Dissertations / Theses on the topic 'Structure- Motion'
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Scheffler, Carl. "Articulated structure from motion." Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=init_2988_1177923873.
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The structure from motion (SfM) problem is that of determining 3-dimensional (3D) information of a scene from sequences of 2-dimensional (2D) images [59]. This information consists of object shape and motion and relative camera motion. In general, objects may undergo complex non-rigid motion and may be occluded by other objects or themselves. These aspects make the general SfM problem under-constrained and the solution subject to missing or incomplete data.
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Svensson, Fredrik. "Structure from Forward Motion." Thesis, Linköpings universitet, Bildbehandling, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-60136.
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This master thesis investigates the difficulties of constructing a depth map using one low resolution grayscale camera mounted in the front of a car. The goal is to produce a depth map in real-time to assist other algorithms in the safety system of a car. This has been shown to be difficult using the evaluated combination of camera position and choice of algorithms. The main problem is to estimate an accurate optical flow. Another problem is to handle moving objects. The conclusion is that the implementations, mainly triangulation of corresponding points tracked using a Lucas Kanade tracker, provide information of too poor quality to be useful for the safety system of a car.I detta examensarbete undersöks svårigheterna kring att skapa en djupbild från att endast använda en lågupplöst gråskalekamera monterad framtill i en bil. Målet är att producera en djupbild i realtid som kan nyttjas i andra delar av bilens säkerhetssystem. Detta har visat sig vara svårt att lösa med den undersökta kombinationen av kameraplacering och val av algoritmer. Det huvudsakliga problemet är att räkna ut ett noggrant optiskt flöde. Andra problem härrör från objekt som rör på sig. Slutsatsen är att implementationerna, mestadels triangulering av korresponderande punktpar som följts med hjälp av en Lucas Kanade-följare, ger resultat av för dålig kvalitet för att vara till nytta för bilens säkerhetssystem.
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Wong, Kwan-Yee Kenneth. "Structure and motion from silhouettes." Thesis, University of Cambridge, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.621379.
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Zucchelli, Marco. "Optical Flow Based Structure from Motion." Doctoral thesis, KTH, Numerical Analysis and Computer Science, NADA, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3377.
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Orthey, Andreas. "Exploiting structure in humanoid motion planning." Phd thesis, Toulouse, INPT, 2015. http://oatao.univ-toulouse.fr/14685/1/orthey.pdf.
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If humanoid robots should work along with humans and should be able to solve repetitive tasks, we need to enable them with a skill to autonomously plan motions. Motion planning is a longstanding core problem in robotics, and while its algorithmic foundation has been studied in depth, motion planning is still an NP-hard problem lacking efficient solutions. We want to open up a new perspective on the problem by highlighting its structure: the behavior of the robot, the mechanical system of the robot, and the environment of the robot. We will investigate the hypothesis that each structural component can be exploited to create more efficient motion planning algorithms. We present three algorithms exploiting structure, based on geometrical and topological arguments: first, we exploit the behavior of a walking robot by studying the feasibility of footstep transitions. The resulting algorithm is able to plan footsteps avoiding up to 60 objects on a 6 square meters planar surface. Second, we exploit the mechanical system of a humanoid robot by studying the linear linkage structures of its arms and legs. We introduce the concept of an irreducible motion, which is a completeness-preserving dimensionality reduction technique. The resulting algorithm is able to find motions in narrow environments, where previous sampling-based methods could not be applied. Third, we exploit the environment by reasoning about the topological structure of contact transitions. We show that analyzing the environment is an efficient method to precompute relevant information for efficient motion planning. Based on those results, we come to the conclusion that exploiting structure is an essential component of efficient motion planning. It follows that any humanoid robot, who wants to act efficiently in the real world, needs to be able to understand and to exploit structure.
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Hedborg, Johan. "Motion and Structure Estimation From Video." Doctoral thesis, Linköpings universitet, Datorseende, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-76904.
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Digital camera equipped cell phones were introduced in Japan in 2001, they quickly became popular and by 2003 outsold the entire stand-alone digital camera market. In 2010 sales passed one billion units and the market is still growing. Another trend is the rising popularity of smartphones which has led to a rapid development of the processing power on a phone, and many units sold today bear close resemblance to a personal computer. The combination of a powerful processor and a camera which is easily carried in your pocket, opens up a large eld of interesting computer vision applications. The core contribution of this thesis is the development of methods that allow an imaging device such as the cell phone camera to estimates its own motion and to capture the observed scene structure. One of the main focuses of this thesis is real-time performance, where a real-time constraint does not only result in shorter processing times, but also allows for user interaction. In computer vision, structure from motion refers to the process of estimating camera motion and 3D structure by exploring the motion in the image plane caused by the moving camera. This thesis presents several methods for estimating camera motion. Given the assumption that a set of images has known camera poses associated to them, we train a system to solve the camera pose very fast for a new image. For the cases where no a priory information is available a fast minimal case solver is developed. The solver uses ve points in two camera views to estimate the cameras relative position and orientation. This type of minimal case solver is usually used within a RANSAC framework. In order to increase accuracy and performance a renement to the random sampling strategy of RANSAC is proposed. It is shown that the new scheme doubles the performance for the ve point solver used on video data. For larger systems of cameras a new Bundle Adjustment method is developed which are able to handle video from cell phones. Demands for reduction in size, power consumption and price has led to a redesign of the image sensor. As a consequence the sensors have changed from a global shutter to a rolling shutter, where a rolling shutter image is acquired row by row. Classical structure from motion methods are modeled on the assumption of a global shutter and a rolling shutter can severely degrade their performance. One of the main contributions of this thesis is a new Bundle Adjustment method for cameras with a rolling shutter. The method accurately models the camera motion during image exposure with an interpolation scheme for both position and orientation. The developed methods are not restricted to cellphones only, but is rather applicable to any type of mobile platform that is equipped with cameras, such as a autonomous car or a robot. The domestic robot comes in many avors, everything from vacuum cleaners to service and pet robots. A robot equipped with a camera that is capable of estimating its own motion while sensing its environment, like the human eye, can provide an eective means of navigation for the robot. Many of the presented methods are well suited of robots, where low latency and real-time constraints are crucial in order to allow them to interact with their environment.Virtual Photo Set (VPS)
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Örjehag, Erik. "Unsupervised Learning for Structure from Motion." Thesis, Linköpings universitet, Datorseende, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-173731.
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Perception of depth, ego-motion and robust keypoints is critical for SLAM andstructure from motion applications. Neural networks have achieved great perfor-mance in perception tasks in recent years. But collecting labeled data for super-vised training is labor intensive and costly. This thesis explores recent methodsin unsupervised training of neural networks that can predict depth, ego-motion,keypoints and do geometric consensus maximization. The benefit of unsuper-vised training is that the networks can learn from raw data collected from thecamera sensor, instead of labeled data. The thesis focuses on training on imagesfrom a monocular camera, where no stereo or LIDAR data is available. The exper-iments compare different techniques for depth and ego-motion prediction fromprevious research, and shows how the techniques can be combined successfully.A keypoint prediction network is evaluated and its performance is comparedwith the ORB detector provided by OpenCV. A geometric consensus network isalso implemented and its performance is compared with the RANSAC algorithmin OpenCV. The consensus maximization network is trained on the output of thekeypoint prediction network. For future work it is suggested that all networkscould be combined and trained jointly to reach a better overall performance. Theresults show (1) which techniques in unsupervised depth prediction are most ef-fective, (2) that the keypoint predicting network outperformed the ORB detector,and (3) that the consensus maximization network was able to classify outlierswith comparable performance to the RANSAC algorithm of OpenCV.
