Dissertations / Theses on the topic 'Vision model'
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Gomes, Herman M. "Model learning in iconic vision." Thesis, University of Edinburgh, 2002. http://hdl.handle.net/1842/323.
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Generally, object recognition research falls into three main categories: (a) geometric, symbolic or structure based recognition, which is usually associated with CAD-based vision and 3-D object recognition; (b) property, vector or feature based recognition, involving techniques that vary from specific feature vectors, multiple filtering to global descriptors for shape, texture and colour; and (c) iconic or image based recognition, which either complies with the traditional sensor architecture of an uniform array of sampling units, or uses alternative representations. An example is the log-polar image, which is inspired by the human visual system and besides requiring less pixels, has some useful mathematical properties. The context of this thesis is a combination of the above categories in the sense that it investigates the area of iconic based recognition using image features and geometric relationships. It expands an existing vision system that operates by fixating at interesting regions in a scene, extracting a number of raw primal sketch features from a log-polar image and matching new regions to previously seen ones. Primal sketch features like edges, bars, blobs and ends are believed to take part of early visual processes in humans providing cues for an attention mechanism and more compact representations for the image data. In an earlier work, logic operators were defined to extract these features, but the results were not satisfactory. This thesis initially investigates the question of whether or not primal sketch features could be learned from log-polar images, and gives an affirmative answer. The feature extraction process was implemented using a neural network which learns examples of features in a window of receptive fields of the log-polar image. An architecture designed to encode the feature’s class, position, orientation and contrast has been proposed and tested. Success depended on the incorporation of a function that normalises the feature’s orientation and a PCA pre-processing module to produce better separation in the feature space. A strategy that combines synthetic and real features is used for the learning process. This thesis also provides an answer to the important, but so far not well explored, question of how to learn relationships from sets of iconic object models obtained from a set of images. An iconic model is defined as a set of regions, or object instances, that are similar to each other, organised into a geometric model specified by the relative scales, orientations, positions and similarity scores for each pair of image regions. Similarities are measured with a cross-correlation metric and relative scales and orientations are obtained from the best matched translational variants generated in the log-polar space. A solution to the structure learning problem is presented in terms of a graph based representation and algorithm. Vertices represent instances of an image neighbourhood found in the scenes. An edge in the graph represents a relationship between two neighbourhoods. Intra and inter model relationships are inferred by means of the cliques found in the graph, which leads to rigid geometric models inferred from the image evidence.
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Dickinson, John William. "Image structure and model-based vision." Thesis, University of Oxford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.292532.
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Brown, Gary. "An object oriented model of machine vision." Thesis, Kingston University, 1997. http://eprints.kingston.ac.uk/20614/.
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In this thesis an object oriented model is proposed that satisfies the requirements for a generic, customisable, reusable and flexible machine vision framework. These requirements are identified as being: ease of customisation for a particular application domain; independence from image definition; independence from shape representation scheme; ability to add new domain specific shape descriptors; independence from implemented machine vision algorithms; and the ability to maximise reuse of the generic framework. The thesis begins with a review of key machine vision functions and traditional architectures. In particular, machine vision architectures predicated on a process oriented framework are examined in detail and evaluated against the criteria stated above. An object oriented model is developed within the thesis, identifying the key classes underlying the machine vision domain. The responsibilities of these classes, and the relationships between them, are analysed in the context of high level machine vision tasks, for example object recognition. This object oriented approach is then contrasted with the more traditional process oriented approach. The object oriented model and framework is subsequently evaluated through a customisation, to illustrate an example machine vision application, namely Surface Mounted Electronic Assembly inspection. The object oriented model is also evaluated in the context of two functional machine vision applications described in literature. The model developed in this thesis incorporates the fundamental object oriented concepts of abstraction, encapsulation, inheritance and polymorphism. The results show that an object oriented approach does achieve the requirements for a generic, customisable, reusable and flexible machine vision framework.
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Vasilaki, Eleni. "A biologically inspired dynamic model for vision." Thesis, University of Sussex, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.288864.
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Broun, A. "Autonomous model building using vision and manipulation." Thesis, University of the West of England, Bristol, 2016. http://eprints.uwe.ac.uk/25851/.
