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Sexton, Paul. "3D velocity-depth model building using surface seismic and well data." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4824/.
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The objective of this work was to develop techniques that could be used to rapidly build a three-dimensional velocity-depth model of the subsurface, using the widest possible variety of data available from conventional seismic processing and allowing for moderate structural complexity. The result is a fully implemented inversion methodology that has been applied successfully to a large number of diverse case studies. A model-based inversion technique is presented and shown to be significantly more accurate than the analytical methods of velocity determination that dominate industrial practice. The inversion itself is based around two stages of ray-tracing. The first takes picked interpretations in migrated-time and maps them into depth using a hypothetical interval velocity field; the second checks the validity of this field by simulating fully the kinematics of seismic acquisition and processing as accurately as possible. Inconsistencies between the actual and the modelled data can then be used to update the interval velocity field using a conventional linear scheme. In order to produce a velocity-depth model that ties the wells, the inversion must include anisotropy. Moreover, a strong correlation between anisotropy and lithology is found. Unfortunately, surface seismic and well-tie data are not usually sufficient to uniquely resolve all the anisotropy parameters; however, the degree of non-uniqueness can be measured quantitatively by a resolution matrix which demonstrates that the model parameter trade-offs are highly dependent on the model and the seismic acquisition. The model parameters are further constrained by introducing well seismic traveltimes into the inversion. These introduce a greater range of propagation angles and reduce the non- uniqueness.
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BIAGIOLI, ELISA. "Depth-averaged and 3D Finite Volume numerical models for viscous fluids, with application to the simulation of lava flows." Doctoral thesis, Università degli studi di Genova, 2021. http://hdl.handle.net/11567/1057651.
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This Ph.D. project was initially born from the motivation to contribute to the depth-averaged and 3D modeling of lava flows. Still, we can frame the work done in a broader and more generalist vision. We developed two models that may be used for generic viscous fluids, and we applied efficient numerical schemes for both cases, as explained in the following.
The new solvers simulate free-surface viscous fluids whose temperature changes are due to radiative, convective, and conductive heat exchanges. A temperature-dependent viscoplastic model is used for the final application to lava flows. Both the models behind the solvers were derived from mass, momentum, and energy conservation laws. Still, one was obtained by following the depth-averaged model approach and the other by the 3D model approach. The numerical schemes adopted in both our models belong to the family of finite volume methods, based on the integral form of the conservation laws. This choice of methods family is fundamental because it allows the creation and propagation of discontinuities in the solutions and enforces the conservation properties of the equations.
We propose a depth-averaged model for a viscous fluid in an incompressible and laminar regime with an additional transport equation for a scalar quantity varying horizontally and a variable density that depends on such transported quantity. Viscosity and non-constant vertical profiles for the velocity and the transported quantity are assumed, overtaking the classic shallow-water formulation. The classic formulation bases on several assumptions, such as the fact that the vertical pressure distribution is hydrostatic, that the vertical component of the velocity can be neglected, and that the horizontal velocity field can be considered constant with depth because the classic formulation accounts for non-viscous fluids. When the vertical shear is essential, the last assumption is too restrictive, so it must relax, producing a modified momentum equation in which a coefficient, known as the Boussinesq factor, appears in the advective term. The spatial discretization method we employed is a modified version of the central-upwind scheme introduced by Kurganov and Petrova in 2007 for the classical shallow water equations. This method is based on a semi-discretization of the computational domain, is stable, and, being a high-order method, has a low numerical diffusion. For the temporal discretization, we used an implicit-explicit Runge-Kutta technique discussed by Russo in 2005 that permits an implicit treatment of the stiff terms. The whole scheme is proved to preserve the positivity of flow thickness and the stationary steady-states. Several numerical experiments validate the proposed method, show the incidence on the numerical solutions of shape coefficients introduced in the model and present the effects of the viscosity-related parameters on the final emplacement of a lava flow.
Our 3D model describes the dynamics of two incompressible, viscous, and immiscible fluids, possibly belonging to different phases. Being interested in the final application of lava flows, we also have an equation for energy that models the thermal exchanges between the fluid and the environment. We implemented this model in OpenFOAM, which employs a segregated strategy and the Finite Volume Methods to solve the equations. The Volume of Fluid (VoF) technique introduced by Hirt and Nichols in 1981 is used to deal with the multiphase dynamics (based on the Interphase Capturing strategy), and hence a new transport equation for the volume fraction of one phase is added. The challenging effort of maintaining an accurate description of the interphase between fluids is solved by using the Multidimensional Universal Limiter for Explicit Solution (MULES) method (described by Marquez Damian in 2013) that implements the Flux-Corrected Transport (FCT) technique introduced by Boris and Book in 1973, proposing a mix of high and low order schemes. The choice of the framework to use for any new numerical code is crucial.