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Hakl, Henri. "Structure-from-motion for enclosed environments." Thesis, Link to the online version, 2007. http://hdl.handle.net/10019.1/1195.
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Rautenbach, Pieter Albertus. "Facial Feature Reconstruction using Structure from Motion." Thesis, Link to the online version, 2005. http://hdl.handle.net/10019/1340.
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Ji, Hui. "A holistic approach to structure from motion." College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3807.
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Thesis (Ph. D.) -- University of Maryland, College Park, 2006.Thesis research directed by: Computer Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Van, Wyk Barry-Michael Morne. "Verifying stereo vision using structure from motion." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/3017.
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Thesis (MScEng (Mathematical Sciences. Applied Mathematics))--Stellenbosch University, 2008.The medical radiation treatment facility at iThemba Labs requires a precise and robust patient positioning system. The current system makes use of an accurately calibrated multi-camera stereophotogrammetry (SPG) setup that is vulnerable to physical disruptions that invalidate system calibration. The task in this thesis is to design a vision system that can be used to verify the correct operation of the SPG system. We propose an unscented Kalman filter (UKF) based structure from motion (SFM) system for this purpose. Our SFM system does not rely on calibration information used by the SPG system and provides accurate reconstruction for verification purposes. The system is critically evaluated against a set of synthetic and real motion sequences.
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Svensson, Niclas. "Structure from Motion with Unstructured RGBD Data." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302553.
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This thesis covers the topic of depth- assisted Structure from Motion (SfM). When performing classic SfM, the goal is to reconstruct a 3D scene using only a set of unstructured RGB images. What is attempted to be achieved in this thesis is adding the depth dimension to the problem formulation, and consequently create a system that can receive a set of RGBD images. The problem has been addressed by modifying an already existing SfM pipeline and in particular, its Bundle Adjustment (BA) process. Comparisons between the modified framework and the baseline framework resulted in conclusions regarding the impact of the modifications. The results show mainly two things. First of all, the accuracy of the framework is increased in most situations. The difference is the most significant when the captured scene only is covered from a small sector. However, noisy data can cause the modified pipeline to decrease in performance. Secondly, the run time of the framework is significantly reduced. A discussion of how to modify other parts of the pipeline is covered in the conclusion of the report.Följande examensarbete behandlar ämnet djupassisterad Struktur genom Rörelse (eng. SfM). Vid klassisk SfM är målet att återskapa en 3D scen, endast med hjälp av en sekvens av oordnade RGB bilder. I djupassiterad SfM adderas djupinformationen till problemformulering och följaktligen har ett system som kan motta RGBD bilder skapats. Problemet har lösts genom att modifiera en befintlig SfM- mjukvara och mer specifikt dess Buntjustering (eng. BA). Resultatet från den modifierade mjukvaran jämförs med resultatet av originalutgåvan för att dra slutsatser rådande modifikationens påverkan på prestandan. Resultaten visar huvudsakligen två saker. Först och främst, den modifierade mjukvaran producerar resultat med högre noggrannhet i de allra flesta fall. Skillnaden är som allra störst när bilderna är tagna från endast en liten sektor som omringar scenen. Data med brus kan dock försämra systemets prestanda aningen jämfört med orginalsystemet. För det andra, så minskar exekutionstiden betydligt. Slutligen diskuteras hur mjukvaran kan vidareutvecklas för att ytterligare förbättra resultaten.
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Clift, Louis G. "Robotic 3D reconstruction utilising structure from motion." Thesis, University of Essex, 2017. http://repository.essex.ac.uk/20734/.
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Sensing the real-world is a well-established and continual problem in the field of robotics. Investigations into autonomous aerial and underwater vehicles have extended this challenge into sensing, mapping and localising in three dimensions. This thesis seeks to understand and tackle the challenges of recovering 3D information from an environment using vision alone. There is a well-established literature on the principles of doing this, and some impressive demonstrations; but this thesis explores the practicality of doing vision-based 3D reconstruction using multiple, mobile robotic platforms, the emphasis being on producing accurate 3D models. Typically, robotic platforms such as UAVs have a single on-board camera, restricting which method of visual 3D recovery can be employed. This thesis specifically explores Structure from Motion, a monocular 3D reconstruction technique which produces detailed and accurate, although slow to calculate, 3D reconstructions. It examines how well proof-of-concept demonstrations translate onto the kinds of robotic systems that are commonly deployed in the real world, where local processing is limited and network links have restricted capacity. In order to produce accurate 3D models, it is necessary to use high-resolution imagery, and the difficulties of working with this on remote robotic platforms is explored in some detail.
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Van, Wyk Barry-Michael Morné. "Verifying stereo vision using structure from motion /." Link to the online version, 2008. http://hdl.handle.net/10019/922.
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Huynh, L. (Lam). "Structure-from-motion using convolutional neural networks." Master's thesis, University of Oulu, 2018. http://jultika.oulu.fi/Record/nbnfioulu-201809062760.
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Abstract. There is an increasing interest in the research community to 3D scene reconstruction from monocular RGB cameras. Conventionally, structure from motion or special hardware such as depth sensors or LIDAR systems were used to reconstruct the point clouds of complex scenes. However, structure from motion technique usually fails to create the dense point cloud, while particular sensors are inconvenient and more expensive than RGB cameras. Recent advances in deep learning research have presented remarkable results in many computer vision tasks. Nevertheless, complete solution for large-scale dense 3D point cloud reconstruction still remains untouched.
This thesis introduces a deep-learning-based structure-from-motion pipeline for the dense 3D scene reconstruction problem. Several deep neural networks models were trained to predict the single view depth maps, and relative camera poses from RGB video frames. First, the obtained depth values were sequentially scaled to the first depth map. Next, the iterative closest point algorithm was utilized to further align the estimated camera poses. From these two processed cues, the point clouds of the scene were reconstructed by simple concatenation of 3D points.
Although the final point cloud results are encouraging and in certain aspects preferable to the conventional structure from motion method, the system is just tackling the 3D reconstruction problem to some extent. The prediction outputs still have errors, especially in the camera orientation estimation. This system can be seen as the initial study that opens up lots of research questions and improvements in the future. Besides, the study also signified the positive intimation for using unsupervised deep learning scheme to address the 3D scene reconstruction task.
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Aitken, Victor C. (Victor Charles) Carleton University Dissertation Engineering Electrical. "Motion and structure estimation in noisy monocular image sequences: specialization to planar motion." Ottawa, 1991.
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Merrell, Paul Clark. "Structure from Motion Using Optical Flow Probability Distributions." Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd764.pdf.
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McKinnon, David N. R. "Structure from motion from uncalibrated digital image sequences /." [St. Lucia, Qld.], 2002. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe17117.pdf.
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Eichner, Hubert. "Internal structure of the fly elementary motion detector." Diss., lmu, 2012. http://nbn-resolving.de/urn:nbn:de:bvb:19-140290.
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Hanmer, P. "Structure and motion of ions in polymer electrolytes." Thesis, University of Kent, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.259618.
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Jiang, Qing. "Fractal structure of aggregates induced by shear motion." Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186241.