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It is often the case that robotic systems require models, in order to successfully control themselves, and to interact with the world. Models take many forms and include kinematic models to plan motions, dynamics models to understand the interaction of forces, and models of 3D geometry to check for collisions, to name but a few. Traditionally, models are provided to the robotic system by the designers that build the system. However, for long-term autonomy it becomes important for the robot to be able to build and maintain models of itself, and of objects it might encounter. In this thesis, the argument for enabling robotic systems to autonomously build models is advanced and explored. The main contribution of this research is to show how a layered approach can be taken to building models. Thus a robot, starting with a limited amount of information, can autonomously build a number of models, including a kinematic model, which describes the robot’s body, and allows it to plan and perform future movements. Key to the incremental, autonomous approach is the use of exploratory actions. These are actions that the robot can perform in order to gain some more information, either about itself, or about an object with which it is interacting. A method is then presented whereby a robot, after being powered on, can home its joints using just vision, i.e. traditional methods such as absolute encoders, or limit switches are not required. The ability to interact with objects in order to extract information is one of the main advantages that a robotic system has over a purely passive system, when attempting to learn about or build models of objects. In light of this, the next contribution of this research is to look beyond the robot’s body and to present methods with which a robot can autonomously build models of objects in the world around it. The first class of objects examined are flat pack cardboard boxes, a class of articulated objects with a number of interesting properties. It is shown how exploratory actions can be used to build a model of a flat pack cardboard box and to locate any hinges the box may have. Specifically, it is shown how when interacting with an object, a robot can combine haptic feedback from force sensors, with visual feedback from a camera to get more information from an object than would be possible using just a single sensor modality. The final contribution of this research is to present a series of exploratory actions for a robotic text reading system that allow text to be found and read from an object. The text reading system highlights how models of objects can take many forms, from a representation of their physical extents, to the text that is written on them.
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Hnatow, Justin Michael. "A theoretical eye model for uncalibrated real-time eye gaze estimation /." Online version of thesis, 2006. http://hdl.handle.net/1850/2606.
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Shao, Yuan. "A Bayesian reasoning framework for model-driven vision." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284789.
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Du, Li. "The viewpoint consistency constraint in model-based vision." Thesis, University of Reading, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317162.
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Becker, Shawn C. (Shawn Carter). "Vision-assisted modeling for model-based video representations." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/29123.
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Li, Min. "Novel frameworks for deformable model and nonrigid motion analysis." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.87Mb, 145 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/3181869.
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Sandlin, Melissa C. "Model-based vision-guided automated cutting of natural products." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/17931.
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Bodington, R. "Truth maintenance and constraint satisfaction in model-based vision." Thesis, University of Reading, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.277136.
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Ruggles, Samantha Anna. "Quantifying Computer Vision Model Quality Using Various Processing Techniques." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/6066.
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Recently, the use of unmanned aerial vehicles (UAVs) has increased in popularity across several industries. Most notable, however, is the impact that this technology has had in research at academic institutions worldwide. As the technology for UAVs has improved, with that comes easier to operate, more accessible equipment. UAVs have been used in various types of applications and are quickly becoming a preferred method of studying and analyzing a site. Currently, the most common use of a UAV is to monitor a location of interest to a researcher that is difficult to gain access to otherwise. The UAV can be altered to meet the needs of any given project and this versatility has contributed to their popularity. Often, they are equipped with a type of remote sensor that can gather information in the form of images, sounds, heat, or light. Once data has been gathered from a site, it is processed and modified, allowing it to be studied and analyzed. A process known as Structure from Motion (SfM) creates a 3D digital terrain model from camera images captured through the use of a UAV. SfM is a common method of processing the vast amount of images that are taken at a site and the 3D model that it creates is a helpful resource for analysis. These digital models, while useful, are oftentimes created at an unknown accuracy. This research presents a comparative study of the accuracies obtained when different parameters are applied during the SfM process. The results present a comparison of the time required to process a particular model and the accuracy that the model had. Depending on the application and type of project, a desired level of accuracy can be obtained in the presented amount of time. This particular study used a landslide as the site of interest and captured the imagery using a helicopter UAV.
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Azarbayejani, Ali J. "Model-based vision navigation for a free-flying robot." Thesis, Massachusetts Institute of Technology, 1991. http://hdl.handle.net/1721.1/43240.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics and Dept. of Electrical Engineering and Computer Science, 1991.Includes bibliographical references (p. 125-127).
by Ali J. Azarbayejani.
M.S.
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Takalo, J. (Jouni). "Towards natural insect vision research." Doctoral thesis, University of Oulu, 2013. http://urn.fi/urn:isbn:9789526203249.
