Дисертації з теми "Multiple objects"
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1
Aboutalib, Sarah. "Multiple-Cue Object Recognition for Interactionable Objects." Research Showcase @ CMU, 2010. http://repository.cmu.edu/dissertations/19.
Анотація:
Category-level object recognition is a fundamental capability for the potential use of robots in the assistance of humans in useful tasks. There have been numerous vision-based object recognition systems yielding fast and accurate results in constrained environments. However, by depending on visual cues, these techniques are susceptible to object variations in size, lighting, rotation, and pose, all of which cannot be avoided in real video data. Thus, the task of object recognition still remains very challenging.
My thesis work builds upon the fact that robots can observe humans interacting with the objects in their environment. We refer to the set of objects, which can be involved in the interaction as `interactionable' objects. The interaction of humans with the `interactionable' objects provides numerous nonvisual cues to the identity of objects.
In this thesis, I will introduce a flexible object recognition approach called Multiple-Cue Object Recognition (MCOR) that can use multiple cues of any predefined type, whether they are cues intrinsic to the object or provided by observation of a human. In pursuit of this goal, the thesis will provide several contributions: A representation for the multiple cues including an object definition that allows for the flexible addition of these cues; Weights that reflect the various strength of association between a particular cue and a particular object using a probabilistic relational model, as well as object displacement values for localizing the information in an image; Tools for defining visual features, segmentation, tracking, and the values for the non-visual cues; Lastly, an object recognition algorithm for the incremental discrimination of potential object categories.
We evaluate these contributions through a number of methods including simulation to demonstrate the learning of weights and recognition based on an analytical model, an analytical model that demonstrates the robustness of the MCOR framework, and recognition results on real video data using a number of datasets including video taken from a humanoid robot (Sony QRIO), video captured from a meeting setting, scripted scenarios from outside universities, and unscripted TV cooking data.
Using the datasets, we demonstrate the basic features of the MCOR algorithm including its ability to use multiple cues of different types. We demonstrate the applicability of MCOR to an outside dataset. We show that MCOR has better recognition results over vision-only recognition systems, and show that performance only improves with the addition of more cue types.
2
Ramalingam, Chitra. "Modeling Multiple Granularities of Spatial Objects." Fogler Library, University of Maine, 2002. http://www.library.umaine.edu/theses/pdf/RamalingamC2002.pdf.
3
De, Vaal Jan Hendrik. "Metric reconstruction of multiple rigid objects." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/2892.
Анотація:
Thesis (MScEng (Mathematical Sciences. Applied Mathematics))--University of Stellenbosch, 2009.Engineers struggle to replicate the capabilities of the sophisticated human visual system. This thesis sets out to recover motion and 3D structure of multiple rigid objects up to a similarity. The motion of these objects are either recorded in a single video sequence, or images of the objects are recorded on multiple, di erent cameras. We assume a perspective camera model with optional provision for calibration information. The Structure from Motion (SfM) problem is addressed from a matrix factorization point of view. This leads to a reconstruction correct up to a projectivity of little use in itself. Using techniques from camera autocalibration the projectivity is upgraded to a similarity. This reconstruction is also applied to multiple objects through motion segmentation. The SfM system developed in this thesis is a batch-processing algorithm, requiring few frames for a solution and readily accepts images from very di erent viewpoints. Since a solution can be obtained with just a few frames, it can be used to initialize sequential methods with slower convergence rates, such as the Kalman lter. The SfM system is critically evaluated against an extensive set of motion sequences.
4
Thórhallsson, Torfi. "Symmetric objects in multiple affine views." Thesis, University of Oxford, 2000. http://ora.ox.ac.uk/objects/uuid:49ec4596-7086-4645-81f8-8dacf48b694a.
Анотація:
This thesis is concerned with the utilization of object symmety as a cue for segmentation and object recognition. In particular it investigates the problem of detecting 3D bilaterally symmetric objects from affine views. The first part of the thesis investigates the problem of detecting 3D bilateral symmetry within a scene from known point correspondences across two or more affine views. We begin by extending the notion of skewed symmetry to three dimensions, and give a definition in terms of degenerate structure that applies equally to an affine 3D structure or to point correspondences across two or more affine views. We then consider the effects of measurement errors on symmetry detection, and derive an optimal statistical test of degenerate structure, and thereby of 3D-skewed symmetry. We then move on to the problem of searching for 3D skewed symmetric sets within a larger scene. We discuss two approaches to the problem, both of which we have implemented, and we demonstrate fully automatic detection of 3D skewed symmetry on images of uncluttered scenes. We conclude the first part by investing means of verifying the presence of bilateral rather than skewed symmetry in the Euclidean space, by enforcing mutual consistency between multiple skewed symmetric sets, and by drawing on partial knowledge about the camera calibration. The second part of the thesis is concerned with the problem of obtaining feature correspondences across multiple affine views, as required for the detection of symmetry. In particular we investigate the geometric matching constraints that exist between affine views. We start by specilizing the four projective multifocal tensors to the affine case, and use these to carry the bulk of all known projective multi-view matching relations to affine views, unearthing some new relations in the process. Having done that, we address the problem of estimating the affine tensors. We provide a minimal set of constraints on the affine trifocal tensor, and search for ways of estimating the affine tensors from point and line correspondences.
5
Titsias, Michalis. "Unsupervised learning of multiple objects in images." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/776.
Анотація:
Developing computer vision algorithms able to learn from unsegmented images containing multiple objects is important since this is how humans constantly learn from visual experiences. In this thesis we consider images containing views of multiple objects and our task is to learn about each of the objects present in the images. This task can be approached as a factorial learning problem, where each image is explained by instantiating a model for each of the objects present with the correct instantiation parameters. A major problem with learning a factorial model is that as the number of objects increases, there is a combinatorial explosion of the number of configurations that need to be considered. We develop a greedy algorithm to extract object models sequentially from the data by making use of a robust statistical method, thus avoiding the combinatorial explosion. When we have video data, we greatly speed up the greedy algorithm by carrying out approximate tracking of the multiple objects in the scene. This method is applied to raw image sequence data and extracts the objects one at a time. First, the (possibly moving) background is learned, and moving objects are found at later stages. The algorithm recursively updates an appearance model so that occlusion is taken into account, and matches this model to the frames through the sequence. We apply this method to learn multiple objects in image sequences as well as articulated parts of the human body. Additionally, we learn a distribution over parts undergoing full affine transformations that expresses the relative movements of the parts. The idea of fitting a model to data sequentially using robust statistics is quite general and it can be applied to other models. We describe a method for training mixture models by learning one component at a time and thus building the mixture model in a sequential manner. We do this by incorporating an outlier component into the mixture model which allows us to fit just one data cluster by "ignoring" the rest of the clusters. Once a model is fitted we remove from consideration all the data explained by this model and then repeat the operation. This algorithm can be used to provide a sensible initialization of the mixture components when we train a mixture model.
6
Ye, Lin. "The Perception of Objects with Multiple Affordances." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1165554317.
7
Wallén, David Nikolas Alfred. "High precision detection of multiple rotating objects." Thesis, KTH, Mekatronik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-245195.