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Aggregates formed by Brownian motion, shear motion, and differential sedimentation are found to be fractals. To characterize the structure and properties of these aggregates, a set of equations was derived to describe the relationship between aggregate size and solid volume, porosity, density, settling velocity and collision efficiency. By extending concepts developed by Friedlander and Hunt for the analysis of nonfractal particle coagulation at steady state, a steady-state size distribution model for fractal aggregates was developed for size intervals dominated by Brownian motion, shear, or differential sedimentation. A non-steady-state size distribution (two-slope) method was proposed for determining three dimensional fractal dimensions. Using size distributions in terms of both aggregate length and solid volume, a method was also developed to obtain the relationship between solid volume and aggregate size for examining the variation of fractal dimensions over a given size range. Coagulation experiments with latex microspheres in salt solutions were conducted to test predictions of the steady-state model and to study the effects of salt concentration and shear rates on the fractal structure of aggregates in both laminar shear and turbulent shear devices. The prediction of the steady-state model over the subrange dominated by shear motion was verified by the results of the experiments at 0.15 M NaCl and a shear rate of 3.4 s⁻¹, and the experiment at 0.6 M NaCl and a shear rate of 0.5 s⁻¹. In turbulent flow, fractal dimensions were not a function of salt concentration. In laminar shear, at NaCl concentration ≤ 0.3 M fractal dimensions were 1.9 to 2.1 with a collision efficiency of 10⁻³. High NaCl concentrations (0.45 to 0.6M) resulted in lower fractal dimensions of 1.4 to 1.7 with a collision efficiency of 10⁻¹. Laminar shear rates of 0.5 to 15 s⁻¹ had little effect on fractal dimensions. Boundary fractal dimensions of aggregates were not sensitive to changes in NaCl concentrations in both laminar and turbulent flow but they were a function of laminar shear rate.
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FUSIELLO, ANDREA. "THREE-DIMENSIONAL VISION FOR STRUCTURE AND MOTION ESTIMATION." Doctoral thesis, Università degli studi di Trieste, 1999. http://thesis2.sba.units.it/store/handle/item/12451.
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1997/1998Questa tesi, intitolata Visione Tridimensionale per la stima di Struttura e Moto, tratta di tecniche di Visione Artificiale per la stima delle proprietà geometriche del mondo tridimensionale a partire da immagini numeriche. Queste proprietà sono essenziali per il riconoscimento e la classificazione di oggetti, la navigazione di veicoli mobili autonomi, il reverse engineering e la sintesi di ambienti virtuali. In particolare, saranno descritti i moduli coinvolti nel calcolo della struttura della scena a partire dalle immagini, e verranno presentati contributi originali nei seguenti campi. Rettificazione di immagini steroscopiche. Viene presentato un nuovo algoritmo per la rettificazione, il quale trasforma una coppia di immagini stereoscopiche in maniera che punti corrispondenti giacciano su linee orizzontali con lo stesso indice. Prove sperimentali dimostrano il corretto comportamento del metodo, come pure la trascurabile perdita di accuratezza nella ricostruzione tridimensionale quando questa sia ottenuta direttamente dalle immagini rettificate. Calcolo delle corrispondenze in immagini stereoscopiche. Viene analizzato il problema della stereovisione e viene presentato un un nuovo ed efficiente algoritmo per l'identificazione di coppie di punti corrispondenti, capace di calcolare in modo robusto la disparità stereoscopica anche in presenza di occlusioni. L'algoritmo, chiamato SMW, usa uno schema multi-finestra adattativo assieme al controllo di coerenza destra-sinistra per calcolare la disparità e l'incertezza associata. Gli esperimenti condotti con immagini sintetiche e reali mostrano che SMW sortisce un miglioramento in accuratezza ed efficienza rispetto a metodi simili Inseguimento di punti salienti. L'inseguitore di punti salienti di Shi-Tomasi- Kanade viene migliorato introducendo uno schema automatico per lo scarto di punti spuri basato sulla diagnostica robusta dei campioni periferici ( outliers ). Gli esperimenti con immagini sintetiche e reali confermano il miglioramento rispetto al metodo originale, sia qualitativamente che quantitativamente. Ricostruzione non calibrata. Viene presentata una rassegna ragionata dei metodi per la ricostruzione di un modello tridimensionale della scena, a partire da una telecamera che si muove liberamente e di cui non sono noti i parametri interni. Il contributo consiste nel fornire una visione critica e unificata delle più recenti tecniche. Una tale rassegna non esiste ancora in letterarura. Moto tridimensionale. Viene proposto un algoritmo robusto per registrate e calcolare le corrispondenze in due insiemi di punti tridimensionali nei quali vi sia un numero significativo di elementi mancanti. Il metodo, chiamato RICP, sfrutta la stima robusta con la Minima Mediana dei Quadrati per eliminare l'effetto dei campioni periferici. Il confronto sperimentale con una tecnica simile, ICP, mostra la superiore robustezza e affidabilità di RICP.
This thesis addresses computer vision techniques estimating geometrie properties of the 3-D world /rom digital images. Such properties are essential for object recognition and classification, mobile robots navigation, reverse engineering and synthesis of virtual environments. In particular, this thesis describes the modules involved in the computation of the structure of a scene given some images, and offers original contributions in the following fields. Stereo pairs rectification. A novel rectification algorithm is presented, which transform a stereo pair in such a way that corresponding points in the two images lie on horizontal lines with the same index. Experimental tests prove the correct behavior of the method, as well as the negligible decrease oLthe accuracy of 3-D reconstruction if performed from the rectified images directly. Stereo matching. The problem of computational stereopsis is analyzed, and a new, efficient stereo matching algorithm addressing robust disparity estimation in the presence of occlusions is presented. The algorithm, called SMW, is an adaptive, multi-window scheme using left-right consistency to compute disparity and its associated uncertainty. Experiments with both synthetic and real stereo pairs show how SMW improves on closely related techniques for both accuracy and efficiency. Features tracking. The Shi-Tomasi-Kanade feature tracker is improved by introducing an automatic scheme for rejecting spurious features, based on robust outlier diagnostics. Experiments with real and synthetic images confirm the improvement over the original tracker, both qualitatively and quantitatively. 111 Uncalibrated vision. A review on techniques for computing a three-dimensional model of a scene from a single moving camera, with unconstrained motion and unknown parameters is presented. The contribution is to give a critical, unified view of some of the most promising techniques. Such review does not yet exist in the literature. 3-D motion. A robust algorithm for registering and finding correspondences in two sets of 3-D points with significant percentages of missing data is proposed. The method, called RICP, exploits LMedS robust estimation to withstand the effect of outliers. Experimental comparison with a closely related technique, ICP, shows RICP's superior robustness and reliability.
XI Ciclo
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Versione digitalizzata della tesi di dottorato cartacea.
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Stoyanov, Danail Valentinov. "Recovering 3D structure and motion in robotic laparoscopic surgery." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430137.
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Li, Jian. "Fusing motion information with spatial structure for surveillance applications." Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445811.
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Kavamoto, Fayad João Renato. "Local deformation modelling for non-rigid structure from motion." Thesis, Queen Mary, University of London, 2013. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8491.