Our contribution consists of creating a new solver called interThermalRadConvFoam in the OpenFOAM framework by modifying the already existing solver interFoam (described by Deshpande et al. in 2012). Finally, we compared the results of our simulations with some benchmarks to evaluate the performances of our model.
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Sankoh, Hiroshi. "Object Extraction for Virtual-viewpoint Video Synthesis." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/200465.
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Hua, Xiaoben, and Yuxia Yang. "A Fusion Model For Enhancement of Range Images." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2203.
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In this thesis, we would like to present a new way to enhance the “depth map” image which is called as the fusion of depth images. The goal of our thesis is to try to enhance the “depth images” through a fusion of different classification methods. For that, we will use three similar but different methodologies, the Graph-Cut, Super-Pixel and Principal Component Analysis algorithms to solve the enhancement and output of our result. After that, we will compare the effect of the enhancement of our result with the original depth images. This result indicates the effectiveness of our methodology.Room 401, No.56, Lane 21, Yin Gao Road, Shanghai, China
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Diskin, Yakov. "Dense 3D Point Cloud Representation of a Scene Using Uncalibrated Monocular Vision." University of Dayton / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1366386933.
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Stålberg, Martin. "Reconstruction of trees from 3D point clouds." Thesis, Uppsala universitet, Avdelningen för systemteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-316833.
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The geometrical structure of a tree can consist of thousands, even millions, of branches, twigs and leaves in complex arrangements. The structure contains a lot of useful information and can be used for example to assess a tree's health or calculate parameters such as total wood volume or branch size distribution. Because of the complexity, capturing the structure of an entire tree used to be nearly impossible, but the increased availability and quality of particularly digital cameras and Light Detection and Ranging (LIDAR) instruments is making it increasingly possible. A set of digital images of a tree, or a point cloud of a tree from a LIDAR scan, contains a lot of data, but the information about the tree structure has to be extracted from this data through analysis. This work presents a method of reconstructing 3D models of trees from point clouds. The model is constructed from cylindrical segments which are added one by one. Bayesian inference is used to determine how to optimize the parameters of model segment candidates and whether or not to accept them as part of the model. A Hough transform for finding cylinders in point clouds is presented, and used as a heuristic to guide the proposals of model segment candidates. Previous related works have mainly focused on high density point clouds of sparse trees, whereas the objective of this work was to analyze low resolution point clouds of dense almond trees. The method is evaluated on artificial and real datasets and works rather well on high quality data, but performs poorly on low resolution data with gaps and occlusions.
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Grankvist, Ola. "Recognition and Registration of 3D Models in Depth Sensor Data." Thesis, Linköpings universitet, Datorseende, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-131452.
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Object Recognition is the art of localizing predefined objects in image sensor data. In this thesis a depth sensor was used which has the benefit that the 3D pose of the object can be estimated. This has applications in e.g. automatic manufacturing, where a robot picks up parts or tools with a robot arm. This master thesis presents an implementation and an evaluation of a system for object recognition of 3D models in depth sensor data. The system uses several depth images rendered from a 3D model and describes their characteristics using so-called feature descriptors. These are then matched with the descriptors of a scene depth image to find the 3D pose of the model in the scene. The pose estimate is then refined iteratively using a registration method. Different descriptors and registration methods are investigated. One of the main contributions of this thesis is that it compares two different types of descriptors, local and global, which has seen little attention in research. This is done for two different scene scenarios, and for different types of objects and depth sensors. The evaluation shows that global descriptors are fast and robust for objects with a smooth visible surface whereas the local descriptors perform better for larger objects in clutter and occlusion. This thesis also presents a novel global descriptor, the CESF, which is observed to be more robust than other global descriptors. As for the registration methods, the ICP is shown to perform most accurately and ICP point-to-plane more robust.
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Semmens, Stephen Bradley. "An Engineering Geological Investigation of the Seismic Subsoil Classes in the Central Wellington Commercial Area." Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/4287.