Анотація:
Denna avhandling har skrivits i sammarbete med en Stockholmsbaserat konst- och designstudio vid namn ''Humans since 1982'' som bygger och säljer modern högteknologisk konst till marknader världen över. Studion ville utföra forskning kring att utveckla och implementera ett system som detekterade och beräknade positionen av två roterande oberoende objekt monterade på två stegmotorer via en växellåda. Produkten där lösningen skulle implementeras ställde olika tekniska och designmässiga krav på implementationen. De viktigaste kraven var att lösningen skulle klara en noggrannhet på ±1° med en precision på 99.95 %. Hastigheten för objekten som detekterades var minst 50 [steg/sekund] och distansen mellan objekten och detektionsutrustning var minst 20 [mm]. En barriär av ett ometalliskt material skiljde objekten och motorerna samt den drivande elektroniken åt, vilket i kombination med en komplicerad växellåda förhindrade användandet av IR baserade lösningar, rotationsenkoders eller mekaniska kalibreringsmetoder. Olika möjliga tekniska lösningar i form av kapasitans- induktions- och radiobaserade detektionsmetoder undersöktes. En lösning baserat på Hall-element och permanenta Neodymium magneter föreslogs, designades, implementerades och testades. Två olika algoritmer för automatisk detektion och kalibrering föreslogs och testades. Den första algoritmen var baserad på att röra båda objekten samtidigt och den andra var baserad på att röra ett objekt i taget. Den andra algoritmen visades vara mest optimal med avseende på tid, robusthet och noggrannhet och efter implementation på hårdvaruplatformen (som bestod av en 32-bit ARM Cortex mikro kontroller) åstadkom den en noggrannhet på ± 0.8° med en precision på 99.97 %. Självkalibreringen tog 92.6 [s] och konsumerade i genomsnitt 34.56 % av processor cyklerna. Applikationen tog då upp 85.93 % av RAM-minnet och 13.74 % av flash minnet inkluderat ett realtidsoperativsystem samt bibliotek för att extrahera testdatan.This thesis project has been developed in conjunction with a Stockholm based art studio called ''Humans since 1982''. The studio builds and sells contemporary and highly technological luxury art pieces all over the world. The company wanted to perform research towards developing and implementing a solution that detected and determined the position of two independent objects being rotated by two stepper motors and a gearbox. This thesis investigates possible proximity sensor solutions and their applicability and accuracy for this application. The requirements of the solution are to perform detection of two rotating loads driven by stepper motors at about 50 [steps/second] at a distance of 20 [mm] from any sensing electronics within the accuracy of ±1° with a precision of 99.95 %. The loads were mounted in such a way that they were not in line of sight from the driving motor or electronics and a complex unmodifiable gearbox prevented simple solutions such as IR-based sensors, rotary encoders and mechanical stoppers to be used. Multiple detection options such as capacitive-, inductive-, and radio based methods were investigated. A technical solution based on Hall elements and permanent Neodymium magnets was proposed, designed, implemented and tested. Two algorithms for automatic load detection and calibration were proposed and tested. The first algorithm detected the loads while both were moving simultaneously and the second detected one load at a time. The second algorithm proved to be the best solution with respect to time, robustness and accuracy and it was able to achieve an accuracy of 0.8° at a precision of 99.97 % and it was implemented on the target embedded system. The self-calibration took 92.6 [s] with an average CPU utilization of 34.56 %, consumed 85.93 % of the MCU RAM and 13.74 % of the Flash memory including a real-time operating system and drivers for extraction of test data on a 32-bit ARM Cortex micro controller.
8
Muschter, Evelyn. "Constructing multiple objects across space and time." Doctoral thesis, Università degli studi di Trento, 2018. https://hdl.handle.net/11572/368612.
Анотація:
For us to interact with our environment we must have an understanding of the location and properties of the objects within it over time. Incoming stimuli from different sensory modalities continuously provide information. In order to create a coherent percept, it is necessary to combine these sensory signals in the brain into a single representation of an object or event. Temporal integration, the process of combining information over time is one important prerequisite for it. Likewise, multisensory integration, the process of combining information from different sensory modalities to generate a coherent percept is of great importance. Furthermore, as our environment is not static but dynamic it is necessary to combine sensory information over time and space. Despite, the ever-increasing neuroscientific results, much about the underlying brain mechanisms remains unknown. This thesis describes an effort of understanding how sensory information are integrated in the brain and what effects attention has on how we integrate multiple objects in space and time.
Chapter 1 introduces the reader to the existing literature on neural oscillations, specifically alpha band frequency, which is hypothesized to play a critical role in temporal processing and attention. This is followed by a review of the literature on temporal integration and the theoretical background of multisensory integration. The following chapters will report the three studies conducted: Chapter 2 describes the first study, a MEG study that investigates the role of alpha oscillations in temporal integration. Chapter 3 reports the second MEG study, which focuses the role of attention to modality in multisensory integration. Chapter 4 presents the third study, a behavioral oscillations study, which focuses on the role of neural oscillations in selective attention in a dynamic scene. Finally, Chapter 5 summarizes all the findings from this research.
9
Muschter, Evelyn. "Constructing multiple objects across space and time." Doctoral thesis, University of Trento, 2018. http://eprints-phd.biblio.unitn.it/2984/1/thesis_Evelyn_Muschter_final.pdf.
Анотація:
For us to interact with our environment we must have an understanding of the location and properties of the objects within it over time. Incoming stimuli from different sensory modalities continuously provide information. In order to create a coherent percept, it is necessary to combine these sensory signals in the brain into a single representation of an object or event. Temporal integration, the process of combining information over time is one important prerequisite for it. Likewise, multisensory integration, the process of combining information from different sensory modalities to generate a coherent percept is of great importance. Furthermore, as our environment is not static but dynamic it is necessary to combine sensory information over time and space. Despite, the ever-increasing neuroscientific results, much about the underlying brain mechanisms remains unknown. This thesis describes an effort of understanding how sensory information are integrated in the brain and what effects attention has on how we integrate multiple objects in space and time.
Chapter 1 introduces the reader to the existing literature on neural oscillations, specifically alpha band frequency, which is hypothesized to play a critical role in temporal processing and attention. This is followed by a review of the literature on temporal integration and the theoretical background of multisensory integration. The following chapters will report the three studies conducted: Chapter 2 describes the first study, a MEG study that investigates the role of alpha oscillations in temporal integration. Chapter 3 reports the second MEG study, which focuses the role of attention to modality in multisensory integration. Chapter 4 presents the third study, a behavioral oscillations study, which focuses on the role of neural oscillations in selective attention in a dynamic scene. Finally, Chapter 5 summarizes all the findings from this research.
10
Cichocki, Radoslaw. "Classification of objects in images based on various object representations." Thesis, Blekinge Tekniska Högskola, Avdelningen för programvarusystem, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-5774.
Анотація:
Object recognition is a hugely researched domain that employs methods derived from mathematics, physics and biology. This thesis combines the approaches for object classification that base on two features – color and shape. Color is represented by color histograms and shape by skeletal graphs. Four hybrids are proposed which combine those approaches in different manners and the hybrids are then tested to find out which of them gives best results.Mail the author at radoslaw.cichocki(at)gmail.com
11
Azizoglu, Suha Alp. "Time Domain Scattering From Single And Multiple Objects." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609413/index.pdf.
Анотація:
The importance of the T-matrix method is well-known when frequency domain scattering problems are of interest. With the relatively recent and wide-spread interest in time domain scattering problems, similar applications of the T-matrix method are expected to be useful in the time domain. In this thesis, the time domain spherical scalar wave functions are introduced, translational addition theorems for the time domain spherical scalar wave functions necessary for the solution of multiple scattering problems are given, and the formulation of time domain scattering of scalar waves by two spheres and by two scatterers of arbitrary shape is presented. The whole analysis is performed in the time domain requiring no inverse Fourier integrals to be evaluated. Scattering examples are studied in order to check the numerical accuracy, and demonstrate the utility of the expressions.
12
Xu, Jianqiu [Verfasser]. "Moving objects with multiple transportation modes / Jianqiu Xu." Hagen : Fernuniversität Hagen, 2012. http://d-nb.info/102515584X/34.
13
Tran, Tuan-Anh. "Multiple-input multiple-output optical wireless communications." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:094fbe23-88c3-49c4-b64b-a1de40674123.
Анотація:
Visible-light optical wireless communications (OWC) is a potential technology that can help resolve the crowdedness of the radio-frequency bands, whilst conveniently exploiting energy-saving light-emitting diodes (LEDs) as transmitters for both illumination and communications. Since there usually are many LEDs in a lighting unit, OWC has a multi- input multi-output (MIMO) geometry which, thanks to its channel diversity, can offer wireless local networks at data-rates many times higher than possible with single-channel systems. In such systems, MIMO-detection methods to separate the different optical channels play an important role in improving the system performance by helping reduce cross-talk between channels. To measure the performance of a particular geometry for MIMO communications, a simulation study, reported in this thesis, found that, amongst the signal- independent metrics, the condition number may be used as a rough predictor of the performance, whilst the channel Signal-to-Interference-and-Noise Ratio (SINR) is the most appropriate for geometry assessment. Combined with the fact that the overall performance of a MIMO system is mostly dominated by its worst channel, this indicates that the most effective way to improve the system performance is to maximise the worst channel’s SINR. One of the possible solutions to improving the SINRs is to use holograms to steer the transmitter images such that their distributions over the photo-detectors reduce overlaps. As LEDs emit partially-coherent light, the beam steering has to be carried out with partially- coherent illumination. By using two lenses to parallelise and collect partially-coherent light before and after the hologram, respectively, the source and image intensity distributions, and the autocorrelation of the hologram can be related in a succinct mathematical relationship. This leads to the development of three computational algorithms based on the autocorrelation function to obtain a quantised hologram with the desired beam-steering capability. These algorithms have their cost functions and performance comparison done at the hologram plane instead of the image plane, which therefore takes less time than traditional image-based methods. Specifically, one of these algorithms is able to save significant time over both the other autocorrelation-based algorithms and the direct binary-search, by 33% and by 50% respectively. A simulation-based study and a corresponding experiment, both reported in this thesis, found that the one of the proposed algorithms had poor power efficiency, whilst the other two were both highly effective in generating digital holograms with precise and power-efficient beam-steering performance. Of these two algorithms, one had superior time performance and was likely the best of the three proposed autocorrelation-based algorithms for generating beam-steering holograms. MIMO-OWC simulation also demonstrated the capability of using beam-steering holograms to design the channel and improve the system performance. Combining reported findings, a strategy can be devised to optimise the throughput of an imaging MIMO-OWC system for a given transmitted power.