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Reconstructing the 3D geometry of scenes based on monocular image sequences is a long-standing problem in computer vision. Structure from motion (SfM) aims at a data-driven approach without requiring a priori models of the scene. When the scene is rigid, SfM is a well understood problem with solutions widely used in industry. However, if the scene is non-rigid, monocular reconstruction without additional information is an ill-posed problem and no satisfactory solution has yet been found. Current non-rigid SfM (NRSfM) methods typically aim at modelling deformable motion globally. Additionally, most of these methods focus on cases where deformable motion is seen as small variations from a mean shape. In turn, these methods fail at reconstructing highly deformable objects such as a flag waving in the wind. Additionally, reconstructions typically consist of low detail, sparse point-cloud representation of objects. In this thesis we aim at reconstructing highly deformable surfaces by modelling them locally. In line with a recent trend in NRSfM, we propose a piecewise approach which reconstructs local overlapping regions independently. These reconstructions are merged into a global object by imposing 3D consistency of the overlapping regions. We propose our own local model – the Quadratic Deformation model – and show how patch division and reconstruction can be formulated in a principled approach by alternating at minimizing a single geometric cost – the image re-projection error of the reconstruction. Moreover, we extend our approach to dense NRSfM, where reconstructions are preformed at the pixel level, improving the detail of state of the art reconstructions. Finally we show how our principled approach can be used to perform simultaneous segmentation and reconstruction of articulated motion, recovering meaningful segments which provide a coarse 3D skeleton of the object.
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Venter, Chris (Christian Johannes). "Structure from motion estimation using a nonlinear Kalman filter." Thesis, Stellenbosch : Stellenbosch University, 2002. http://hdl.handle.net/10019.1/53071.
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Thesis (MScEng)--University of Stellenbosch, 2002.ENGLISH ABSTRACT: Structure from Motion is defined as the problem of extracting the 3d motion of a camera moving through a scene, as well as the 3d structure of the scene, from the image sequence produced by the camera over time. Several methods based on the Kalman filter have been proposed in the past, mostly based on the Extended Kalman filter. We propose an algorithm based on the dual Unscented Kalman filter to estimate the structure and motion of an object under perspective projection. It is shown that the algorithm is stable and accurate under synthetic as well as real-world conditions.
AFRIKAANSE OPSOMMING: Struktuur vanuit Beweging is 'n rekenaar-visie probleem waarin die 3d beweging van 'n kamera deur 'n ruimte, asook die 3d struktuur van die ruimte, bepaal moet word slegs vanuit die 2d beelde in die beeldreeks wat deur die kamera geneem word. 'n Verskeie reeks oplossings, gebaseer op die Kalman filter, is reeds voorgestelom die probleem op te los. Meeste van die oplossings implementeer die "Extended Kalman filter", of EKF. Ons stel 'n algoritme voor, gebaseer op 'n nuwe nie-lineêre benadering tot die Kalman filter, die sogenaamde "Unscented Kalman filter", of UKF. Hierdie algoritme bepaal die struktuur en beweging onder 'n perspektief-projeksie kamera. Daar word getoon dat die algoritme stabiel en akkuraat funskioneer onder sintetiese sowel as reële toevoer.
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Rabaud, Vincent C. "Manifold learning techniques for non-rigid structure from motion." Diss., [La Jolla, Calif.] : University of California, San Diego, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3344538.
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Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed March 13, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 96-100).
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Dietrich, James. "Applications of Structure-from-Motion Photogrammetry to Fluvial Geomorphology." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/18701.
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Since 2011, Structure-from-Motion Multi-View Stereo Photogrammetry (SfM or SfM-MVS) has gone from an overlooked computer vision technique to an emerging methodology for collecting low-cost, high spatial resolution three-dimensional data for topographic or surface modeling in many academic fields. This dissertation examines the applications of SfM to the field of fluvial geomorphology. My research objectives for this dissertation were to determine the error and uncertainty that are inherent in SfM datasets, the use of SfM to map and monitor geomorphic change in a small river restoration project, and the use of SfM to map and extract data to examine multi-scale geomorphic patterns for 32 kilometers of the Middle Fork John Day River. SfM provides extremely consistent results, although there are systematic errors that result from certain survey patterns that need to be accounted for in future applications. Monitoring change on small restoration stream channels with SfM gave a more complete spatial perspective than traditional cross sections on small-scale geomorphic change. Helicopter-based SfM was an excellent platform for low-cost, large scale fluvial remote sensing, and the data extracted from the imagery provided multi-scalar perspectives of downstream patterns of channel morphology. This dissertation makes many recommendations for better and more efficient SfM surveys at all of the spatial scales surveyed. By implementing the improvements laid out here and by other authors, SfM will be a powerful tool that will make 3D data collection more accessible to the wider geomorphic community.
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Li, Yanhua. "Efficient recursive factorization methods for determining structure from motion." Title page, abstract and contents only, 2000. http://web4.library.adelaide.edu.au/theses/09PH/09phl6929.pdf.
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Mehdi, Wasan. "Structure evaluation of computer human animation quality." Thesis, University of Bedfordshire, 2013. http://hdl.handle.net/10547/322822.
Full textAbstract:
This work will give a wide survey for various techniques that are present in the field of character computer animation, which concentrates particularly on those techniques and problems involved in the production of realistic character synthesis and motion. A preliminary user study (including Questionnaire, online publishing such as flicker.com, interview, multiple choice questions, publishing on Android mobile phone, and questionnaire analysis, validation, statistical evaluation, design steps and Character Animation Observation) was conducted to explore design questions, identify users' needs, and obtain a "true story" of quality character animation and the effect of using animation as useful tools in Education. The first set of questionnaires were designed to accommodate the evaluation of animation from candidates from different walks of life, ranging from animators, gamers, teacher assistances (TA), students, teaches, professionals and researchers using and evaluating pre-prepared animated character videos scenarios, and the study outcomes has reviewed the recent advances techniques of character animation, motion editing that enable the control of complex animations by interactively blending, improving and tuning artificial or captured motions. The goal of this work was to augment the students learning intuition by providing ways to make education and learning more interesting, useful and fun objectively, in order to improve students’ respond and understanding to any subject area through the use of animation also by producing the required high quality motion, reaction, interaction and story board to viewers of the motion. We present a variety of different evaluation to the motion quality by measuring user sensitivity, observations to any noticeable artefact, usability, usefulness etc. to derive clear useful guidelines from the results, and discuss several interesting systematic trends we have uncovered in the experimental data. We also present an efficient technique for evaluating the capability of animation influence on education to fulfil the requirements of a given scenario, along with the advantages and the effect on those deficiencies of some methods commonly used to improve animation quality to serve the learning process. Finally, we propose a wide range of extensions and statistical calculation enabled by these evaluation tools, such as Wilcoxon, F-test, T-test, Wondershare Quiz creator (WQC), Chi square and many others explained with full details.
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Wu, Xiong-Jian. "Motion and wave load analyses of large offshore structures and special vessels in waves." Thesis, Brunel University, 1990. http://bura.brunel.ac.uk/handle/2438/7865.