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Visual world is naturally correlated both spatially and temporally. The correlations are used in vision to enhance performance of neurons. For gaining maximal neural performance of the visual neurons, the experiments, from stimulus to the analysis, should be designed to take advantage of the correlations. In this thesis methods for generating and analyzing natural stimuli were examined by using computations and algorithms.
For analyzing responses to natural stimuli in visual neurons, a method with only a few assumptions was developed for estimating information rate in long responses. The novel method gave a good agreement with Shannon information rate with linear system and Gaussian input but was able to handle also nonlinear processing and non-Gaussian data.
Secondly, a computer controlled 3D virtual environment with a spherical screen was developed, with a large visual field. The image of the world was projected to the screen with a DLP projector, giving good enough temporal performance for insect vision research. A track-ball was used in closed loop experiments.
Thirdly, properties of single photon (“bump”) information transfer at various light levels were investigated in cockroach photoreceptor with a coarse computational model. At dim light (< 10 ph/s), where single bump responses were visible, shot noise was dominant. At higher light levels latency distribution of the bump decreased the information rate, but amplitude distribution of bump did not have an effect.
Fourthly, the contribution of K⁺ channels to information rate and energy consumption was investigated by creating a database of computation models with varying channel compositions. The information rate has a maximum as a function of mean conductance, which was a sum of the average K⁺ conductance and the leak conductance. This maximum was fine-tuned by the K⁺ channel composition, which had high so-called novel contribution and relatively low amount of other conductances.
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Burger, Alwyn Johannes. "Occupancy grid mapping using stereo vision." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/96925.
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Thesis (MEng)--Stellenbosch University, 2015.ENGLISH ABSTRACT: This thesis investigates the use of stereo vision sensors for dense autonomous mapping. It characterises and analyses the errors made during the stereo matching process so measurements can be correctly integrated into a 3D grid-based map. Maps are required for navigation and obstacle avoidance on autonomous vehicles in complex, unknown environments. The safety of the vehicle as well as the public depends on an accurate mapping of the environment of the vehicle, which can be problematic when inaccurate sensors such as stereo vision are used. Stereo vision sensors are relatively cheap and convenient, however, and a system that can create reliable maps using them would be beneficial. A literature review suggests that occupancy grid mapping poses an appropriate solution, offering dense maps that can be extended with additional measurements incrementally. It forms a grid representation of the environment by dividing it into cells, and assigns a probability to each cell of being occupied. These probabilities are updated with measurements using a sensor model that relates measurements to occupancy probabilities. Numerous forms of these sensor models exist, but none of them appear to be based on meaningful assumptions and sound statistical principles. Furthermore, they all seem to be limited by an assumption of unimodal, zero-mean Gaussian measurement noise. Therefore, we derive a principled inverse sensor model (PRISM) based on physically meaningful assumptions. This model is capable of approximating any realistic measurement error distribution using a Gaussian mixture model (GMM). Training a GMM requires a characterisation of the measurement errors, which are related to the environment as well as which stereo matching technique is used. Therefore, a method for fitting a GMM to the error distribution of a sensor using measurements and ground truth is presented. Since we may consider the derived principled inverse sensor model to be theoretically correct under its assumptions, we use it to evaluate the approximations made by other models from the literature that are designed for execution speed. We show that at close range these models generally offer good approximations that worsen with an increase in measurement distance. We test our model by creating maps using synthetic and real world data. Comparing its results to those of sensor models from the literature suggests that our model calculates occupancy probabilities reliably. Since our model captures the limited measurement range of stereo vision, we conclude that more accurate sensors are required for mapping at greater distances.