14
Ahn, Yushin. "Object space matching and reconstruction using multiple images." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1213375997.
15
Sethuruman, Vijayashankar. "A hybrid technique for tracking network structured multiple deformable objects." Thesis, University of Nottingham, 2011. http://eprints.nottingham.ac.uk/12153/.
Анотація:
In this thesis, a novel hybrid approach for tracking variable numbers of network structured deformable objects is presented. The hybrid technique developed is a combination of the Network Snakes parametric active contours technique, and the Reversible Jump Markov Chain Monte Carlo (RJMCMC)-based particle filter approach. Additionally, a novel method for (semi-)automatic initialization of the network snakes is implemented. The proposed technique is applied to the real biological problem of tissue-level segmentation, and automatic tracking, of a network of cells in confocal images showing the roots of the model plant Arabidopsis thaliana. The Network Snake component is used to model the structure of cells in Arabidopsis roots, which are clustered together and delineated by shared object boundaries forming a network topology.The RJMCMC tracker is allowed to track the network node points over image sequences, and these tracked nodes are then used to control and reparameterise the topology of the network snakes at each time step. This is followed by energy minimization of the network snakes which refines the tracked nodes and cell boundaries to settle at the energy minimum. Thus the component techniques complement each other in the hybrid approach. A novel method of evaluating such network-structured multi-target tracking is also presented in this thesis, and is used to evaluate the developed tracking framework for accuracy and robustness using several real and synthetic time-varying and depth varying(z-stack) image sequences of growing Arabidopsis roots.
16
Abrahamsson, Anton. "Three dimensional tracking of multiple objects using digital holographic microscopy." Thesis, Umeå universitet, Institutionen för fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-124722.
17
Li, Ran. "Optical multiple input and multiple output (MIMO) in multimode fibre." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:1770da43-e93b-462b-866f-beb5f972ce06.
Анотація:
Recently, there has been a dramatic increase in the amount of data transmission within short range local area networks (LAN). Multimode fibre (MMF) is widely used in local area networks because of its coupling and alignment along with the low cost of related components. Graded index MMF has become common due to the reduction in pulse spreading; however, as demands for high bandwidth increase towards a future gigabit rate network, the typical MMF using conventional transmission methods will not be suitable. Meanwhile, this increasing demand for high speed data transmission will soon reach the Shannon capacity limit of single mode fibres. After multiple input and multiple output (MIMO) technology was successfully used in wireless communication, the researcher realised that the same idea could also be applied to an optical fibre network. Optical MIMO techniques are gaining interest in order to create parallel channels over orthogonal modes in a MMF or a few mode fibre (FMF). This approach could lead to a significant increase in the bandwidth distance product and be employed in the next 40Gb/s or even 100Gb/s optical fibre transmission systems. Generally speaking, optical MIMO appears to be the best solution to the bandwidth limitation problem in either short distance MMF or long distance FMF systems. This thesis focuses on designing a simple, cost-effective, and energy efficient optical MIMO system based on MMFs. This proposed system can be realised by combining radial offset launching and annular multi-segment detectors. First, in the initial work, we performed a theoretical and numerical study of the key impairments of MMFs, and the mode propagation in an MMF was analysed mathematically. The variation in electrical field intensity for linearly polarised (LP) modes in the core region of an MMF and the analytical solutions for power coupling coefficients in either radial offset launching or centre launching were presented. In addition, the modal time delays, impulse response, and transfer function were all introduced. Subsequently, the near field intensity pattern (NFP) was simulated at the output facet of the MMF, which indicated that the overall NFP suffered from blurring when it contained mode mixing, and that the intensity pattern was particularly sensitive to the random phase. According to the spatial distribution of the NFP, the annular detector can be exploited more efficiently. All of the results were calculated and plotted using the MATLAB program. Secondly, the optical MIMO model in the multimode fibre was briefly summarised, including the MIMO channel matrix H expression, a mathematical expression of optical MIMO capacity, MIMO channel estimation and an equalization method. Two metrics can be used to characterise the MIMO channel performance: condition number and crosstalk at each receiver. The numerical results demonstrated that the new type of annular multi-segment detector exhibits superior performance compared to the conventional multiple single mode fibre (SMF) detectors, making them attractive for future optical MIMO systems. Finally, the core work of this thesis can be divided into two parts: the modelling of a 10Gb/s intensity modulation direct detection (IM-DD) optical MIMO MMF system; and the modelling of an advanced 10Gb/s coherent differential phase shift keying (DPSK) MIMO FMF system. In both simulation systems, the important transmission parameters of intra-group mode mixing, modal dispersion, chromatic dispersion, and mode attenuation were considered and discussed in detail. In the IM-DD optical MIMO system, the optimization of the transceiver can be based upon the laser spot size and the power flux distribution emitted by the transmitter. Results from the simulation showed that the intra-group mode mixing had a limited impact on system performance, and due to its inability to compensate for linear impairments, the IM-DD optical MIMO was not favourable for long distance transmission systems. Nevertheless, the new type of optical fibre FMF seems to be the most promising candidate for use in long haul transmission systems. Therefore, the well-known DPSK modulation format in conjugation with the coherent detection deployed in FMF was studied. Both heterodyne and intradyne detection schemes were analysed followed by mathematical derivation and numerical simulation; the results illustrated that similar system performances can be achieved in both schemes. Meanwhile, the coherent DPSK simulation results also demonstrated that the linear impairments were almost compensated by the frequency domain MIMO equalization process, which resulted in system performance being independent to transmission distance for up to 10km. This advantage proved that the coherent optical DPSK MIMO system can be employed in long haul networks. As with an IM-DD optical MIMO system, optimization of a coherent MIMO system was also possible. However, in contrast to the optimization of an IM-DD MIMO system, a trade-off had to be made between sufficient spatial diversity at the transceiver and differential modal delay caused by modal dispersion; consequently, the numerical results showed that the proposed coherent optical DPSK MIMO gained reasonable good results without using any active device, such as a spatial light modulator and a mode converter. In conclusion, this proposed optical MIMO system provided easy implementation and integration and is feasible for use in future optical communication systems.
18
Kivrikis, Andreas, and Johan Tjernström. "Development and Evaluation of Multiple Objects Collision Mitigation by Braking Algorithms." Thesis, Linköping University, Department of Electrical Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-2676.
Анотація:
A CMbB system is a system that with the help of sensors in the front of a car detects when a collision in unavoidable. When a situation like that is detected, the brakes are activated. The decision of whether to activate the brakes or not is taken by a piece of software called a decision maker. This software continuously checks for routes that would avoid an object in front of the car and as long as a path is found nothing is done. Volvo has been investigating several different CMbB-systems, and the research done by Volvo has previously focused on decision makers that only consider one object in front of the car. By instead taking all present objects in consideration, it should be possible to detect an imminent collision earlier. Volvo has developed some prototypes but needed help evaluating their performance.
As part of this thesis a testing method was developed. The idea was to test as many cases as possible but as the objects’ possible states increase, the number of test cases quickly becomes huge. Different ways of removing irrelevant test cases were developed and when these ideas were realized in a test bench, it showed that about 98 % of the test cases could be removed.
The test results showed that there is clearly an advantage to consider many objects if the cost of increased complexity in the decision maker is not too big. However, the risk of false alarms is high with the current decision makers and several possible improvements have therefore been suggested.
19
Toyoura, Masahiro. "3D shape reconstruction from multiple silhouettes for objects in rigid motion." 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/135999.
20
Cleasen, Stefan. "A verification and display system for multiple modality DICOM 3.0 objects." Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391942.
21
Sethuraman, Vijayashankar. "A hybrid technique for tracking network structured multiple deformable objects tracking." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546700.
22
Lin, Eugene S. (Eguene Seichi). "Recovery of 3-D shape of curved objects from multiple views." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/41372.
23
Singh, Gurjashan. "Health Monitoring of Round Objects using Multiple Structural Health Monitoring Techniques." FIU Digital Commons, 2010. http://digitalcommons.fiu.edu/etd/330.
Анотація:
Structural Health Monitoring (SHM) techniques are widely used in a number of Non – destructive Evaluation (NDE) applications. There is a need to develop effective techniques for SHM, so that the safety and integrity of the structures can be improved. Two most widely used SHM methods for plates and rods use either the spectrum of the impedances or monitor the propagation of lamb waves. Piezoelectric wafer – active sensors (PWAS) were used for excitation and sensing. In this study, surface response to excitation (SuRE) and Lamb wave propagation was monitored to estimate the integrity of the round objects including the pipes, tubes and cutting tools. SuRE obtained the frequency response by applying sweep sine wave to surface. The envelope of the received signal was used to detect the arrival of lamb waves to the sensor. Both approaches detect the structural defects of the pipes and tubes and the wear of the cutting tool.