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Predictions of the environmental loading and induced motional and structural responses are among the most important aspects in the overall design process of offshore structures and ships. In this thesis, attention is focused on the wave loads and excited bodily motion responses of large offshore structures and special vessels. With the aim of improving the existing theoretical methods to provide techniques of theoretical effectiveness, computational efficiency, and engineering practicality in marine and offshore applications, the thesis concentrates upon describing fundamental and essential aspects in the physical phenomenon associated with wave-structure interactions and deriving new methods and techniques to analyse offshore structures and unconventional ships of practical interest. The total wave force arising from such a wave-structural interaction is assumed to be a simple superposition of the potential and the viscous flow force components. The linear potential forces are solved by the Green function integral equation whilst the viscous forces are estimated based on the Morison's damping formula. Forms of the Green function integral equation and the associated Green function are given systematically for various practical cases. The relevant two-dimensional versions are then derived by a transformation procedure. Techniques are developed to solve the integral equation numerically including the interior integral formulation and, in particular, to tackle the mathematical difficulties at irregular frequencies. In applying the integral equations to solve problems with various offshore structures and special vessels, some modified, improved or simplified methods are proposed. At first, simplified method is derived for predictions of the surge, sway and yaw motions of elongated bodies of full sectional geometry or structures with shallow draft. Then, a new shallow draft theory is described for both three- and two-dimensional cases with inclusion of the finite draft effect. Furthermore, a three-dimensional strip method is formulated where the end effects of the body are fully taken into account. Finally, an approximation to the horizontal mean drift forces of multi-column offshore structures are presented. Some new findings are also discussed including the multiple resonances occurring in the motions of multi-hulled marine structures due to the wave-body interaction, the mutual cancellation effect of the diffraction and the radiation forces arising from a full shaped slender body, and so on. Further to those verification studies for individual methods developed, more comprehensive example investigations are given related to two industrial applications. One is a derrick barge semi-submersible with zero forward speed; and the other, a SWATH ship with considerable speed. By correlation of all the proposed approaches with available analytical, numerical and experimental data, the thesis tries to demonstrate a principle that as long as principal physical aspects in the wave-structure interaction problem are properly treated, an appropriately modified or simplified method works, performs well and, sometimes, even better.
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Silva, Bruno Marques Ferreira da. "Odometria visual baseada em t?cnicas de structure from motion." Universidade Federal do Rio Grande do Norte, 2011. http://repositorio.ufrn.br:8080/jspui/handle/123456789/15364.
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Made available in DSpace on 2014-12-17T14:55:51Z (GMT). No. of bitstreams: 1
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Previous issue date: 2011-02-15Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Visual Odometry is the process that estimates camera position and orientation based solely on images and in features (projections of visual landmarks present in the scene) extraced from them. With the increasing advance of Computer Vision algorithms and computer processing power, the subarea known as Structure from Motion (SFM) started to supply mathematical tools composing localization systems for robotics and Augmented Reality applications, in contrast with its initial purpose of being used in inherently offline solutions aiming 3D reconstruction and image based modelling. In that way, this work proposes a pipeline to obtain relative position featuring a previously calibrated camera as positional sensor and based entirely on models and algorithms from SFM. Techniques usually applied in camera localization systems such as Kalman filters and particle filters are not used, making unnecessary additional information like probabilistic models for camera state transition. Experiments assessing both 3D reconstruction quality and camera position estimated by the system were performed, in which image sequences captured in reallistic scenarios were processed and compared to localization data gathered from a mobile robotic platform
Odometria Visual ? o processo pelo qual consegue-se obter a posi??o e orienta??o de uma c?mera, baseado somente em imagens e consequentemente, em caracter?sticas (proje??es de marcos visuais da cena) nelas contidas. Com o avan?o nos algoritmos e no poder de processamento dos computadores, a sub?rea de Vis?o Computacional denominada de Structure from Motion (SFM) passou a fornecer ferramentas que comp?em sistemas de localiza??o visando aplica??es como rob?tica e Realidade Aumentada, em contraste com o seu prop?sito inicial de ser usada em aplica??es predominantemente offline como reconstru??o 3D e modelagem baseada em imagens. Sendo assim, este trabalho prop?e um pipeline de obten??o de posi??o relativa que tem como caracter?sticas fazer uso de uma ?nica c?mera calibrada como sensor posicional e ser baseado interamente nos modelos e algoritmos de SFM. T?cnicas usualmente presentes em sistemas de localiza??o de c?mera como filtros de Kalman e filtros de part?culas n?o s?o empregadas, dispensando que informa??es adicionais como um modelo probabil?stico de transi??o de estados para a c?mera sejam necess?rias. Experimentos foram realizados com o prop?sito de avaliar tanto a reconstru??o 3D quanto a posi??o de c?mera retornada pelo sistema, atrav?s de sequ?ncias de imagens capturadas em ambientes reais de opera??o e compara??es com um ground truth fornecido pelos dados do od?metro de uma plataforma rob?tica
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Julià, Ferré Ma Carme. "Missing Data Matrix Factorization Addressing the Structure from Motion Problem." Doctoral thesis, Universitat Autònoma de Barcelona, 2008. http://hdl.handle.net/10803/5785.
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Aquest treball es centra en la factorització de matrius per obtenir l'Estructura a partir del Moviment (SFM). La idea és descomposar la matriu de trajectòries en la matriu de moviment, que conté la posició relativa càmera-objecte a cada frame, i la matriu de forma, que conté les coordenades 3D dels punts característics. Aquesta factorització es pot obtenir utilitzant que la matriu de trajectòries té un rang reduït. En particular, si les trajectòries pertanyen a un únic objecte rígid, la matriu té com a molt rang 4. Tot i que s'han proposat diverses tècniques per tractar el problema de les matrius amb forats, aquestes poden no donar resultats correctes quan el percentatge de forats a la matriu és molt gran. Proposem un esquema multiresolució iteratiu per poder tractar aquests casos amb molts elements buits a la matriu de trajectòries. L'esquema proposat consisteix en considerar submatrius amb un percentatge de forats reduït. Seguidament, els forats d'aquestes matrius són emplenats aplicant un mètode de factorització. L'objectiu final és obtenir millors resultats aplicant un mètode de factorització a la matriu emplenada amb l'esquema proposat, enlloc d'aplicar-lo a la matriu inicial, que presenta un elevat percentatge de forats. En el cas de matrius de trajectòries corresponents a punts característics que pertanyen a diversos objectes, les tècniques de factorització no es poden aplicar directament per
obtenir el moviment i la forma de cada objecte, ja que les trajectòries no estan ordenades per objectes. A més a més, s'ha de tenir en compte un altre problema: l'estimació del rang de la matriu de trajectòries. El problema és que amb forats, el rang de la matriu no pot ser calculat directament. Per altra banda, com que hi ha múltiples objectes, és difícil d'estimar-lo, sense utilitzar informació com ara nombre d'objectes o tipus de moviment d'aquests. Presentem una tècnica per estimar el rang d'una matriu de trajectòries amb forats. La idea és que, si les trajectòries pertanyen a objectes rígids, la freqüència espectral de la matriu de trajectòries inicial no hauria de variar un cop la matriu ha estat emplenada. Els forats de la matriu són emplenats amb un mètode de factorització, considerant diferents valors per al rang de la matriu. Al mateix temps, el rang de la matriu de trajectòries és estimat fent servir una mesura que compara la freqüència espectral de cada matriu emplenada amb la de la matriu inicial. El proper pas consisteix en segmentar les trajectòries segons el seu moviment. Finalment, qualsevol tècnica d'Estructura a partir de Moviment per a un únic objecte pot ser aplicada per trobar el moviment i la forma de cada objecte.
Intentem aplicar la metodologia proposada per al problema de l'Estructura a partir de Moviment a d'altres aplicacions, no només dins el camp de la visió per computador. En particular, l'objectiu és adaptar els mètodes Alternats per poder aplicar-los a diferents problemes de dimensionalitat reduïda. Una de les possibles aplicacions és la fotometria: la idea és recuperar la reflectància i les normals a la superfície i la direcció de la llum en cada imatge, a partir d'imatges obtingudes sota diferents condicions de llum. En una segona aplicació, l'objectiu és adaptar els mètodes Alternats per poder omplir els forats en una matriu de dades provinents d'expressions de gens. Aquestes matrius són generades amb la informació que proporcionen els DNA microarrays. Finalment, els mètodes Alternats són aplicats a matrius de dades de sistemes de recomanació, molt usats en E-commerce. Aquestes matrius contenen puntuacions que els usuaris han donat a certs productes. La idea és predir les puntuacions que un usuari concret donaria a altres productes, utilitzant la informació emmagatzemada en el sistema.