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The city of Wellington has a high population concentration and lies within a geologically active landscape at the southern end of the North Island, New Zealand. Wellington has a high seismic risk due to its close proximity to several major fault systems, with the active Wellington Fault located in the north-western central city. Varying soil depth and properties in combination with the close proximity of active faults mean that in a large earthquake rupture event, ground shaking amplification is expected to occur in Thorndon, Te Aro and around the waterfront.
This thesis focuses on the area bounded by Thorndon Overbridge in the north, Wellington Hospital in the south, Kelburn in the west, and Oriental Bay in the east. It includes many of the major buildings and infrastructural elements located within the central Wellington commercial area. The main objectives were to create an electronic database which allows for convenient access to all available data within the study area, to create a 3D geological model based upon this data, and to define areas of different seismic subsoil class and depth to rock within the study area at a scale that is useful for preliminary geotechnical analysis (1:5,000.
Borelogs from 1025 holes with accompanying geological and geotechnical data obtained from GNS Science and Tonkin & Taylor were compiled into a database, together with the results from SPAC microtremor testing at 12 sites undertaken specifically for this study. This thesis discusses relevant background work and defines the local Wellington geology.
A 3D geological model of the central Wellington commercial area, along with ten ArcGIS maps including surficial, depth to bedrock, site period, Vs30, ground shaking amplification hazard and site class (NZS 1170.5:2004) maps were created. These outputs show that a significant ground shaking amplification risk is posed on the city, with the waterfront, Te Aro and Thorndon areas most at risk.
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Hasnat, Md Abul. "Unsupervised 3D image clustering and extension to joint color and depth segmentation." Thesis, Saint-Etienne, 2014. http://www.theses.fr/2014STET4013/document.
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L'accès aux séquences d'images 3D s'est aujourd'hui démocratisé, grâce aux récentes avancées dans le développement des capteurs de profondeur ainsi que des méthodes permettant de manipuler des informations 3D à partir d'images 2D. De ce fait, il y a une attente importante de la part de la communauté scientifique de la vision par ordinateur dans l'intégration de l'information 3D. En effet, des travaux de recherche ont montré que les performances de certaines applications pouvaient être améliorées en intégrant l'information 3D. Cependant, il reste des problèmes à résoudre pour l'analyse et la segmentation de scènes intérieures comme (a) comment l'information 3D peut-elle être exploitée au mieux ? et (b) quelle est la meilleure manière de prendre en compte de manière conjointe les informations couleur et 3D ? Nous abordons ces deux questions dans cette thèse et nous proposons de nouvelles méthodes non supervisées pour la classification d'images 3D et la segmentation prenant en compte de manière conjointe les informations de couleur et de profondeur. A cet effet, nous formulons l'hypothèse que les normales aux surfaces dans les images 3D sont des éléments à prendre en compte pour leur analyse, et leurs distributions sont modélisables à l'aide de lois de mélange. Nous utilisons la méthode dite « Bregman Soft Clustering » afin d'être efficace d'un point de vue calculatoire. De plus, nous étudions plusieurs lois de probabilités permettant de modéliser les distributions de directions : la loi de von Mises-Fisher et la loi de Watson. Les méthodes de classification « basées modèles » proposées sont ensuite validées en utilisant des données de synthèse puis nous montrons leur intérêt pour l'analyse des images 3D (ou de profondeur). Une nouvelle méthode de segmentation d'images couleur et profondeur, appelées aussi images RGB-D, exploitant conjointement la couleur, la position 3D, et la normale locale est alors développée par extension des précédentes méthodes et en introduisant une méthode statistique de fusion de régions « planes » à l'aide d'un graphe. Les résultats montrent que la méthode proposée donne des résultats au moins comparables aux méthodes de l'état de l'art tout en demandant moins de temps de calcul. De plus, elle ouvre des perspectives nouvelles pour la fusion non supervisée des informations de couleur et de géométrie. Nous sommes convaincus que les méthodes proposées dans cette thèse pourront être utilisées pour la classification d'autres types de données comme la parole, les données d'expression en génétique, etc. Elles devraient aussi permettre la réalisation de tâches complexes comme l'analyse conjointe de données contenant des images et de la paroleAccess to the 3D images at a reasonable frame rate is widespread now, thanks to the recent advances in low cost depth sensors as well as the efficient methods to compute 3D from 2D images. As a consequence, it is highly demanding to enhance the capability of existing computer vision applications by incorporating 3D information. Indeed, it has been demonstrated in numerous researches that the accuracy of different tasks increases by including 3D information as an additional feature. However, for the task of indoor scene analysis and segmentation, it remains several important issues, such as: (a) how the 3D information itself can be exploited? and (b) what is the best way to fuse color and 3D in an unsupervised manner? In this thesis, we address these issues and propose novel unsupervised methods for 3D image clustering and joint color and depth image segmentation. To this aim, we consider image