24
Sarkar, Biplab. "Modeling and manufacturing of multiple featured objects based on measurement data /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487757723996478.
25
Mellado, Nicolas. "Analysis of 3D objects at multiple scales : application to shape matching." Thesis, Bordeaux 1, 2012. http://www.theses.fr/2012BOR14685/document.
Анотація:
Depuis quelques années, l’évolution des techniques d’acquisition a entraîné une généralisation de l’utilisation d’objets 3D très dense, représentés par des nuages de points de plusieurs millions de sommets. Au vu de la complexité de ces données, il est souvent nécessaire de les analyser pour en extraire les structures les plus pertinentes, potentiellement définies à plusieurs échelles. Parmi les nombreuses méthodes traditionnellement utilisées pour analyser des signaux numériques, l’analyse dite scale-space est aujourd’hui un standard pour l’étude des courbes et des images. Cependant, son adaptation aux données 3D pose des problèmes d’instabilité et nécessite une information de connectivité, qui n’est pas directement définie dans les cas des nuages de points. Dans cette thèse, nous présentons une suite d’outils mathématiques pour l’analyse des objets 3D, sous le nom de Growing Least Squares (GLS). Nous proposons de représenter la géométrie décrite par un nuage de points via une primitive du second ordre ajustée par une minimisation aux moindres carrés, et cela à pour plusieurs échelles. Cette description est ensuite derivée analytiquement pour extraire de manière continue les structures les plus pertinentes à la fois en espace et en échelle. Nous montrons par plusieurs exemples et comparaisons que cette représentation et les outils associés définissent une solution efficace pour l’analyse des nuages de points à plusieurs échelles. Un défi intéressant est l’analyse d’objets 3D acquis dans le cadre de l’étude du patrimoine culturel. Dans cette thèse, nous nous étudions les données générées par l’acquisition des fragments des statues entourant par le passé le Phare d’Alexandrie, Septième Merveille du Monde. Plus précisément, nous nous intéressons au réassemblage d’objets fracturés en peu de fragments (une dizaine), mais avec de nombreuses parties manquantes ou fortement dégradées par l’action du temps. Nous proposons un formalisme pour la conception de systèmes d’assemblage virtuel semi-automatiques, permettant de combiner à la fois les connaissances des archéologues et la précision des algorithmes d’assemblage. Nous présentons deux systèmes basés sur cette conception, et nous montrons leur efficacité dans des cas concretsOver the last decades, the evolution of acquisition techniques yields the generalization of detailed 3D objects, represented as huge point sets composed of millions of vertices. The complexity of the involved data often requires to analyze them for the extraction and characterization of pertinent structures, which are potentially defined at multiple scales. Amongthe wide variety of methods proposed to analyze digital signals, the scale-space analysis istoday a standard for the study of 2D curves and images. However, its adaptation to 3D dataleads to instabilities and requires connectivity information, which is not directly availablewhen dealing with point sets.In this thesis, we present a new multi-scale analysis framework that we call the GrowingLeast Squares (GLS). It consists of a robust local geometric descriptor that can be evaluatedon point sets at multiple scales using an efficient second-order fitting procedure. We proposeto analytically differentiate this descriptor to extract continuously the pertinent structuresin scale-space. We show that this representation and the associated toolbox define an effi-cient way to analyze 3D objects represented as point sets at multiple scales. To this end, we demonstrate its relevance in various application scenarios.A challenging application is the analysis of acquired 3D objects coming from the CulturalHeritage field. In this thesis, we study a real-world dataset composed of the fragments ofthe statues that were surrounding the legendary Alexandria Lighthouse. In particular, wefocus on the problem of fractured object reassembly, consisting of few fragments (up to aboutten), but with missing parts due to erosion or deterioration. We propose a semi-automaticformalism to combine both the archaeologist’s knowledge and the accuracy of geometricmatching algorithms during the reassembly process. We use it to design two systems, andwe show their efficiency in concrete cases
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Tsogkas, Stavros. "Mid-level representations for modeling objects." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC012/document.
Анотація:
Dans cette thèse, nous proposons l'utilisation de représentations de niveau intermédiaire, et en particulier i) d'axes médians, ii) de parties d'objets, et iii) des caractéristiques convolutionnels, pour modéliser des objets.La première partie de la thèse traite de détecter les axes médians dans des images naturelles en couleur. Nous adoptons une approche d'apprentissage, en utilisant la couleur, la texture et les caractéristiques de regroupement spectral pour construire un classificateur qui produit une carte de probabilité dense pour la symétrie. Le Multiple Instance Learning (MIL) nous permet de traiter l'échelle et l'orientation comme des variables latentes pendant l'entraînement, tandis qu'une variante fondée sur les forêts aléatoires offre des gains significatifs en termes de temps de calcul.Dans la deuxième partie de la thèse, nous traitons de la modélisation des objets, utilisant des modèles de parties déformables (DPM). Nous développons une approche « coarse-to-fine » hiérarchique, qui utilise des bornes probabilistes pour diminuer le coût de calcul dans les modèles à grand nombre de composants basés sur HOGs. Ces bornes probabilistes, calculés de manière efficace, nous permettent d'écarter rapidement de grandes parties de l'image, et d'évaluer précisément les filtres convolutionnels seulement à des endroits prometteurs. Notre approche permet d'obtenir une accélération de 4-5 fois sur l'approche naïve, avec une perte minimale en performance.Nous employons aussi des réseaux de neurones convolutionnels (CNN) pour améliorer la détection d'objets. Nous utilisons une architecture CNN communément utilisée pour extraire les réponses de la dernière couche de convolution. Nous intégrons ces réponses dans l'architecture DPM classique, remplaçant les descripteurs HOG fabriqués à la main, et nous observons une augmentation significative de la performance de détection (~14.5% de mAP).Dans la dernière partie de la thèse nous expérimentons avec des réseaux de neurones entièrement convolutionnels pous la segmentation de parties d'objets.Nous réadaptons un CNN utilisé à l'état de l'art pour effectuer une segmentation sémantique fine de parties d'objets et nous utilisons un CRF entièrement connecté comme étape de post-traitement pour obtenir des bords fins.Nous introduirons aussi un à priori sur les formes à l'aide d'une Restricted Boltzmann Machine (RBM), à partir des segmentations de vérité terrain.Enfin, nous concevons une nouvelle architecture entièrement convolutionnel, et l'entraînons sur des données d'image à résonance magnétique du cerveau, afin de segmenter les différentes parties du cerveau humain.Notre approche permet d'atteindre des résultats à l'état de l'art sur les deux types de donnéesIn this thesis we propose the use of mid-level representations, and in particular i) medial axes, ii) object parts, and iii)convolutional features, for modelling objects.The first part of the thesis deals with detecting medial axes in natural RGB images. We adopt a learning approach, utilizing colour, texture and spectral clustering features, to build a classifier that produces a dense probability map for symmetry. Multiple Instance Learning (MIL) allows us to treat scale and orientation as latent variables during training, while a variation based on random forests offers significant gains in terms of running time.In the second part of the thesis we focus on object part modeling using both hand-crafted and learned feature representations. We develop a coarse-to-fine, hierarchical approach that uses probabilistic bounds for part scores to decrease the computational cost of mixture models with a large number of HOG-based templates. These efficiently computed probabilistic bounds allow us to quickly discard large parts of the image, and evaluate the exact convolution scores only at promising locations. Our approach achieves a $4times-5times$ speedup over the naive approach with minimal loss in performance.We also employ convolutional features to improve object detection. We use a popular CNN architecture to extract responses from an intermediate convolutional layer. We integrate these responses in the classic DPM pipeline, replacing hand-crafted HOG features, and observe a significant boost in detection performance (~14.5% increase in mAP).In the last part of the thesis we experiment with fully convolutional neural networks for the segmentation of object parts.We re-purpose a state-of-the-art CNN to perform fine-grained semantic segmentation of object parts and use a fully-connected CRF as a post-processing step to obtain sharp boundaries.We also inject prior shape information in our model through a Restricted Boltzmann Machine, trained on ground-truth segmentations.Finally, we train a new fully-convolutional architecture from a random initialization, to segment different parts of the human brain in magnetic resonance image data.Our methods achieve state-of-the-art results on both types of data
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Koller-Meier, Esther Bettina. "Extending the condensation algorithm for tracking multiple objects in range image sequences /." [S.l.] : [s.n.], 2000. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=13548.
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Gallardo, Mathias. "Contributions to Monocular Deformable 3D Reconstruction : Curvilinear Objects and Multiple Visual Cues." Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC021/document.
