Papers by Keyword: 3D Reconstruction

Abstract: The micro and nano structures of porous material have strong influence on their transfer properties such as porosity, permeability, tortuosity and adsorption isotherm curves. In the construction and building material field, these properties are strongly related to hydro and thermal comfort, due to the fact that heat and mass transfer mechanisms are determined by the micro porous structure. In the present work, we aim to predict heat and mass transfer on such micro-nano structured materials, with a statistical quantification method that is extracted from morphology aspect. A large range of the pore size (from 20nm to 1mm) is covered and investigated by the multiple approaches, including FIB-SEM, X-Ray Tomography, and MIP (Mercury Intrusion Porosimetry). The 3D view of pore structures is obtained in concrete, as well as their size distribution, and pore zones. A reconstruct of 3D view of pore networks is extracted, with the spatial resolution of 20 nm/pixel. A global view of multiple testing methods and the corresponding size ranges are drawn to summarize the multi-scale approaches, for a potential further understanding of relationship between porous structure and thermal-hydro properties.

Abstract: Babbitt alloys are the most commonly used bearing materials for low speed diesel engines due to their excellent attributes. An understanding of microstructures in these alloys is important, especially quantifying microstructure in 3D. In this study, we used serial sectioning technique to reconstruct 3D microstructure of tin-based Babbitt lining of bimetallic bearing made by centrifugal casting based on medical software Mimics. The morphologies and volume fraction of hard phase particles and α-Sn matrix were obtained. The volume fraction of the reconstructed microstructures was verified by the area fraction of the metallographic sections, which proved a higher reliability of 3D reconstruction. The results of 3D microstructural characterization and analysis will enable a comprehensive understanding the structure–property relationships of these materials.

Abstract: Technological advances in the digital camera industry and computing resources make the use of photogrammetry a very fast, low-cost, contactless and non-destructive technique. It can represent a good alternative to obtain 3D information for monitoring and conservation of cultural heritage assets, especially where it is not possible to use 3D laser scanners and also in situations where areas to be inspected are not easily accessible [1]. Resolution generally depends on the number of images, their quality and the level of overlap between them, as well as hardware and software capabilities. Starting from 2D aerial or terrestrial photographic images, photogrammetry allows to reconstruct a 3D model in the form of a "point cloud" and also to derive accurate 3D measurements of large architectural elements.This paper is about stereo-photogrammetric scanning by drone performed by MENCI software s.r.l. aimed at the definition of the state of conservation of the “Bridge of the Towers” in Spoleto and its long term preservation without building scaffoldings. It was performed within the RoMA (Resilience enhancement of a Metropolitan Area) project, through an agreement between the “Italian National Agency for New Technologies, Energy and Sustainable Economic Development” (ENEA) and the “Italian Ministry of Cultural Heritage and Activities” (MIBACT).Photogrammetric scanning and FE modelling were applied within the project together with many other monitoring techniques in order to assess the bridge cracks pattern and its structural health by a multidisciplinary approach that allows their mutual validation [2].As one of the most important problems in the use of photogrammetric 3D reconstruction is the considerable demand in terms of hardware and software resources for images processing and data storage, thanks to the HPC (High Performance Computing) resources provided by the CRESCO infrastructure (Research Computational Centre on Complex Systems), it was possible to analyse and process a large amount of high-resolution photos in order to detect the crack pattern and to assess the actual damage state to be monitored over time [3].

Abstract: AISI 441 ferritic stainless steel is a good candidate for metallic interconnects in solid oxide fuel cells (SOFCs). The minor elements Ti and Nb are used to stabilize the ferritic matrix and also to reduce creep by a combination of solid solution strengthening and precipitation of intermetallic Laves phase particles along the grain boundaries. However their influence on the oxidation behavior is not well understood. This study focuses on the early stages oxidation (from 4 to 24 h) at 800 °C of AISI 441 under 5% H₂O in O₂. A relatively smooth micro-crystallized oxide scale and Ti, Nb containing nodules are observed. The internal microstructure of these objects is studied by FIB tomography which allows computing cross sectional views in any direction of interest. FIB study reveals a complex microstructure and a development strongly linked to the presence of niobium and/or titanium in the substrate.