normals as the prominent feature from 3D image and cluster them with methods based on finite statistical mixture models. We consider Bregman Soft Clustering method to ensure computationally efficient clustering. Moreover, we exploit several probability distributions from directional statistics, such as the von Mises-Fisher distribution and the Watson distribution. By combining these, we propose novel Model Based Clustering methods. We empirically validate these methods using synthetic data and then demonstrate their application for 3D/depth image analysis. Afterward, we extend these methods to segment synchronized 3D and color image, also called RGB-D image. To this aim, first we propose a statistical image generation model for RGB-D image. Then, we propose novel RGB-D segmentation method using a joint color-spatial-axial clustering and a statistical planar region merging method. Results show that, the proposed method is comparable with the state of the art methods and requires less computation time. Moreover, it opens interesting perspectives to fuse color and geometry in an unsupervised manner. We believe that the methods proposed in this thesis are equally applicable and extendable for clustering different types of data, such as speech, gene expressions, etc. Moreover, they can be used for complex tasks, such as joint image-speech data analysis
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Nosjean, Nicolas. "Management et intégration des risques et incertitudes pour le calcul de volumes de roches et de fluides au sein d’un réservoir, zoom sur quelques techniques clés d’exploration Integrated Post-stack Acoustic Inversion Case Study to Enhance Geological Model Description of Upper Ordovicien Statics : from imaging to interpretation pitfalls and an efficient way to overcome them Improving Upper Ordovician reservoir characterization - an Algerian case study Tracking Fracture Corridors in Tight Gas Reservoirs : An Algerian Case Study Integrated sedimentological case study of glacial Ordovician reservoirs in the Illizi Basin, Algeria A Case Study of a New Time-Depth Conversion Workflow Designed for Optimizing Recovery Proper Systemic Knowledge of Reservoir Volume Uncertainties in Depth Conversion Integration of Fault Location Uncertainty in Time to Depth Conversion Emergence of edge scenarios in uncertainty studies for reservoir trap analysis Enhancing geological model with the use of Spectral Decomposition - A case study of a prolific stratigraphic play in North Viking Graben, Norway Fracture corridor identification through 3D multifocusing to improve well deliverability, an Algerian tight reservoir case study Geological Probability Of Success Assessment for Amplitude-Driven Prospects, A Nile Delta Case Study." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASS085.
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En tant que géoscientifique dans le domaine de l’Exploration pétrolière et gazière depuis une vingtaine d’années, mes fonctions professionnelles m’ont permis d’effectuer différents travaux de recherche sur la thématique de la gestion des risques et des incertitudes. Ces travaux de recherche se situent sur l’ensemble de la chaîne d’analyse Exploration, traitant de problématiques liées à l’acquisition et au traitement sismique, jusqu’au placement optimal de forages d’exploration. Un volet plus poussé de mes travaux s’est orienté sur la gestion des incertitudes géophysiques en Exploration pétrolière, là où l’incertitude est la plus importante et paradoxalement la moins travaillée.On peut regrouper mes travaux de recherche en trois grands domaines qui suivent les grandes étapes du processus Exploration : le traitement sismique, leur interprétation, et enfin l'analyse et l'extraction des différentes incertitudes qui vont nous permettre de calculer les volumes d’hydrocarbures en place et récupérables, ainsi que l’analyse de ses risques associés. L’ensemble des travaux de recherche ont été appliqués avec succès sur des cas d’études opérationnelles. Après avoir introduit quelques notions générales et détaillé les grandes étapes du processus Exploration et leur lien direct avec ces problématiques, je présenterai quatre grands projets de recherche sur un cas d’étude algérienIn the last 20 years, I have been conducting various research projects focused on the management of risks and uncertainties in the petroleum exploration domain. The various research projects detailed in this thesis are dealing with problematics located throughout the whole Exploration and Production chain, from seismic acquisition and processing, until the optimal exploration to development wells placement. Focus is made on geophysical risks and uncertainties, where these problematics are the most pronounced and paradoxically the less worked in the industry. We can subdivide my research projects into tree main axes, which are following the hydrocarbon exploration process, namely: seismic processing, seismic interpretation thanks to the integration with various well informations, and eventually the analysis and extraction of key uncertainties, which will be the basis for the optimal calculation of in place and recoverable volumes, in addition to the associated risk analysis on a given target structure. The various research projects that are detailed in this thesis have been applied successfully on operational North Africa and North Sea projects. After introducing risks and uncertainty notions, we will detail the exploration process and the key links with these issues. I will then present four major research projects with their theoretical aspects and applied case study on an Algerian asset
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Yeh, Yen-Ting, and 葉彥廷. "On Generating Vehicle Surrounding Images Based on Depth-Adaptive 3D Model." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/43490970816309709013.