Анотація:
La reconstruction 3D monoculaire déformable est le problème général d'estimation de forme 3D d'un objet déformable à partir d'images 2D. Plusieurs scénarios ont émergé : le Shape-from-Template (SfT) et le Non-Rigid Structure-from-Motion (NRSfM) sont deux approches qui ont été grandement étudiées pour leur applicabilité. La première utilise une seule image qui montre un objet se déformant et un patron (une forme 3D texturée de l'objet dans une pose de référence). La seconde n'utilise pas de patron, mais utilise plusieurs images et estime la forme 3D dans chaque image. Les deux approches s'appuient sur le mouvement de points de correspondances entre les images et sur des a priori de déformations, restreignant ainsi leur utilisation à des surfaces texturées qui se déforment de manière lisse. Cette thèse fait avancer l'état de l'art du SfT et du NRSfM dans deux directions. La première est l'étude du SfT dans le cas de patrons 1D (c’est-à-dire des courbes comme des cordes et des câbles). La seconde direction est le développement d'algorithmes de SfT et de NRSfM qui exploitent plusieurs indices visuels et qui résolvent des cas réels et complexes non-résolus précédemment. Nous considérons des déformations isométriques et reconstruisons la partie extérieure de l'objet. Les contributions techniques et scientifiques de cette thèse sont divisées en quatre parties.La première partie de cette thèse étudie le SfT curvilinéaire, qui est le cas du patron curvilinéaire plongé dans un espace 2D ou 3D. Nous proposons une analyse théorique approfondie et des solutions pratiques pour le SfT curvilinéaire. Malgré son apparente simplicité, le SfT curvilinéaire s'est avéré être un problème complexe : il ne peut pas être résolu à l'aide de solutions locales non-holonomes d'une équation différentielle ordinaire et ne possède pas de solution unique, mais un nombre fini de solutions ambiguës. Une contribution technique majeure est un algorithme basé sur notre théorie, qui génère toutes les solutions ambiguës. La deuxième partie de cette thèse traite d'une limitation des méthodes de SfT : la reconstruction de plis. Cette limitation vient de la parcimonie de la contrainte de mouvement et de la régularisation. Nous proposons deux contributions qui s'appuient sur un cadre de minimisation d'énergie non-convexe. Tout d'abord, nous complétons la contrainte de mouvement avec une contrainte robuste de bord. Ensuite, nous modélisons implicitement les plis à l'aide d'une représentation dense de la surface basée maillage et d'une contrainte robuste de lissage qui désactive automatiquement le lissage de la courbure sans connaître a priori la position des plis.La troisième partie de cette thèse est dédiée à une autre limitation du SfT : la reconstruction de surfaces peu texturées. Cette limitation vient de la difficulté d'obtenir des correspondances (parcimonieuses ou denses) sur des surfaces peu texturées. Comme l'ombrage révèle les détails sur des surfaces peu texturées, nous proposons de combiner l'ombrage avec le SfT. Nous présentons deux contributions. La première est une initialisation en cascade qui estime séquentiellement la déformation de la surface, l'illumination de la scène, la réponse de la caméra et enfin les albédos de la surface à partir d'images monoculaires où la surface se déforme. La seconde est l'intégration de l'ombrage à notre précédent cadre de minimisation d'énergie afin de raffiner simultanément les paramètres photométriques et de déformation.La dernière partie de cette thèse relâche la connaissance du patron et aborde deux limitations du NRSfM : la reconstruction de surfaces peu texturées avec des plis. Une contribution majeure est l'extension du second cadre d'optimisation pour la reconstruction conjointe de la forme 3D de la surface sur toutes les images d'entrée et des albédos de la surface sans en connaître un patronMonocular deformable 3D reconstruction is the general problem of recovering the 3D shape of a deformable object from monocular 2D images. Several scenarios have emerged: the Shape-from-Template (SfT) and the Non-Rigid Structure-from-Motion (NRSfM) are two approaches intensively studied for their practicability. The former uses a single image depicting the deforming object and a template (a textured 3D shape of this object in a reference pose). The latter does not use a template, but uses several images and recovers the 3D shape in each image. Both approaches rely on the motion of correspondences between the images and deformation priors, which restrict their use to well-textured surfaces which deform smoothly. This thesis advances the state-of-the-art in SfT and NRSfM in two main directions. The first direction is to study SfT for the case of 1D templates (i.e. curved, thin structures such as ropes and cables). The second direction is to develop algorithms in SfT and NRSfM that exploit multiple visual cues and can solve complex, real-world cases which were previously unsolved. We focus on isometric deformations and reconstruct the outer part of the object. The technical and scientific contributions of this thesis are divided into four parts. The first part of this thesis studies the case of a curvilinear template embedded in 2D or 3D space, referred to Curve SfT. We propose a thorough theoretical analysis and practical solutions for Curve SfT. Despite its apparent simplicity, Curve SfT appears to be a complex problem: it cannot be solved locally using exact non-holonomic partial differential equation and is only solvable up to a finite number of ambiguous solutions. A major technical contribution is a computational solution based on our theory, which generates all the ambiguous solutions.The second part of this thesis deals with a limitation of SfT methods: reconstructing creases. This is due to the sparsity of the motion constraint and regularization. We propose two contributions which rely on a non-convex energy minimization framework. First, we complement the motion constraint with a robust boundary contour constraint. Second, we implicitly model creases with a dense mesh-based surface representation and an associated robust smoothing constraint, which deactivates curvature smoothing automatically where needed, without knowing a priori the crease location. The third part of this thesis is dedicated to another limitation of SfT: reconstructing poorly-textured surfaces. This is due to correspondences which cannot be obtained so easily on poorly-textured surfaces (either sparse or dense). As shading reveals details on poorly-textured surfaces, we propose to combine shading and SfT. We have two contributions. The first is a cascaded initialization which estimates sequentially the surface's deformation, the scene illumination, the camera response and then the surface albedos from deformed monocular images. The second is to integrate shading to our previous energy minimization framework for simultaneously refining deformation and photometric parameters.The last part of this thesis relaxes the knowledge of the template and addresses two limitations of NRSfM: reconstructing poorly-textured surfaces with creases. Our major contribution is an extension of the second framework to recover jointly the 3D shapes of all input images and the surface albedos without any template
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Bowyer, Robert O. "Multiple order models in predictive control." Thesis, University of Oxford, 1998. http://ora.ox.ac.uk/objects/uuid:a5f48d14-0250-4fc6-bb6f-7b43659930e8.
Анотація:
Predictive control has attracted much attention from both industry and academia alike due to its intuitive time domain formulation and since it easily affords adaption. The time domain formulation enables the user to build in prior knowledge of the operating constraints and thus the process can be controlled more efficiently, and the adaptive mechanism provides tighter control for systems whose behaviour changes with time. This thesis presents a fusion of technologies for dealing with the more practical aspects of obtaining suitable models for predictive control, especially in the adaptive sense. An accurate model of the process to be controlled is vital to the success of a predictive control scheme, and most the of work to date has assumed that this model is of fixed order, a restriction which can lead to poor controller performance associated with under/overparameterisation of the estimated model. To overcome this restriction a strategy which estimates both the parameters and the order of a linear model of the time-varying plant online is suggested. This Multiple Model Least-Squares technique is based on the recent work of Niu and co-workers who have ingeniously extended Bierman's method of UD updating so that, with only a small change to the existing UD update code, a wealth of additional information can be obtained directly from the U and D matrices including estimates of all the lower order models and their loss functions. The algorithm is derived using Clarke's Lagrange multiplier approach leading to a neater derivation and possibly a more direct understanding of Niu's Augmented UD Identification algorithm. An efficient and robust forgetting mechanism is then developed by analysing the properties of the continuous-time differential equations corresponding to existing parameter tracking methods. The resulting Multiple Model Recursive Least-Squares estimator is also ported to the δ-domain in order to obtain models for predictive controllers that employ fast sampling. The MMRLS estimator is then used in an adaptive multiple model based predictive controller for a coupled tanks system to compare performance with the fixed model order case.
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Dahl, Andrew. "Methods to jointly analyze multiple phenotypes." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:ed466a17-e96f-482b-b164-aa7ceefd94d4.