Abstract: With the rapid development of medical imaging technology, computer graphics and visualization technologies, virtual endoscopy technology emerged. It mainly includes 2D medical image segmentation, 3D image reconstruction, path planning and virtual roaming. However, the path planning of virtual endoscopy has become one of the obstacles in this field due to the high irregularity of the nasopharyngeal anatomy structure. In this study, the nasopharynx including meatus nasi, pharyngeal canal, maxillary sinus, frontal sinus, sphenoid sinus, and ethmoid sinus is segmented and 3D reconstructed using MR images. The key technology of virtual endoscopy - center path planning algorithm is implemented based on distance transform. Also, two improved algorithms of center path planning are proposed. One is the selection algorithm of branch path and the other is the extraction algorithm for complex path based on human-computer interaction. These two improved algorithms can not only allow the traditional path planning algorithm to handle multiple branching structure but make roaming path to start at any point. Our experimental results satisfied the needs of clinical practice.

Abstract: Stress distributions that occur in the free end second premolar tooth and its root form dental implant replacement were evaluated using finite element method. In the modelling process, 3D reconstructions were performed. Instead of doing it manually, the 3D reconstruction in this paper was done using cone beam computed tomography (CBCT) scanning process. The 3D reconstruction method used in this paper, is considerably faster than the traditional manual 3D reconstruction method. In order to mimic the actual biting force, static load of 200 N was modelled in the vertical direction parallel to the long axis of the tooth which is placed on bite contact at second premolars and dental implant crown. The stress result on root form dental implant is generally higher than the stress on the natural free end second premolar tooth. The stress concentration locations on root form dental implant were also found and will be used in the future to improve the design of root form dental implant.

Abstract: Paper approaches some characteristics and bioengineering applications of a handheld depth sensor for low-cost 3D scanning and reconstruction. The Kinect depth sensor used in this work was launched on June 2009 and was based around a gaming webcam peripheral. The Kinect sensor uses a structured light technique in order to develop real-time 3D surfaces. The 3D model of anatomic surface may have a lot of bioengineering applications. Some observations and comparisons are presented in connection with the scanning and 3D reconstruction of different anatomic surfaces.

Abstract: Ultrasonic phased array imaging detection technology combinating the focused beam and array probe movement can get powerful test information. It has been widely used in the steel butt weld detection. For making up the limitations of 2D view, in this paper,we used one-dimensional linear array probe, got 2D slice view data obtained by phased array ultrasonic S-scan, through software programming algorithm to realize 3D reconstruction of steel butt weld typical defects. Experiment shows that it can display more intuitive performance of the defects in space. Revealing a better shape, size and orientation information. Providing a reference for the final evaluation of the defect.

Abstract: This study claims an algorithm of calibration which is executed on the basis of projection matrix. This algorithm directly estimates intrinsic parameter on the basis of rotation matrix’s unitary orthogonality combined with Cholesky decomposition from the obtained projection matrix. Then, false is excluded by rotation matrix’s determinant constraints, and ultimately, camera location and orientation matrix are obtained and estimated parameters are optimized with the minimum error of reprojection residual being cost function. This algorithm is taken under a pinhole camera model and can calibrate the camera from single view with variable focal length. Both simulation data and true image experiments have proved the feasibility and robustness of this algorithm.

Abstract: the rheo-squeeze casting (Rheo-SQC) combining the rheocasting and the SQC was developed, in which semi-solid slurry was produced by the low superheat pouring with a shearing field (LSPSF) process. The three dimensional morphology of the primary α-Al phase and the rest spacing of slurry prepared by LSPSF process have been reconstructed and visualized, and the microstructures of squeeze cast A356 alloy have been obtained. Based on the three dimensional microstructure reconstructed, their three dimensional characterizations such as solid volume fraction, equivalent diameter of the extracted primary α-Al phase were measured and calculated, and the microstructures of cross section of squeeze cast product were investigated.