With this scheme, any polygonal geometry can receive the projection of a panoramic texture map, without using fixed texture coordinates or modeling many projective texture mapping. For fast real-time rendering, a hardware-based rendering method is also presented. Applications of PPTM include panorama viewer similar to QuicktimeVR and navigation in the panoramic scene, which can be created by image-based modeling techniques. Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Viewing Algorithms; I.3.7 [Computer Graphics]: Color, Shading, Shadowing, and Texture

Three-Dimensional Microstructural Modeling and Homogenization of Porous Alumina with Needle-Like Pores.

In the development of functional ceramics, the study on the relation between the macroscopic properties and the microstructures has been a critical issue. However, it has not been made clear by many experimental works. On the other hand, this paper takes the computational mechanics approach using the homogenization method. To model the very complex microstructure architecture three-dimensionally, the image-based modeling technique is employed. A porous alumina with needle-like random pores with 3.1% porosity ratio is studied in this paper. The effect of the location of extracting the unit cell and its size on the homogenized elastic constants is investigated. Then, the predicted values were compared with the measured ones. As a result, a unit cell region expressed by one million voxel elements with 2μm resolution provides very accurate prediction regardless of the location of the unit cell in the random microstructures. The error between the numerical prediction and the measurement is only 1%.

Multi-scale Analysis and Microscopic Stress Evaluation for Ceramics Considering the Random Microstructures.

A multi-scale computational method using the homogenization method is applied to the stress analysis of ceramics considering the random and complex microstructure three-dimensionally. The main purpose of this paper is to propose a numerical method to understand quantitatively the microscopic stress distribution in the random microstructure especially for porous ceramics. The voxel mesh is used to model the microstructure automatically with the help of the image-based modeling technique. In the analysis of porous alumina with needle-like random pores, the distance from the nearest pore is measured for all the voxel elements, which is plotted with the histogram of the microscopic stress distribution. This is of great help to study the relation between the stress concentration and the pore geometry and dispersion.

非均質材料のためのマルチスケール解析モデリングについて

The homogenization method is examined in conjunction with the method of representative volume elements (RVE). When the digital image-based modeling technique enables us to model the complex geometry of microstructures, the boundaries of unit cells fail to have the geometric periodicity Nonetheles, the effective moduli are reasonably estimated by the homogenition with periodic boundary conditions. This fact is justified theoretically and simulated along with the notion of homogenization convergence. In adition to the convegence of effective moduli with respect to the size of RVEs, the microscopic mechanical behaviors are examined in comparison with macroscopic ones. Thus, the multiscale nature of the analysis modeling by the asymptotic homogenization is characterized by carrying out a series of linear and nonliinear numerical analyses.