This work is focused on the missing data matrix factorization addressing the Structure from Motion (SFM) problem. The aim is to decompose a matrix of feature point trajectories into the motion and shape matrices, which contain the relative camera-object motion and the 3D positions of tracked feature points, respectively. This decomposition can be found by using the fact that the matrix of trajectories has a reduced rank. Although several techniques have been proposed to tackle this problem, they may give undesirable results when the percentage of missing data is high. An iterative multiresolution scheme is presented to deal with matrices with high percentages of missing data. Experimental results show the viability of the proposed approach.
In the multiple objects case, factorization techniques can not be directly applied to obtain the SFM of every object, since trajectories are not sorted into different objects. Furthermore, another problem should be faced out: the estimation of the rank of the matrix of trajectories. The problem is that, in this case, the rank of the matrix of trajectories is not bounded, since any prior knowledge about the number of objects nor about their motion is used. This problem becomes more difficult with missing data, since singular values can not be computed to estimate the rank. A technique to estimate the rank of a missing data matrix of trajectories is presented. The good performance of the proposed technique is empirically shown considering sequences with both, synthetic and real data. Once the rank is estimated and the matrix of trajectories is full, the motion segmentation of trajectories is computed. Finally, any factorization technique for the single object case gives the shape and motion of every object.
In addition to the SFM problem, this thesis also shows other applications that can be addressed by means of factorization techniques. Concretely, the Alternation technique, which is used through the thesis, is adapted to address each particular problem. The first proposed application is the photometric stereo: the goal is to recover the reflectance and surface normals and the light source direction at each frame, from a set of images taken under different lighting conditions. In a second application, the aim is to fill in missing data in gene expression matrices by using the Alternation technique. Finally, the Alternation technique is adapted to be applied in recommender systems, widely considered in E-commerce. For each application, experimental results are given in order to show the good performance of the proposed Alternation-based strategy.
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Baker, Patrick Terry. "Structure from motion on textures theory and application to calibration /." College Park, Md. : University of Maryland, 2005. http://hdl.handle.net/1903/2371.
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Thesis (PhD) -- University of Maryland, College Park, 2005.Thesis research directed by: Computer Science. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Bastanlar, Yalin. "Structure-from-motion For Systems With Perspective And Omnidirectional Cameras." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610833/index.pdf.
Full textAbstract:
In this thesis, a pipeline for structure-from-motion with mixed camera types is described and methods for the steps of this pipeline to make it effective and automatic are proposed. These steps can be summarized as calibration, feature point matching, epipolar geometry and pose estimation, triangulation and bundle adjustment. We worked with catadioptric omnidirectional and perspective cameras and employed the sphere camera model, which encompasses single-viewpoint catadioptric systems as well as perspective cameras.
For calibration of the sphere camera model, a new technique that has the advantage of linear and automatic parameter initialization is proposed. The projection of 3D points on a catadioptric image is represented linearly with a 6x10
projection matrix using lifted coordinates. This projection matrix is computed with an adequate number of 3D-2D correspondences and decomposed to obtain intrinsic and extrinsic parameters. Then, a non-linear optimization is performed to refine the parameters.
For feature point matching between hybrid camera images, scale invariant feature transform (SIFT) is employed and a method is proposed to improve the SIFT matching output. With the proposed approach, omnidirectional-perspective matching performance significantly increases to enable automatic point matching. In addition, the use of virtual camera plane (VCP) images is evaluated, which are perspective images produced by unwarping the corresponding region in the omnidirectional image.
The hybrid epipolar geometry is estimated using random sample consensus (RANSAC) and alternatives of pose estimation methods are evaluated. A weighting strategy for iterative linear triangulation which improves the structure estimation accuracy is proposed. Finally, multi-view structure-from-motion (SfM) is performed by employing the approach of adding views to the structure one by one. To refine the structure estimated with multiple views, sparse bundle adjustment method is employed with a modification to use the sphere camera model.
Experiments on simulated and real images for the proposed approaches are conducted. Also, the results of hybrid multi-view SfM with real images are demonstrated, emphasizing the cases where it is advantageous to use omnidirectional
cameras with perspective cameras.
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Ortiz, Steven Rey. "Structure from motion using omni-directional vision and certainty grids." Texas A&M University, 2004. http://hdl.handle.net/1969.1/1217.
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This thesis describes a method to create local maps from an omni-directional vision
system (ODVS) mounted on a mobile robot. Range finding is performed by a
structure-from-motion method, which recovers the three-dimensional position of objects
in the environment from omni-directional images. This leads to map-making,
which is accomplished using certainty grids to fuse information from multiple readings
into a two-dimensional world model. The system is demonstrated both on noise-free
data from a custom-built simulator and on real data from an omni-directional vision
system on-board a mobile robot. Finally, to account for the particular error characteristics
of a real omni-directional vision sensor, a new sensor model for the certainty
grid framework is also created and compared to the traditional sonar sensor model.
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D, M. BAPPY, and MD HAMIDUR RAHMAN. "A Study in 3D Structure Detection Implementing Forward Camera Motion." Thesis, Blekinge Tekniska Högskola, Sektionen för ingenjörsvetenskap, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-2002.
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In this thesis we have studied detection of 3D structures having a forward camera movement which has strong influence of translation along the optical axis of the camera. During the forward movement the camera might undergoes rotation and translation .We have used “Plane plus Parallax” algorithm to cancel out this unwanted rotation. The input to the algorithm is a sequence of frames aligned with respect to a certain planar surface. The algorithm gives three types of outputs. (i) Dense correspondence across all frames. (ii) Dense 3D structure relative to the planar surface. (ii) Focus of Expansion (FOE) in all frames with respect to reference frame. Camera calibration is not needed for this algorithm. We have applied this algorithm to real world images and synthetic images. In both cases the 3D structure information could be obtained clearly even for objects far from the reference plane. Our result shows the potential of the method in 3D reconstruction implementing ego-motion of a single camera.dm_aiub@yahoo.com 008801681006314
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Hengel, Anton van den. "Robust estimation of structure from motion in the uncalibrated case." Title page, abstract table of contents only, 2000. http://thesis.library.adelaide.edu.au/adt-SUA/public/adt-SUA20010719.141806.
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Bibliography: leaves 128-140. Electronic publication; Full text available in PDF format; abstract in HTML format. This thesis explores the application of numerical and statistical techniques for estimation of structure from motion in the uncalibrated case. It presents and compares a variety of methods for estimating the coefficients of the differential epipolar equation. The goal of this process is to derive a tractable total least squares estimator of structure from motion robust to the presence of inaccuracies in the data. Methods are also presented for rectifying optical flow to a particular motion estimate, eliminating outliers from the data, and calculating the relative motion of a camera over an image sequence. (abstract) Electronic reproduction.[Australia] :Australian Digital Theses Program,2001.
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Fathi, Habib. "Videogrammetric roof surveying using a hybrid structure from motion approach." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52972.