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碩士國立臺灣大學
資訊網路與多媒體研究所
102
Driving assistance systems help drivers to avoid car accidents by provid-ing warning signals or visual cues of surrounding situations. Instead of the fixed bird’s-eye view monitoring proposed in many previous works, we de-veloped a real-time vehicle surrounding monitoring system, ”Angel Eye”, that can assist drivers to perceive the vehicle surrounding situations more easily. In our system, four fisheye cameras are mounted around a vehicle. To inte-grate these four fisheye camera views, we firstly use fisheye camera calibra-tion method to dewarp the captured images into perspective projection ones. Then, we calculated the camera intrinsic parameters and homography trans-form matrix to get the camera extrinsic parameters. To stitch these dewarpped images, we projected undistorted images into a 3D hybrid projection model and finally the images of the selected viewpoint are rendered. However, the unknown position of foreground obstacles would cause some visual noises, like image distortion of objects or ghost effect. So we add depth camera into previous system to obtain the depth information of foreground obstacles. The proposed 3D model can be adjusted based on the distance between vehicle and foreground obstacles. The depth-adaptive model can fa-cilitate the rendering of vehicle surroundings in a more realistic and correct way.
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Lin, Ping-hsien, and 林秉賢. "3D Model Retrieval Based on Projection Depth Maps and Moment Invariants." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/93475608681812372590.
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碩士國立臺南大學
數位學習科技學系碩士班
98
In this study, we purpose a new content-based approach to retrieving 3D models from a database, based on projection depth maps and moment invariants. Our system can be divided into offline and online stages. In the offline stage, the location and size of each model is normalized first. For each normalized model and its circumscribed dodecahedron, sixty projection depth maps are obtained at the twenty vertices and with three directions. Afterward, 2D and 3D moment invariants are computed for each map and constitute two feature vectors respectively. In the online stage, a user can choose a 3D model as the query. Our system can match the query with each 3D model in the database and reply the most similar models within 1 second. If a user inputs a binary image as the query, our system can extract 2D moment invariants from the query and perform partial matching with each 3D model. A logarithmic searching strategy is proposed to improve the efficiency of partial matching. Accordingly, the 3D models with through similar projection maps will be retrieved. Experimental results show that the proposed approach is effective and efficient.
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HUNG, CHIEN-YU, and 洪千喻. "Using Handheld Depth Sensor for 3D Model Reconstruction and Augmented Reality Application." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/m2fvhr.
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碩士國立臺北大學
不動產與城鄉環境學系
107
In recent years, 3D modeling technology has developed rapidly, and the application has become increasingly diverse, such as virtual reality and augment reality. While the acquisition of 3d information, such as the passive sensing of photogrammetry and multi-angle image modeling based on computer vision, and the active sensing of LiDAR etc., have their own advantages and disadvantages, like the modeling of passive sensing is difficult in the area with insufficient feature points, and the high-precision active sensing instrument is expensive. This study uses Occipital Structure Sensor as the test instrument, which is an active infrared ray range finder and can be attached to the mobile device. The product has corresponding development software, which is both convenient and economical. However, it is necessary to understand the 3D model precision constructed by Structure Sensor, in order to understand the applicable fields, limitations and problems. In this study, the volume value and the distance of feature points were calculated as the 3D accuracy evaluation method, and a 3D point cloud was obtained by using Skannect software. After reconstruction of the point cloud model, the volume and the distance of feature points were calculated using The Maximum Likelihood Estimation Sample Consensus (MLESAC) to extract the model with geometric significance (square body, sphere and cylinder) . The experiment shows that the 3D model volume error of the Structure Sensor construction is in the range of 1.69% ~ 5.30%, and the feature point distance error is 1.09% ~ 2.64%.This method is convenient to obtain 3D information, and also provides another 3D modeling choice for texture-less object in the future. In terms of the application of the 3D model, this study established the augmented reality application of teaching level’s operational process through Google ARCore and game development engine Unity. Through this research process, the level model was built and the point-select sliding function of each part of the level was designed to provide simulation operation experience and improve the application of 3D modeling.