AFRIKAANSE OPSOMMING: Hierdie tesis ondersoek die gebruik van stereovisie sensors vir digte outonome kartering. Dit karakteriseer en ontleed die foute wat gemaak word tydens die stereopassingsproses sodat metings korrek geïntegreer kan word in 'n 3D rooster-gebaseerde kaart. Sulke kaarte is nodig vir die navigasie en hindernisvermyding van outonome voertuie in komplekse en onbekende omgewings. Die veiligheid van die voertuig sowel as die publiek hang af van 'n akkurate kartering van die voertuig se omgewing, wat problematies kan wees wanneer onakkurate sensors soos stereovisie gebruik word. Hierdie sensors is egter relatief goedkoop en gerieflik, en daarom behoort 'n stelsel wat hulle dit gebruik om op 'n betroubare manier kaarte te skep baie voordelig te wees. 'n Literatuuroorsig dui daarop dat die besettingsroosteralgoritme 'n geskikte oplossing bied, aangesien dit digte kaarte skep wat met bykomende metings uitgebrei kan word. Hierdie algoritme skep 'n roostervoorstelling van die omgewing en ken 'n waarskynlikheid dat dit beset is aan elke sel in die voorstelling toe. Hierdie waarskynlikhede word deur nuwe metings opgedateer deur gebruik te maak van 'n sensormodel wat beskryf hoe metings verband hou met besettingswaarskynlikhede. Menigde a eidings bestaan vir hierdie sensormodelle, maar dit blyk dat geen van die modelle gebaseer is op betekenisvolle aannames en statistiese beginsels nie. Verder lyk dit asof elkeen beperk word deur 'n aanname van enkelmodale, nul-gemiddelde Gaussiese metingsgeraas. Ons lei 'n beginselfundeerde omgekeerde sensormodel af wat gebaseer is op fisies betekenisvolle aannames. Hierdie model is in staat om enige realistiese foutverspreiding te weerspieël deur die gebruik van 'n Gaussiese mengselmodel (GMM). Dit vereis 'n karakterisering van 'n stereovisie sensor se metingsfoute, wat afhang van die omgewing sowel as watter stereopassingstegniek gebruik is. Daarom stel ons 'n metode voor wat die foutverspreiding van die sensor met behulp van 'n GMM modelleer deur gebruik te maak van metings en absolute verwysings. Die afgeleide ge inverteerde sensormodel is teoreties korrek en kan gevolglik gebruik word om modelle uit die literatuur wat vir uitvoerspoed ontwerp is te evalueer. Ons wys dat op kort afstande die modelle oor die algemeen goeie benaderings bied wat versleg soos die metingsafstand toeneem. Ons toets ons nuwe model deur kaarte te skep met gesimuleerde data, sintetiese data, en werklike data. Vergelykings tussen hierdie resultate en dié van sensormodelle uit die literatuur dui daarop dat ons model besettingswaarskynlikhede betroubaar bereken. Aangesien ons model die beperkte metingsafstand van stereovisie vasvang, lei ons af dat meer akkurate sensors benodig word vir kartering oor groter afstande.
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Tsang, Kong Chau. "Preference for phase-based disparity in a neuromorphic implementation of the binocular energy model /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20TSANG.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 64-66). Also available in electronic version. Access restricted to campus users.
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Ungruh, Joachim. "A neurally based vision model for line extraction and attention." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/8303.
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Al-Takrouri, Saleh Othman Saleh Electrical Engineering & Telecommunications Faculty of Engineering UNSW. "Robust state estimation and model validation techniques in computer vision." Publisher:University of New South Wales. Electrical Engineering & Telecommunications, 2008. http://handle.unsw.edu.au/1959.4/41002.
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The main objective of this thesis is to apply ideas and techniques from modern control theory, especially from robust state estimation and model validation, to various important problems in computer vision. Robust model validation is used in texture recognition where new approaches for classifying texture samples and segmenting textured images are developed. Also, a new model validation approach to motion primitive recognition is demonstrated by considering the motion segmentation problem for a mobile wheeled robot. A new approach to image inpainting based on robust state estimation is proposed where the implementation presented here concerns with recovering corrupted frames in video sequences. Another application addressed in this thesis based on robust state estimation is video-based tracking. A new tracking system is proposed to follow connected regions in video frames representing the objects in consideration. The system accommodates tracking multiple objects and is designed to be robust towards occlusions. To demonstrate the performance of the proposed solutions, examples are provided where the developed methods are applied to various gray-scale images, colored images, gray-scale videos and colored videos. In addition, a new algorithm is introduced for motion estimation via inverse polynomial interpolation. Motion estimation plays a primary role within the video-based tracking system proposed in this thesis. The proposed motion estimation algorithm is also applied to medical image sequences. Motion estimation results presented in this thesis include pairs of images from a echocardiography video and a robot-assisted surgery video.
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Miller, J. "Cognitive processes described in terms of Marr's model of vision." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374233.
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Lloyd, Charles J. C. "A human spatial-chromatic vision model for evaluating electronic displays." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/29310.
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This dissertation examines those attributes of full-color display systems (particularly color matrix displays) which degrade image quality. Based on this analysis, it is suggested that a comprehensive metric should measure image quality in terms of transmitted signal and noise modulation, both achromatic and chromatic. Moreover, it is suggested that these signal and noise measurements be weighted in terms of human spatial-chromatic visual characteristics.