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In a roofing project, acquiring the underlying as-built 3D geometry and visualizing the roof structure is needed in different phases of the project life-cycle. Architectural drawings, building information model (BIM) files, or aerial photogrammetry are used to estimate the roofing area in the bidding process. However, as a roof structure is never built to the exact drawing dimensions, as-built dimensions of boundaries of every roof plane have to be obtained several times during the course of its build. There are a number of surveying methods that can be used for this purpose: tape measuring, total station surveying, aerial photogrammetry, and laser scanning. However, obtaining measurements using these methods could be costly in terms of equipment, labor, and/or worker exposure to safety hazards. Aiming to address this limitation and provide roofing practitioners with an alternative roof surveying and visualization method that is simple to use, automated, inexpensive, and safe, a close-range videogrammetric roof 3D reconstruction framework is presented in this research. When using this method, a roofing contractor will simply collect stereo video streams of a target roof. The captured data is processed to generate a 3D wire-diagram for every roof plane. In this process, distinctive visual features of the scene (e.g., 2D points and lines) are first automatically detected and matched between video frames. Matched features and the camera calibration information are used to compute an initial estimation of the 3D structure. Then, a hybrid bundle adjustment algorithm is used to refine the result and acquire the geometry that has the maximum likelihood. Afterwards, different roof planes are found and a measurable 3D wire-diagram is generated for each plane.
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Stein, Gideon P. (Gideon Pascal). "Geometric and photometric constraints : motion and structure from three views." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9959.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 165-171).
by Gideon P. Stein.
Ph.D.
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Pizarro, Oscar. "Large scale structure from motion for autonomous underwater vehicle surveys." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/39185.
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Thesis (Ph. D.)--Joint Program in Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Ocean Engineering; and the Woods Hole Oceanographic Institution), 2004.Includes bibliographical references (p. 177-190).
Our ability to image extended underwater scenes is severely limited by attenuation and backscatter. Generating a composite view from multiple overlapping images is usually the most practical and flexible way around this limitation. In this thesis we look at the general constraints associated with imaging from underwater vehicles for scientific applications - low overlap, non-uniform lighting and unstructured motion - and present a methodology for dealing with these constraints toward a solution of the problem of large area 3D reconstruction. Our approach assumes navigation data is available to constrain the structure from motion problem. We take a hierarchical approach where the temporal image sequence is broken into subsequences that are processed into 3D reconstructions independently. These submaps are then registered to infer their overall layout in a global frame. From this point a bundle adjustment refines camera and structure estimates. We demonstrate the utility of our techniques using real data obtained during a SeaBED AUV coral reef survey. Test tank results with ground truth are also presented to validate the methodology.
by Oscar Pizarro.
Ph.D.
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Miller, Jordan Mitchell. "Estimation of individual tree metrics using structure-from-motion photogrammetry." Thesis, University of Canterbury. Geography, 2015. http://hdl.handle.net/10092/11035.
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The deficiencies of traditional dendrometry mean improvements in methods of tree mensuration are necessary in order to obtain accurate tree metrics for applications such as resource appraisal, and biophysical and ecological modelling. This thesis tests the potential of SfM-MVS (Structure-fromMotion with Multi-View Stereo-photogrammetry) using the software package PhotoScan Professional, for accurately determining linear (2D) and volumetric (3D) tree metrics. SfM is a remote sensing technique, in which the 3D position of objects is calculated from a series of photographs, resulting in a 3D point cloud model. Unlike other photogrammetric techniques, SfM requires no control points or camera calibration. The MVS component of model reconstruction generates a mesh surface based on the structure of the SfM point cloud.
The study was divided into two research components, for which two different groups of study trees were used: 1) 30 small, potted ‘nursery’ trees (mean height 2.98 m), for which exact measurements could be made and field settings could be modified, and; 2) 35 mature ‘landscape’ trees (mean height 8.6 m) located in parks and reserves in urban areas around the South Island, New Zealand, for which field settings could not be modified.
The first component of research tested the ability of SfM-MVS to reconstruct spatially-accurate 3D models from which 2D (height, crown spread, crown depth, stem diameter) and 3D (volume) tree metrics could be estimated. Each of the 30 nursery trees was photographed and measured with traditional dendrometry to obtain ground truth values with which to evaluate against SfM-MVS estimates. The trees were destructively sampled by way of xylometry, in order to obtain true volume values. The RMSE for SfM-MVS estimates of linear tree metrics ranged between 2.6% and 20.7%, and between 12.3% and 47.5% for volumetric tree metrics. Tree stems were reconstructed very well though slender stems and branches were reconstructed poorly.
The second component of research tested the ability of SfM-MVS to reconstruct spatially-accurate 3D models from which height and DBH could be estimated. Each of the 35 landscape trees, which varied in height and species, were photographed, and ground truth values were obtained to evaluate against SfM-MVS estimates. As well as this, each photoset was thinned to find the minimum number of images required to achieve total image alignment in PhotoScan and produce an SfM point cloud (minimum photoset), from which 2D metrics could be estimated. The height and DBH were estimated by SfM-MVS from the complete photosets with RMSE of 6.2% and 5.6% respectively. The height and DBH were estimated from the minimum photosets with RMSE of 9.3% and 7.4% respectively. The minimum number of images required to achieve total alignment was between 20 and 50. There does not appear to be a correlation between the minimum number of images required for alignment and the error in the estimates of height or DBH (R2 =0.001 and 0.09 respectively). Tree height does not appear to affect the minimum number of images required for image alignment (R 2 =0.08).
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Bedell, Emily Jane. "Unmanned Aerial Vehicle Based Structure from Motion Biomass Inventory Estimates." Thesis, Portland State University, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10244001.
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Riparian vegetation restoration efforts demand cost effective, accurate, and replicable impact assessments. In this thesis a method is presented using an Unmanned Aerial Vehicle (UAV) equipped with a GoPro digital camera to collect photogrammetric data of a 2.02-acre riparian restoration. A three-dimensional point cloud was created from the photos using Structure from Motion (SfM) techniques. The point cloud was analyzed and compared to traditional, ground-based monitoring techniques. Ground truth data collected using the status-quo approach was collected on 6.3% of the study site and averaged across the entire site to report stem heights in stems/acre in three height classes, 0-3 feet, 3-7 feet, and greater than 7 feet. The project site was divided into four analysis sections, one for derivation of parameters used in the UAV data analysis, and the remaining three sections reserved for method validation. The most conservative of several methods tested comparing the ground truth data to the UAV generated data produced an overall error of 21.6% and indicated an r2 value of 0.98. A Bland Altman analysis indicated a 99% probability that the UAV stems/plot result will be within 159 stems/plot of the ground truth data. The ground truth data is reported with an 80% confidence interval of +/- 844 stems/plot, thus the UAV was able to estimate stems well within this confidence interval. Further research is required to validate this method longitudinally at this same site and across varying ecologies. These results suggest that UAV derived environmental impact assessments at riparian restoration sites may offer competitive performance and value.
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Chakraborty, Manali. "Real-time image-based motion detection using color and structure." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.
Full text
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Bedell, Emily Jane. "Unmanned Aerial Vehicle Based Structure from Motion Biomass Inventory Estimates." PDXScholar, 2016. https://pdxscholar.library.pdx.edu/open_access_etds/3368.