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Yeh, Ming-han, and 葉名翰. "Efficient 3D Video Coding for Depth Image Using D-NOSE Model-based Optimal Modification." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/9hx67r.
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碩士國立臺灣科技大學
資訊工程系
100
Depth distortions caused by depth video coding which is required for storage and transmission considerations may cause geometry changes in view synthesis. However, for the depth value of each pixel, there exists a range within which no geometry changes will be observed. We propose an efficient 3D video coding which, for each pixel in the macroblock, modifies, without inducing any geometry change, the depth value to minimize the residual. Experiment results show that the proposed method substantially reduces the bitrate while preserving the quality of the rendered image.
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Liu, Han-wen, and 劉瀚文. "2D-to-3D Conversion for a Single Image Based on Background Depth Model Estimation." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/18242030438995254678.
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Nguyen, Trong Nguyen. "Analysis of 3D human gait reconstructed with a depth camera and mirrors." Thèse, 2019. http://hdl.handle.net/1866/23439.
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L'évaluation de la démarche humaine est l'une des composantes essentielles dans les soins de santé. Les systèmes à base de marqueurs avec plusieurs caméras sont largement utilisés pour faire cette analyse. Cependant, ces systèmes nécessitent généralement des équipements spécifiques à prix élevé et/ou des moyens de calcul intensif. Afin de réduire le coût de ces dispositifs, nous nous concentrons sur un système d'analyse de la marche qui utilise une seule caméra de profondeur. Le principe de notre travail est similaire aux systèmes multi-caméras, mais l'ensemble de caméras est remplacé par un seul capteur de profondeur et des miroirs. Chaque miroir dans notre configuration joue le rôle d'une caméra qui capture la scène sous un point de vue différent. Puisque nous n'utilisons qu'une seule caméra, il est ainsi possible d'éviter l'étape de synchronisation et également de réduire le coût de l'appareillage.
Notre thèse peut être divisée en deux sections: reconstruction 3D et analyse de la marche. Le résultat de la première section est utilisé comme entrée de la seconde. Notre système pour la reconstruction 3D est constitué d'une caméra de profondeur et deux miroirs. Deux types de capteurs de profondeur, qui se distinguent sur la base du mécanisme d'estimation de profondeur, ont été utilisés dans nos travaux. Avec la technique de lumière structurée (SL) intégrée dans le capteur Kinect 1, nous effectuons la reconstruction 3D à partir des principes de l'optique géométrique. Pour augmenter le niveau des détails du modèle reconstruit en 3D, la Kinect 2 qui estime la profondeur par temps de vol (ToF), est ensuite utilisée pour l'acquisition d'images. Cependant, en raison de réflections multiples sur les miroirs, il se produit une distorsion de la profondeur dans notre système. Nous proposons donc une approche simple pour réduire cette distorsion avant d'appliquer les techniques d'optique géométrique pour reconstruire un nuage de points de l'objet 3D.