Анотація:
Linear mixed models (LMMs) have re-emerged as a central tool in statistical genetics. Fixed effects capture genetic variants tested for association. Random effects leverage aggregate relatedness while remaining agnostic to specific genetic mechanisms, naturally modeling heritability and controlling for polygenic background and confounding from population or family structure in genome-wide association studies (GWAS). Multiple random effects can partition heritability amongst many biologically meaningful variance components (VCs). Concurrently, genetic studies have begun to analyze multiple traits. This can improve power by adding data and can inform the path from genotype to phenotype, e.g. with graphical models, pleiotropy detection or endophenotyping. Multi-trait analyses are natural for biobanks and high-throughput phenotypic measurements like gene expression, medical images or metabolites. Following these advances, this thesis develops three multi-trait mixed models. phenix imputes missing phenotype data by modifying probabilistic matrix factorization to incorporate genetic relatedness. General linear mixed models (GLMMs) generalize and unify multi-VC, multi-trait and likelihood-penalized mixed models. Finally, compressive mixed models (CMMs) combine the two, obtaining the imputation and computational benefits of phenix and the heritability estimation and multi-VC capabilities of GLMMs. phenix essentially always outperforms all competitors in imputation and can improve GWAS power. GLMMs accurately estimate heritability despite (measured) confounders, can improve phenotype prediction, and increase gene-based, multi-trait association signal. CMMs regularly improve prediction, scale to thousands of phenotypes, and can uncover plausible GWAS hits entirely missed by LMMs. Altogether, multi-trait mixed models are invaluable for intrinsically multitrait tasks, like phenotype imputation and low-rank decomposition, and, surprisingly, can be much faster than LMMs; however, I find only small, and inconsistent, benefits for single-trait-oriented objectives like heritability estimation and out-of-sample prediction. The challenges in this thesis are primarily computational. Naively, multi-trait approaches model an N × P matrix of P phenotypes measured on N samples as a long Gaussian vector, inducing prohibitive O(N3P3) computations. Fortunately, the parsimonious matrix normals underlying mixed models enable simpler O(N3+P3) expressions. This is summarized by a new decomposition for positive semidefinite tensor products that, under a crucial assumption, facilitates cheap evaluation of ubiquitous low-level operations like multiplication.
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Simpson, Edwin Daniel. "Combined decision making with multiple agents." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:f5c9770b-a1c9-4872-b0dc-1bfa28c11a7f.
Анотація:
In a wide range of applications, decisions must be made by combining information from multiple agents with varying levels of trust and expertise. For example, citizen science involves large numbers of human volunteers with differing skills, while disaster management requires aggregating information from multiple people and devices to make timely decisions. This thesis introduces efficient and scalable Bayesian inference for decision combination, allowing us to fuse the responses of multiple agents in large, real-world problems and account for the agents’ unreliability in a principled manner. As the behaviour of individual agents can change significantly, for example if agents move in a physical space or learn to perform an analysis task, this work proposes a novel combination method that accounts for these time variations in a fully Bayesian manner using a dynamic generalised linear model. This approach can also be used to augment agents’ responses with continuous feature data, thus permitting decision-making when agents’ responses are in limited supply. Working with information inferred using the proposed Bayesian techniques, an information-theoretic approach is developed for choosing optimal pairs of tasks and agents. This approach is demonstrated by an algorithm that maintains a trustworthy pool of workers and enables efficient learning by selecting informative tasks. The novel methods developed here are compared theoretically and empirically to a range of existing decision combination methods, using both simulated and real data. The results show that the methodology proposed in this thesis improves accuracy and computational efficiency over alternative approaches, and allows for insights to be determined into the behavioural groupings of agents.
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Vörös, András. "The emergence of multiple status systems in adolescent communities : a multiplex network theory of group formation." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:9590194f-84e9-4548-b1fe-cf2f64ffc329.
Анотація:
How do informal groups emerge in adolescent communities? What distinguishes a group from just a set of students? Who will end up together in a group and who will be left out? Why are there more groups in some classrooms and fewer in others? What determines whether these groups overlap in their members or they are completely segregated, perhaps antagonistic? While a huge body of research in sociology and social psychology focuses on these questions, an integrated approach that is able to answer all of them is yet to be developed. Without realizing that these five issues are interrelated, we cannot hope to understand how groups influence individuals and how they shape our communities. This thesis proposes an integrative theory of informal group formation in communities. Based on the tradition of Social Network Analysis, it develops a framework in which interpersonal relations and reputations are formed through a process called informal status production. Groups emerge from this micro-process by the alignment of positive relations and agreement in peer-perceptions between actors. The main micro-mechanisms predicted by the theory are tested on a unique longitudinal network dataset from school classrooms. To this end, a new empirical procedure was developed, by which a few aggregated networks can be constructed from tens of relational items. This allows the analysis of rich network data with several relational dimensions. The empirical studies of multiplex network dynamics confirm that there are strong interdependencies between friendships and perceptions. Students who agree about their peers tend to become friends, but more so when they hold a minority opinion in the class. This contributes to group formation. Friends also influence each other's perceptions, but we manage to show that the presence of groups around them interferes with this process by moderating the influence of individual peers.
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Flint, Alexander John. "Geometric context from single and multiple views." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:f6c11e50-c059-4254-9dfc-5cbd2ee8147f.
Анотація:
In order for computers to interact with and understand the visual world, they must be equipped with reasoning systems that include high–level quantities such as objects, actions, and scenes. This thesis is concerned with extracting such representations of the world from visual input. The first part of this thesis describes an approach to scene understanding in which texture characteristics of the visual world are used to infer scene categories. We show that in the context of a moving camera, it is common to observe images containing very few individually salient image regions, yet overall texture structure often allows our system to derive powerful contextual cues about the environment. Our approach builds on ideas from texture recognition, and we show that our algorithm out–performs the well–known Gist descriptor on several classification tasks. In the second part of this thesis we we are interested in scene understanding in the context of multiple calibrated views of a scene, as might be obtained from a Structure–from–Motion or Simultaneous Localization and Mapping (SLAM) system. Though such systems are capable of localizing the camera robustly and efficiently, the maps produced are typically sparse point-clouds that are difficult to interpret and of little use for higher–level reasoning tasks such as scene understanding or human-machine interaction. In this thesis we begin to address this deficiency, presenting progress towards modeling scenes using semantically meaningful primitives such as floor, wall, and ceiling planes. To this end we adopt the indoor Manhattan representation, which was recently proposed for single–view reconstruction. This thesis presents the first in–depth description and analysis of this model in the literature. We describe a probabilistic model relating photometric features, stereo photo–consistencies, and 3D point clouds to Manhattan scene structure in a Bayesian framework. We then present a fast dynamic programming algorithm that solves exact MAP inference in this model in time linear in image size. We show detailed comparisons with the state–of–the art in both the single– and multiple–view contexts. Finally, we present a framework for learning within the indoor Manhattan hypothesis class. Our system is capable of extrapolating from labelled training examples to predict scene structure for unseen images. We cast learning as a structured prediction problem and show how to optimize with respect to two realistic loss functions. We present experiments in which we learn to recover scene structure from both single and multiple views — from the perspective of our learning algorithm these problems differ only by a change of feature space. This work constitutes one of the most complicated output spaces (in terms of internal constraints) yet considered within a structure prediction framework.
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Papaioannou, Savvas. "Tracking multiple mobile devices in CCTV-enabled areas." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:c159e6e8-d6b1-4d44-a319-54d6ca5947f1.
Анотація:
Over the last decade, we have witnessed an unprecedented interest in indoor positioning technologies, with a variety of solutions developed in academic and industrial research labs. Although the field has reached a significant level of maturity, there is still no dominant solution and, as a consequence, positioning services are still lacking in many buildings. In order for a solution to be widely implemented and adopted, two key requirements must be satisfied: low cost and high accuracy. The dichotomy between cost and accuracy has fragmented the technology landscape, leading to a plethora of competing solutions that cannot satisfy both requirements simultaneously. The key objective of this thesis is to investigate how to unify the two disparate camps, providing high positioning accuracy with very low cost. Many approaches have tried to achieve this goal by fusing different sensor modalities. However, the majority of existing work has only investigated how to fuse sequences of measurements for which the associations with the targets are known (i.e. device personal data). Sensor fusion techniques that combine device personal data and anonymous sensor streams (where the associations between the measurements and the targets are not known) remain under-explored as of today. In this thesis, we investigate how to efficiently combine device sensor data and anonymous sensor streams from various sensor modalities in order to build low cost and high accuracy positioning systems. By combining these two types of sensor modalities in one system we see a great potential in designing cost-effective and accurate positioning systems for challenging environments such as for tracking people in highly dynamic industrial settings. Our goal is to design a multi-target multi-sensor tracking framework which will utilise existing sensor infrastructure found in industrial environments and large public buildings (e.g museums) in order to provide reliable positioning services.
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Yates, Richard. "Genetic, pathologic, and radiographic correlations in multiple sclerosis." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:a2ae7907-3124-4c65-83fc-72fa00fd45ed.