Full textAbstract:
Riparian vegetation restoration efforts demand cost effective, accurate, and replicable impact assessments. In this thesis a method is presented using an Unmanned Aerial Vehicle (UAV) equipped with a GoPro digital camera to collect photogrammetric data of a 2.02-acre riparian restoration. A three-dimensional point cloud was created from the photos using Structure from Motion (SfM) techniques. The point cloud was analyzed and compared to traditional, ground-based monitoring techniques. Ground truth data collected using the status-quo approach was collected on 6.3% of the study site and averaged across the entire site to report stem heights in stems/acre in three height classes, 0-3 feet, 3-7 feet, and greater than 7 feet. The project site was divided into four analysis sections, one for derivation of parameters used in the UAV data analysis, and the remaining three sections reserved for method validation. The most conservative of several methods tested comparing the ground truth data to the UAV generated data produced an overall error of 21.6% and indicated an r2 value of 0.98. A Bland Altman analysis indicated a 99% probability that the UAV stems/plot result will be within 159 stems/plot of the ground truth data. The ground truth data is reported with an 80% confidence interval of +/- 844 stems/plot, thus the UAV was able to estimate stems well within this confidence interval. Further research is required to validate this method longitudinally at this same site and across varying ecologies. These results suggest that UAV derived environmental impact assessments at riparian restoration sites may offer competitive performance and value.
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Linn, Anthony B. "A computational study of turbulent structure formation." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-042607-093941/.
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Armistead, Corrine Chapman. "Applications of 'Structure from Motion' Photogrammetry to River Channel Change Studies." Thesis, Boston College, 2013. http://hdl.handle.net/2345/3086.
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Thesis advisor: Noah SnyderThis study considers the feasibility and accuracy of using the Structure from Motion (SfM) technique to quantify changes in stream channel morphology. The SfM method utilizes common points across multiple photographs to create a three-dimensional representation of a study area. This model can then be georeferenced using ground control points. The camera locations and optics do not need to be known in this technique, making it simpler to implement in the field than traditional photogrammetry or ground-based lidar methods. Preliminary testing of this method was conducted in and around the Boston College campus during summer 2012 to determine the most appropriate tools and data collection plan for further fieldwork. I then applied the SfM method to a field site on the Souhegan River in southern New Hampshire, where I photographed two cross sections (one boulder-bedded, one sand-bedded) using a camera mounted on a 4.8 m pole. On the same day, I surveyed both cross sections using a total station with mm-scale accuracy. Inputting the photographs into the Agisoft PhotoScan software used for SfM reconstruction yielded several noteworthy results. First, when certain conditions are met, the model generated through SfM, built from a complex, high density (for example ~2,900 points per m2) point cloud, can then be used to deduce elevation data. Based on a point-by-point comparison, the SfM cross section averaged 3.6 cm (±3.4 cm standard deviation) higher than the total station survey. In other portions of the study site imaged for SfM reconstruction, a variety of difficulties prevented the development of a georeferenced three-dimensional model. These limitations, including shadowing, vegetation, camera vantage point, and location of ground control points, can be minimized in future studies to allow for better use of the SfM technique. As results of this study demonstrate, SfM reconstruction has the potential to generate accurate topographic data, which will be a powerful tool for future geomorphic studies, particularly for sites with relatively sparse vegetation and limited water
Thesis (BS) — Boston College, 2013
Submitted to: Boston College. College of Arts and Sciences
Discipline: Geology & Geophysics Honors Program
Discipline: Department of Earth and Environmental Sciences
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Yeh, Tien-Chiang. "Effects of Taiwan orography on the motion and structure of typhoons." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School; Available from the National Technical Information Service, 1992. http://handle.dtic.mil/100.2/ADA261819.
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Dissertation (Ph.D. in Meteorology) Naval Postgraduate School, December 1992.Dissertation supervisor(s): Chih-Pei Chang, Russell L. Elsberry. "December 1992." Bibliography: p. 279-282. Also available online.
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Guan, Hao. "Local features, structure-from-motion and view synthesis in spherical video." Thesis, University of York, 2016. http://etheses.whiterose.ac.uk/17414/.
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This thesis addresses the problem of synthesising new views from spherical video or image sequences. We propose an interest point detector and feature descriptor that allows us to robustly match local features between pairs of spherical images and use this as part of a structure-from-motion pipeline that allows us to estimate camera pose from a spherical video sequence. With pose estimates to hand, we propose methods for view stabilisation and novel viewpoint synthesis. In Chapter 3 we describe our contribution in the area of feature detection and description in spherical images. First, we present a novel representation for spherical images which uses a discrete geodesic grid composed of hexagonal pixels. Second, we extend the BRISK binary descriptor to the sphere, proposing methods for multiscale corner detection, sub-pixel position and sub-octave scale refinement and descriptor construction in the tangent space to the sphere. In Chapter 4 we describe our contributions in the area of spherical structure-from-motion. We revisit problems from multiview geometry in the context of spherical images. We propose methods suited to spherical camera geometry for the spherical-n-point problem and calibrated spherical reconstruction. We introduce a new probabilistic interpretation of spherical structure-from-motion which uses the von Mises-Fisher distribution in spherical feature point positions. This model provides an alternate objective function that we use in bundle adjustment. In Chapter 5 we describe our contributions in the area of view synthesis from spherical images. We exploit the camera pose estimates made by our pipeline and use these in two view synthesis applications. The first is view stabilisation where we remove the effect of viewing direction changes, often present in first person video. Second, we propose a method for synthesising novel viewpoints.
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Ly, Dieu Sang. "Structure from motion with hybrid cameras using point and line features." Amiens, 2011. http://www.theses.fr/2011AMIE0111.
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L’estimation de mouvement de caméras et la reconstruction de structure 3D (Structure from Motion ou SfM) ont déjà beaucoup étudiées. Il existe de nombreuses méthodes de SfM qui diffèrent en fonction du type de capteurs et de primitives utilisés. La plupart de ces approches ont été développées pour la vision perspective ou omnidirectionnelle mais très peu pour les deux. Une combinaison de la bonne résolution fournie par les caméras perspectives et le large champ de vue des caméras omnidirectionnelles devient très utile dans plusieurs applications comme la surveillance, la reconstruction de scène, la navigation d’un robot mobile, etc. C’est la raison pour laquelle nous recherchons une méthode qui est applicable à ces deux systèmes de vision. Nous proposons une technique de SfM basée droites qui possèdent de nombreuses caractéristiques avantageuses, particulièrement en milieu urbain. Cette méthode se compose de l’estimation de mouvement en deux étapes (calcul des rotations à partir de points de fuite de droites parallèles dans la scène et calcul des translations à partir de ces mêmes droites), la reconstruction de structure 3D et l’ajustement de faisceaux afin de raffiner les paramètres de caméras et de structure 3D. De plus, les points peuvent être intégrés dans l’estimation de translations pour améliorer le résultat. Ainsi, nous avons développé dans cette thèse une approche originale qui permet d’estimer le mouvement et de reconstruire la scène avec tout type de caméras centrales ou fish-eye et en utilisant deux types de primitives (les droites et les points)Structure from motion is a widely studied problem in computer vision. It refers to the estimation of camera motion and three-dimensional structure of the scene. There exist numerous solutions to structure from motion problems, varying in types of vision equipment, kinds of image feature and estimation process. Most of them coped with perspective or omnidirectional vision but very few with both. Combining the good resolution provided by perspective cameras and the wide field of view of omnidirectional ones has become an attractive trend. For this reason, we seek for an approach that is applicable to both of these vision sensors. We propose a structure from motion algorithm using lines as this feature possesses many advantageous characteristics over points, especially in urban environment. This method consists of linear motion estimation based on line correspondences, 3D reconstruction and bundle adjustment to refine the camera and structure parameters. Besides lines, points can be integrated in our translation estimation to improve its performance. The contributions of this thesis concern the applicability of the proposed method to any type of central projection cameras including fish-eye ones, the advantage of using line images, and the exploitation of both point and line features