Pour l'analyse de la démarche, nous proposons diverses alternatives centrées sur la normalité de la marche et la mesure de sa symétrie. Cela devrait être utile lors de traitements cliniques pour évaluer, par exemple, la récupération du patient après une intervention chirurgicale. Ces méthodes se composent d'approches avec ou sans modèle qui ont des inconvénients et avantages différents. Dans cette thèse, nous présentons 3 méthodes qui traitent directement les nuages de points reconstruits dans la section précédente. La première utilise la corrélation croisée des demi-corps gauche et droit pour évaluer la symétrie de la démarche, tandis que les deux autres methodes utilisent des autoencodeurs issus de l'apprentissage profond pour mesurer la normalité de la démarche.The problem of assessing human gaits has received a great attention in the literature since gait analysis is one of key components in healthcare. Marker-based and multi-camera systems are widely employed to deal with this problem. However, such systems usually require specific equipments with high price and/or high computational cost. In order to reduce the cost of devices, we focus on a system of gait analysis which employs only one depth sensor. The principle of our work is similar to multi-camera systems, but the collection of cameras is replaced by one depth sensor and mirrors. Each mirror in our setup plays the role of a camera which captures the scene at a different viewpoint. Since we use only one camera, the step of synchronization can thus be avoided and the cost of devices is also reduced. Our studies can be separated into two categories: 3D reconstruction and gait analysis. The result of the former category is used as the input of the latter one. Our system for 3D reconstruction is built with a depth camera and two mirrors. Two types of depth sensor, which are distinguished based on the scheme of depth estimation, have been employed in our works. With the structured light (SL) technique integrated into the Kinect 1, we perform the 3D reconstruction based on geometrical optics. In order to increase the level of details of the 3D reconstructed model, the Kinect 2 with time-of-flight (ToF) depth measurement is used for image acquisition instead of the previous generation. However, due to multiple reflections on the mirrors, depth distortion occurs in our setup. We thus propose a simple approach for reducing such distortion before applying geometrical optics to reconstruct a point cloud of the 3D object. For the task of gait analysis, we propose various alternative approaches focusing on the problem of gait normality/symmetry measurement. They are expected to be useful for clinical treatments such as monitoring patient's recovery after surgery. These methods consist of model-free and model-based approaches that have different cons and pros. In this dissertation, we present 3 methods that directly process point clouds reconstructed from the previous work. The first one uses cross-correlation of left and right half-bodies to assess gait symmetry while the other ones employ deep auto-encoders to measure gait normality.
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Su, Che-Chun. "Applied statistical modeling of three-dimensional natural scene data." Thesis, 2014. http://hdl.handle.net/2152/24878.
Full textAbstract:
Natural scene statistics (NSS) have played an increasingly important role in both our understanding of the function and evolution of the human vision system, and in the development of modern image processing applications. Because depth/range, i.e., egocentric distance, is arguably the most important thing a visual system must compute (from an evolutionary perspective), the joint statistics between natural image and depth/range information are of particular interest. However, while there exist regular and reliable statistical models of two-dimensional (2D) natural images, there has been little work done on statistical modeling of natural luminance/chrominance and depth/disparity, and of their mutual relationships. One major reason is the dearth of high-quality three-dimensional (3D) image and depth/range database. To facilitate research progress on 3D natural scene statistics, this dissertation first presents a high-quality database of color images and accurately co-registered depth/range maps using an advanced laser range scanner mounted with a high-end digital single-lens reflex camera. By utilizing this high-resolution, high-quality database, this dissertation performs reliable and robust statistical modeling of natural image and depth/disparity information, including new bivariate and spatial oriented correlation models. In particular, these new statistical models capture higher-order dependencies embedded in spatially adjacent bandpass responses projected from natural environments, which have not yet been well understood or explored in literature. To demonstrate the efficacy and effectiveness of the advanced NSS models, this dissertation addresses two challenging, yet very important problems, depth estimation from monocular images and no-reference stereoscopic/3D (S3D) image quality assessment. A Bayesian depth estimation framework is proposed to consider the canonical depth/range patterns in natural scenes, and it forms priors and likelihoods using both univariate and bivariate NSS features. The no-reference S3D image quality index proposed in this dissertation exploits new bivariate and correlation NSS features to quantify different types of stereoscopic distortions. Experimental results show that the proposed framework and index achieve superior performance to state-of-the-art algorithms in both disciplines.text
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Hu, Shang-Jen, and 胡尚仁. "Controlling depth perception for rendering stereoscopic 3D models." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/46338257466247793428.
Full textAbstract:
碩士國立臺灣科技大學
色彩與照明科技研究所
101
Recently, the development of the stereo display technology progresses fast. However, less three-dimensional software provides quality stereoscopic render. In using this kind of software, users sometimes have discomfort experience when viewing stereoscopic 3D models. So, producing quality stereoscopic 3D technology becomes an important issue. Usually, user adjusts the camera position by him or herself when viewing stereoscopic models. Amateur will provoke eye fatigue and feel uncomfortable under improper camera parameters. Therefore, we test the effect of different visual stereo camera’s parameters and parallax distributions. We will propose a stereoscopic camera adjustment algorithm for improving visual comfort and preference of stereoscopic images. In this paper, we carry out a virtual stereoscopic camera system, which has different positions, convergence angles, and parallax distributions, in OpenGL. When users use this system, the vast majority of the parallax will be constrained in the safe range. It is helpful to improve 3D visual comfort and make 3D display popular.