Анотація:
Substantial evidence suggests that cortical tissue injury plays a key role in the progression of permanent disability in multiple sclerosis (MS). A greater knowledge of factors that drive pathology in the MS cortex is therefore desperately needed in order to develop novel medicines that can ameliorate disease burden in the progressive stage. In the current thesis, we undertake a robust and quantitative analysis of motor cortical neuropathology in a large cohort of post-mortem MS cases. We find that genetic variation at the HLA-DRB1 locus is associated with the extent of cortical demyelinating and inflammatory disease, especially in younger cases. Relevant to cortical neurodegeneration, we identify fibrinogen deposition as a novel component of MS cortical pathology that associates with neuronal loss, show that carriage of HLA- DRB1*15 has a critical impact on the relationship between microglia/macrophage inflammation and cortical neuronal density, and demonstrate disease-relevant changes to motor cortical neuronal glutamic acid decarboxylase expression. Given the myriad subcortical connections of the motor cortex, we have also undertaken an extensive assessment of corticospinal tract lesional burden throughout the neuraxis and find that motor cortical neurodegeneration appears independent of subcortical tissue injury. Taken together, this thesis highlights the importance of genetic variation at the HLA- DRB1 locus to cortical pathologic outcome, and the fundamental contribution of fibrinogen deposition and cortical parenchymal inflammatory factors to neuronal fate.
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Jenkins, Michael. "Attending to multiple objects : the dynamics of attentional control in multi-target stimulus arrays." Thesis, Birkbeck (University of London), 2018. http://bbktheses.da.ulcc.ac.uk/302/.
Анотація:
In this thesis, the cognitive and neural mechanisms of attentional control are examined, with a specific focus on investigating the temporal dynamics of these mechanisms in scenarios where multiple objects must be attended. Event-related potential (ERP) measures are used to track the continuous time course of visual responses in the brain, and the N2pc component is employed as a marker for the attentional selection of target objects. Two broad lines of research are presented. The first line examines the attentional selection of multiple rapidly presented instances of a single target object defined by varying properties, revealing very rapid and flexible brain responses triggered independently to the appearance of each target. The second line investigates the speed and qualitative nature of strictly serial attention shifts when they are guided by stimulus features or only by location information, revealing the availability of different attentional control mechanisms for these different shifts. In the context of these findings, this thesis attempts to improve the cognitive and neural understanding of how attentional control operates. The attentional template, a working memory representation of currently task-relevant properties, is proposed to flexibly allow for the preparatory enhancement of the activity of neurons that respond to these target-defining properties, allowing for the independent allocation of attention to each instance of a target in real-time. The properties that can be maintained by the attentional template are not restricted to being visual in nature, but can consist of more complex semantic and category-related information. Importantly, the experiments of this thesis demonstrate that attentional control is a highly flexible cognitive mechanism that can be rapidly altered on the basis of current goals, and can rapidly influence the processing of incoming visual information.
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Murase, Hiroshi, Ichiro Ide, Tomokazu Takahashi, Daisuke Deguchi, and Hiroyuki Uchiyama. "Removal of Moving Objects from a Street-View Image by Fusing Multiple Image Sequences." IEEE, 2010. http://hdl.handle.net/2237/14468.
38
Chiu, Wai-kei, and 趙偉奇. "Hollowing and reinforcing 3D CAD models and representing multiple material objects for rapid prototyping." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B29768470.
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Chavez, Garcia Ricardo Omar. "Multiple sensor fusion for detection, classification and tracking of moving objects in driving environments." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENM034/document.
Анотація:
Les systèmes avancés d'assistance au conducteur (ADAS) aident les conducteurs à effectuer des tâches de conduite complexes et à éviter ou atténuer les situations dangereuses. Le véhicule détecte le monde extérieur au moyen de capteurs, et ensuite construit et met à jour un modèle interne de la configuration de l'environnement. La perception de véhicule consiste à établir des relations spatiales et temporelles entre le véhicule et les obstacles statiques et mobiles dans l'environnement. Cette perception se compose de deux tâches principales : la localisation et cartographie simultanées (SLAM) traite de la modélisation de pièces statiques; et la détection et le suivi d'objets en mouvement (DATMO) est responsable de la modélisation des pièces mobiles dans l'environnement. Afin de réaliser un bon raisonnement et contrôle, le système doit modéliser correctement l'environnement. La détection précise et la classification des objets en mouvement est un aspect essentiel d'un système de suivi d'objets. Classification des objets en mouvement est nécessaire pour déterminer le comportement possible des objets entourant le véhicule, et il est généralement réalisée au niveau de suivi des objets. La connaissance de la classe d'objets en mouvement au niveau de la détection peut aider à améliorer leur suivi. La plupart des solutions de perception actuels considèrent informations de classification seulement comme information additional pour la sortie final de la perception. Aussi, la gestion de l'information incomplète est une exigence importante pour les systèmes de perception. Une information incomplète peut être originaire de raisons liées à la détection, tels que les problèmes d calibrage et les dysfonctionnements des capteurs; ou des perturbations de la scène, comme des occlusions, des problèmes de météo et objet déplacement. Les principales contributions de cette thèse se concentrent sur la scène DATMO. Précisément, nous pensons que l'inclusion de la classe de l'objet comme un élément clé de la représentation de l'objet et la gestion de l'incertitude de plusieurs capteurs de détections, peut améliorer les résultats de la tâche de perception. Par conséquent, nous abordons les problèmes de l'association de données, la fusion de capteurs, la classification et le suivi à différents niveaux au sein de la phase de DATMO. Même si nous nous concentrons sur un ensemble de trois capteurs principaux: radar, lidar, et la caméra, nous proposons une architecture modifiables pour inclure un autre type ou nombre de capteurs. Premièrement, nous définissons une représentation composite de l'objet pour inclure des informations de classe et de l'état d'objet deouis le début de la tâche de perception. Deuxièmement, nous proposons, mettre en œuvre, et comparons deux architectures de perception afin de résoudre le problème de DATMO selon le niveau où l'association des objets, la fusion et la classification des informations sont inclus et appliquées. Nos méthodes de fusion de données sont basées sur la théorie de l'evidence, qui est utilisé pour gérer et inclure l'incertitude de la détection du capteur et de la classification des objets. Troisièmement, nous proposons une approche d'association de données bassée en la théorie de l'evidence pour établir une relation entre deux liste des détections d'objets. Quatrièmement, nous intégrons nos approches de fusion dans le cadre d'une application véhicule en temps réel. Cette intégration a été réalisée dans un réelle démonstrateur de véhicule du projet European InteractIVe. Finalement, nous avons analysé et évalué expérimentalement les performances des méthodes proposées. Nous avons comparé notre fusion rapproche les uns contre les autres et contre une méthode state-of-the-art en utilisant des données réelles de scénarios de conduite différents. Ces comparaisons sont concentrés sur la détection, la classification et le suivi des différents objets en mouvement: piétons, vélos, voitures et camionsAdvanced driver assistance systems (ADAS) help drivers to perform complex driving tasks and to avoid or mitigate dangerous situations. The vehicle senses the external world using sensors and then builds and updates an internal model of the environment configuration. Vehicle perception consists of establishing the spatial and temporal relationships between the vehicle and the static and moving obstacles in the environment. Vehicle perception is composed of two main tasks: simultaneous localization and mapping (SLAM) deals with modelling static parts; and detection and tracking moving objects (DATMO) is responsible for modelling moving parts in the environment. In order to perform a good reasoning and control, the system has to correctly model the surrounding environment. The accurate detection and classification of moving objects is a critical aspect of a moving object tracking system. Therefore, many sensors are part of a common intelligent vehicle system. Classification of moving objects is needed to determine the possible behaviour of the objects surrounding the vehicle, and it is usually performed at tracking level. Knowledge about the class of moving objects at detection level can help improve their tracking. Most of the current perception solutions consider classification information only as aggregate information for the final perception output. Also, management of incomplete information is an important requirement for perception systems. Incomplete information can be originated from sensor-related reasons, such as calibration issues and hardware malfunctions; or from scene perturbations, like occlusions, weather issues and object shifting. It is important to manage these situations by taking them into account in the perception process. The main contributions in this dissertation focus on the DATMO stage of the perception problem. Precisely, we believe that including the object's class as a key element of the object's representation and managing the uncertainty from multiple sensors detections, we can improve the results of the perception task, i.e., a more reliable list of moving objects of interest represented by their dynamic state and appearance information. Therefore, we address the problems of sensor data association, and sensor fusion for object detection, classification, and tracking at different levels within the DATMO stage. Although we focus on a set of three main sensors: radar, lidar, and camera, we propose a modifiable architecture to include other type or number of sensors. First, we define a composite object representation to include class information as a part of the object state from early stages to the final output of the perception task. Second, we propose, implement, and compare two different perception architectures to solve the DATMO problem according to the level where object association, fusion, and classification information is included and performed. Our data fusion approaches are based on the evidential framework, which is used to manage and include the uncertainty from sensor detections and object classifications. Third, we propose an evidential data association approach to establish a relationship between two sources of evidence from object detections. We observe how the class information improves the final result of the DATMO component. Fourth, we integrate the proposed fusion approaches as a part of a real-time vehicle application. This integration has been performed in a real vehicle demonstrator from the interactIVe European project. Finally, we analysed and experimentally evaluated the performance of the proposed methods. We compared our evidential fusion approaches against each other and against a state-of-the-art method using real data from different driving scenarios. These comparisons focused on the detection, classification and tracking of different moving objects: pedestrian, bike, car and truck
40
Jeong, Ja-Yeon Pizer Stephen M. "Estimation of probability distribution on multiple anatomical objects and evaluation of statistical shape models." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2275.