A review of extant image quality metrics reveals several limitations of these metrics which make them unsuitable for the evaluation of color matrix displays. These limitations include the inability to account for chromatic modulation transfer and chromatic noise as well as the general inability to account for spatial and grey-scale sampling.
This work describes a new methodology for assessing image quality that can be applied to full-color as well as monochromatic, and sampled as well as continuous, display systems. Unlike most display quality metrics, the proposed methodology is not based on the tools of linear systems analysis. Rather, it is based on more veridical models of the human visual system (HVS), including multi-channel models of spatial vision, the zone theory of color vision, physiological models of retinal processes, and models of the optics of the eye.
A display evaluation system consisting of the HVS model used in conjunction with a display simulator is described. The HVS model employs nine image processing stages to account for nonlinear retinal processes, opponent color encoding, and multiple spatial frequency channels. A detailed procedure for using the HVS model to evaluate display systems is provided.
The validity of the HVS model was tested by conducting contrast detection, discrimination, and magnitude estimation experiments on the model. The results of these experiments correspond closely with published human performance data The utility of the display evaluation system was assessed by making image quality predictions for the display systems used in three image quality studies. Image quality predictions using the proposed system correlate strongly with ratings of image quality provided by human subjects. Results of these validation studies indicate that the proposed method of display evaluation is viable and warrants further development.Ph. D.
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Krampoťák, Štefan. "Model dopravních situací." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219706.
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This master thesis deals with analyze of camera system in real traffic, using these system and realization of traffic situation model. Result of this work is fully functional model of traffic situation, which shows the capability of these camera systems in real traffic. It consists of two basic parts, the first is physical model of traffic with semaphore and second part is control program with algorithm for detection of traffic offences. The system contains speed measurement and red light violation. Model has capable of control the speed of cars, control semaphores and configure cameras.
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Liang, Chen. "3D model reconstruction from silhouettes." Click to view the E-thesis via HKUTO, 2008. http://sunzi.lib.hku.hk/hkuto/record/b40203311.
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Liang, Chen, and 梁晨. "3D model reconstruction from silhouettes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2008. http://hub.hku.hk/bib/B40203311.
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Liu, Yan. "Negative feedback control of the visual system and systematic colors vision model /." Online version of thesis, 1991. http://hdl.handle.net/1850/11211.
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Li, Shuda. "Combining silhouette and shading cues for model reconstruction." Click to view the E-thesis via HKUTO, 2007. http://sunzi.lib.hku.hk/hkuto/record/B39634255.
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Rosin, P. "Model driven image understanding : A frame-based approach." Thesis, City University London, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382816.
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Ceino, Tantaleán Ricardo, Flores Phiera Antonia Escalante, Garragate Carlos Antonio Mendoza, and Bardales Raúl Arturo Zúñiga. "Diagnóstico del modelo de gestión en una empresa de transporte de carga pesada por carretera." Master's thesis, Universidad Peruana de Ciencias Aplicadas (UPC), 2020. http://hdl.handle.net/10757/653230.
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Con el presente trabajo, se ha elaborado un “DIAGNÓSTICO DEL MODELO DE GESTIÓN EN UNA EMPRESA DE TRANSPORTE DE CARGA PESADA POR CARRETERA”; al respecto, hemos tenido limitantes como el acceso a determinada información de la compañía debido a sus políticas de seguridad así como la limitación de traslado y comunicación generada por la pandemia COVID-19 que ha afectado sustancialmente a todo el país; con todo ello, hemos culminado con éxito, logrando el objetivo de tener un diagnóstico de calidad que permita mejorar la gestión de la compañía quedando solo en su decisión el implementarla.
Luego del análisis realizado, proponemos implementar un modelo de gestión EFQM que es acorde a la realidad actual de la compañía. De que asegurarán obtener resultados rentables y sostenibles para la organización. Asimismo, con el compromiso de los colaboradores, se logrará una cultura organizacional orientada a una visión estratégica que contribuya al desarrollo de la empresa y de la sociedad.This work is about a "DIAGNOSIS OF THE MANAGEMENT MODEL IN A HEAVY LOAD TRANSPORTATION COMPANY". It has been prepared although, we have had limitations such as access to certain company information due to its security policies as well as the limitation communication visits due to the COVID-19 pandemic that has substantially affected the entire country. Despite of all this, we have successfully achieved the objective of having a quality diagnosis that could allow to make some improvements on the management of the company. The implementation of the improvements is now up to the company. After the analysis carried out, our proposal is to implement an EFQM management model that is consistent with the current reality of the company. Some improvements have been proposed in order to ensure profitable and sustainable results for the organization. Likewise, with the commitment of all employees, an organizational culture oriented towards a strategic vision that contributes to the development of the company and society will be achieved.