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Vitale, Andrea. "Multiscale inversion of potential fields: from 1D to 3D depth-weighted models." Tesi di dottorato, 2019. http://www.fedoa.unina.it/12726/1/vitale_andrea_31.pdf.
Full textAbstract:
We developed two different approaches of inversion of potential fields:
- A method for 1D inversion of potential fields.
- A method for 2D and 3D self-constrained depth weighted inversion of inhomogeneous potential fields.
Both methods are based on a multiscale approach, that is they involve use of data at different scales or altitudes. These particular approaches bring some benefits.
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Leite, Inês de Sousa Caldas Rodrigues. "Recognition and 6 DoF Pose Estimation of 3D Models in Depth Sensor Data." Master's thesis, 2018. https://repositorio-aberto.up.pt/handle/10216/116531.
Full text
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Leite, Inês de Sousa Caldas Rodrigues. "Recognition and 6 DoF Pose Estimation of 3D Models in Depth Sensor Data." Dissertação, 2018. https://repositorio-aberto.up.pt/handle/10216/116531.
Full text
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Pattani, Varun Paresh. "Understanding cell death response to gold nanoparticle-mediated photothermal therapy in 2D and 3D in vitro tumor models for improving cancer therapy." 2013. http://hdl.handle.net/2152/23106.
Full textAbstract:
Gold nanoparticles, a class of plasmonic nanoparticle, have increasingly been explored as an imaging and therapeutic agent to treat cancer due to their characteristic surface plasmon resonance phenomenon and penchant for tumor accumulation. Photothermal therapy has been shown as a promising cancer treatment by delivering heat specifically to the tumor site via gold nanoparticles. In this study, we demonstrate that gold nanorod (GNR)-mediated photothermal therapy can be more effective through the understanding of cell death mechanisms. By targeting GNRs to various cellular localizations, we explored the association of GNR localization with cell death pathway response to photothermal therapy. Furthermore, we compared the 2D monolayer experiments with 3D in vitro tumor models, multicellular tumor spheroids (MCTS), to mimic the structure of in vivo tumors. With MCTS, we evaluated the cell death response with GNRs distributed only on the periphery, as seen in typical in vivo studies, and distributed evenly throughout the tumor.
We demonstrated that GNR localization influences the cell death response to photothermal therapy by showing the power threshold necessary to induce significant apoptotic and necrotic increases was lower for internalized GNRs than membrane-bound GNRs. Furthermore, apoptosis was found to increase with increasing laser power until the necrotic threshold and decreased above it, as necrosis became the dominant cell death pathway response. A similar trend was revealed with the 3D MCTS; however, the overall cell death percentages were lower, most likely due to the upregulated cell repair response and varied GNR distributions due to the presence of cell-cell and cell-matrix interactions. Furthermore, the uniformly distributed GNRs induced more apoptosis and necrosis than GNRs located in the MCTS periphery. In conclusion, we quantitatively analyzed the cell death pathway response to GNR-mediated photothermal therapy to establish that it has some dependence on GNR localization and distribution to gain a more thorough understanding of this response for photothermal therapy optimization.text
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Villa, C., Jo Buckberry, C. Cattaneo, B. Frohlich, and N. Lynnerup. "Quantitative analysis of the morphological changes of the pubic symphyseal face and the auricular surface and implications for age at death estimation." 2015. http://hdl.handle.net/10454/7176.
Full textAbstract:
YesAge estimation methods are often based on the age-related morphological changes of the auricular surface and the pubic bone. In this study, a mathematical approach to quantify these changes has been tested analyzing the curvature variation on 3D models from CT and laser scans. The sample consisted of the 24 Suchey–Brooks (SB) pubic bone casts, 19 auricular surfaces from the Buckberry and Chamberlain (BC) “recording kit” and 98 pelvic bones from the Terry Collection (Smithsonian Institution). Strong and moderate correlations between phases and curvature were found in SB casts (ρ 0.60–0.93) and BC “recording kit” (ρ 0.47–0.75), moderate and weak correlations in the Terry Collection bones (pubic bones: ρ 0.29–0.51, auricular surfaces: ρ 0.33–0.50) but associated with large individual variability and overlap of curvature values between adjacent decades. The new procedure, requiring no expert judgment from the operator, achieved similar correlations that can be found in the classic methods.