Анотація:
Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.Title from electronic title page (viewed Jun. 26, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Computer Science." Discipline: Computer Science; Department/School: Computer Science.
41
Chiu, Wai-kei. "Hollowing and reinforcing 3D CAD models and representing multiple material objects for rapid prototyping /." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22050498.
42
Molnár, Zoltán. "Multiple mechanisms in the establishment of thalamocortical innervation." Thesis, University of Oxford, 1994. http://ora.ox.ac.uk/objects/uuid:4e802e0b-6a11-4d92-9820-5697b70292c1.
43
Groom, Laura R. "Synthesis and reactions of titanium-nitrogen multiple bonds." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:17286f91-a1d9-48dc-baf3-02fbbe30a314.
Анотація:
This Thesis reports the synthesis and reactions of new hydrazide, alkoxyimide and benzimidamide complexes (L)Ti=NX (X = NAr2, NOtBu or C(Ar)NOtBu; L = dianionic supporting ligand or ligand set). The work is supported by DFT calculations which are used to rationalise the reaction outcomes observed and, in one case, the bonding in alkoxyimide complexes. Chapter One provides a background to hydrazide complexes, starting with their relevance to nitrogen fixation. In addition, Group 4 imide, alkylidene hydrazide and alkoxyimide complexes are also reviewed. The Chapter focuses in particular on the synthesis, structure, and stoichiometric and catalytic reactions of these complexes with unsaturated substrates. Chapter Two describes the development of the virtually unexplored 1,2-diamination reaction. The substrate scope and isolation of the vinylamine products are discussed. The protonation of the vinylimide complex Ti(N2NMe){NC(Ph)C(Me)NPh2}(py) and the overall diamination reaction itself is then explored through an in-depth experimental and computational study. Chapter Three details the synthesis of cyclopentadienyl-amidinate supported alkoxyimide complexes. The first detailed reactivity study, supported by structural and computational studies, of any alkoxyimide complex is reported. Novel reactivity at Ti=Nα and, in one instance, Nα–Oβ reductive bond cleavage is observed. Chapter Four describes the reactivity of the benzimidamide complex Cp*Ti{PhC(NiPr)2}{NC(ArF5)NOtBu} with a range of substrates including heterocumulenes, aldehydes, isonitriles and B(ArF5)3. Novel reactivity at Ti=Nα, and 3-component coupling is presented, and the experimental results supported by structural and computational studies. Chapter Five presents full experimental procedures and characterising data for the new complexes reported.
44
Erdmann, Michael, and Tomas Lozano-Perez. "On Multiple Moving Objects." 1986. http://hdl.handle.net/1721.1/5602.
Анотація:
This paper explores the motion planning problem for multiple moving objects. The approach taken consists of assigning priorities to the objects, then planning motions one object at a time. For each moving object, the planner constructs a configuration space-time that represents the time-varying constraints imposed on the moving object by the other moving and stationary objects. The planner represents this space-time approximately, using two-dimensional slices. The space-time is then searched for a collision-free path. The paper demonstrates this approach in two domains. One domain consists of translating planar objects; the other domain consists of two-link planar articulated arms.
45
"Priming Creativity Using Multiple Artistic Objects." Master's thesis, 2013. http://hdl.handle.net/2286/R.I.20845.
Анотація:
abstract: As the desire for innovation increases, individuals and companies seek reliable ways to encourage their creative side. There are many office superstitions about how creativity works, but few are based on psychological science and even fewer have been tested empirically. One of the most prevalent superstitions is the use of objects to inspire creativity or even make a creative room. It is important to test this kind of notion so workplaces can find reliable ways to be innovative, but also because psychology lacks a breadth of literature on how environmental cues interact with people to shape their mental state. This experiment seeks to examine those gaps and fill in the next steps needed for examining at how multiple objects prime creativity. Participants completed two creativity tasks: one for idea generation and one that relies on insight problem solving, the Remote Association Task. There were four priming conditions that relied on objects: a zero object condition, a four neutral (office) objects condition, a single artistic object condition, and finally a four artistic objects condition. There were no differences found between groups for either type of task or in mood or artistic experience. The number of years a participant spent in the United States, however, did correlate with mood, idea generation scores, and insight problem scores. This potentially demonstrates that performance on idea generation and insight tasks rely on the tasks created and culture.Dissertation/Thesis
M.S. Applied Psychology 2013
46
Liu, Yu-Cheng, and 劉育誠. "Visual Attention Based Multiple Objects Discovery." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/57086558138536061762.
Анотація:
碩士國立清華大學
電機工程學系
97
In this thesis, we present a visual attention based probabilistic framework for the video objects discovery scheme. The framework consists of three models: the appearance model use probabilistic representation to describe the consistency of object across frame; the spatial model represents the objects’ geometric structure; the motion model establishes the temporal association of objects. In order to complete the video multiple objects discovery, we use Perceptual Quality Significance Map (PQSM) for the visual attention model. The visual attention regions from PQSM can be regarded as objects. We also use those regions to describe the appearance, size, and initial location of objects. Finally, the probabilistic parameters are obtained by Expectation-Maximization (EM) algorithm. Since the scene of video may switch between different shots, we use these probabilistic parameters to indicate which frame has the discovered objects and measure the similarity of objects in different shots. The mainly different from object tracking is object discovery can discover the object across different shots. We show the results that can be performed very well for video multiple objects discovery. And the attention regions from PQSMs are used to generate the object information for the motion model. Since the motion model is used to establish the data association, the temporal association of attention regions from PQSMs can be established by this proposed model.
47
LIU, ZHENG-XIONG, and 劉政雄. "3-D objects recognition from multiple views." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/80596039402397040579.
48
Chia-Jung, Chang. "Tracking Multiple Moving Objects Using Level Set Method." 2001. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0009-0112200611321218.
49
Naeem, Nomair A. "Verification of temporal properties involving multiple interacting objects." Thesis, 2013. http://hdl.handle.net/10012/8013.
Анотація:
Defects that arise due to violating a prescribed order for executing statements or executing a disallowed sequence of statements can be hard to detect since the sequence is often spread over multiple functions and source code files. In this dissertation, we develop a verification tool which uses a sound and precise static analysis to verify temporal specifications that can involve multiple objects.
Statically analyzing properties that involve multiple objects requires two separate abstractions; one that abstracts the objects in the program and the second which abstracts the state of a group of objects. We present two such abstractions. Objects are abstracted using a storeless heap abstraction. This provides flow-sensitive tracking of individual objects along control flow paths and precise may-alias information. The state abstraction leverages the object abstraction to abstract the state of a group of related objects.
We use the IFDS algorithm to implement an analysis that computes the object and state abstractions. Since the original IFDS algorithm is not directly suitable for domains involving objects and pointers, we present four extensions to the original IFDS algorithm. We also present results of an empirical study to measure the precision of the analysis.
The performance of the analysis is improved through the use of two types of method summaries. Callee summaries guarantee that using the summary instead of flow-sensitive analysis of the callee does not degrade the precision of the abstraction at the callsite for the callee. For further performance gains, caller summaries that make conservative assumptions for aliasing between parameters of a function call are used. We present results from empirically evaluating the use of these summaries for the object analysis.
Finally, to make the analysis practical for use in the development life cycle, we present a verification tool to
configure the analysis and visualize the results. The tool provides a number of configuration options to run the analysis.
The analysis results are presented in a list displaying statements flagged as possible violations of a property and, for each violation, the sequence of events (statements) that lead to this violation.
50
Chang, Chia-Jung, and 張家榮. "Tracking Multiple Moving Objects Using Level Set Method." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/37745314916322758147.
Анотація:
博士元智大學
電機工程研究所
89
This paper presents a novel approach to track multiple moving objects using the Level-set method. First, in order to overcome the problem of camera motion, a block matching method is used to estimate the information of camera motion for background compensation. Then, the difference image is obtained by subtracting two adjacent frames. With the difference image, different moving objects can be detected using the Level-set method. Furthermore, a Gaussian object model is used to remove object shadows. Finally, through connected component analysis, an object-relation table is created to track all the detected objects efficiently. Experimental results show that the proposed method is much robust and powerful than other traditional methods.