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Jackson, Jeremy D. "Layered Deformotion with Radiance: A Model for Appearance, Segmentation, Registration, and Tracking." Diss., Available online, Georgia Institute of Technology, 2007, 2007. http://etd.gatech.edu/theses/available/etd-07092007-104249/.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2008.Vela, Patricio, Committee Member ; Tannenbaum, Allen, Committee Member ; Yezzi, Anthony, Committee Chair ; Turk, Greg, Committee Member ; Lanterman, Aaron, Committee Member.
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Sahiner, Ali Vahit. "A computation model for parallelism : self-adapting parallel servers." Thesis, University of Westminster, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305872.
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黃業新 and Yip-san Wong. "A two-level model-based object recognition technique." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1995. http://hub.hku.hk/bib/B31213807.
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Wong, Yip-san. "A two-level model-based object recognition technique /." Hong Kong : University of Hong Kong, 1995. http://sunzi.lib.hku.hk/hkuto/record.jsp?B14705552.
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Stevens, Jean-Luc Richard. "Spatiotemporal properties of evoked neural response in the primary visual cortex." Thesis, University of Edinburgh, 2018. http://hdl.handle.net/1842/31330.
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Understanding how neurons in the primary visual cortex (V1) of primates respond to visual patterns has been a major focus of research in neuroscience for many decades. Numerous different experimental techniques have been used to provide data about how the spatiotemporal patterns of light projected from the visual environment onto the retina relate to the spatiotemporal patterns of neural activity evoked in the visual cortex, across disparate spatial and temporal scales. However, despite the variety of data sources available (or perhaps because of it), there is still no unified explanation for how the circuitry in the eye, the subcortical visual pathways, and the visual cortex responds to these patterns. This thesis outlines a research project to build computational models of V1 that incorporate observations and constraints from an unprecedented range of experimental data sources, reconciling each data source with the others into a consistent proposal for the underlying circuitry and computational mechanisms. The final mechanistic model is the first one shown to be compatible with measurements of: (1) temporal firing-rate patterns in single neurons over tens of milliseconds obtained using single-unit electrophysiology, (2) spatiotemporal patterns in membrane voltages in cortical tissues spanning several square millimeters over similar time scales, obtained using voltage-sensitive-dye imaging, and (3) spatial patterns in neural activity over several square millimeters of cortex, measured over the course of weeks of early development using optical imaging of intrinsic signals. Reconciling this data was not trivial, in part because single-unit studies suggested short, transient neural responses, while population measurements suggested gradual, sustained responses. The fundamental principles of the resulting models are (a) that the spatial and temporal patterns of neural responses are determined not only by the particular properties of a visual stimulus and the internal response properties of individual neurons, but by the collective dynamics of an entire network of interconnected neurons, (b) that these dynamics account both for the fast time course of neural responses to individual stimuli, and the gradual emergence of structure in this network via activity-dependent Hebbian modifications of synaptic connections over days, and (c) the differences between single-unit and population measurements are primarily due to extensive and wide-ranging forms of diversity in neural responses, which become crucial when trying to estimate population responses out of a series of individual measurements. The final model is the first to include all the types of diversity necessary to show how realistic single-unit responses can add up to the very different population-level evoked responses measured using voltage-sensitive-dye imaging over large cortical areas. Additional contributions from this thesis include (1) a comprehensive solution for doing exploratory yet reproducible computational research, implemented as a set of open-source tools, (2) a general-purpose metric for evaluating the biological realism of model orientation maps, and (3) a demonstration that the previous developmental model that formed the basis of the models in this thesis is the only developmental model so far that produces realistic orientation maps. These analytical results, computational models, and research tools together provide a systematic approach for understanding neural responses to visual stimuli across time scales from milliseconds to weeks and spatial scales from microns to centimeters.
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Kamenetsky, Dmitry, and dkamen@rsise anu edu au. "Ising Graphical Model." The Australian National University. ANU College of Engineering and Computer Science, 2010. http://thesis.anu.edu.au./public/adt-ANU20100727.221031.
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The Ising model is an important model in statistical physics, with over 10,000 papers published on the topic. This model assumes binary variables and only local pairwise interactions between neighbouring nodes. Inference for the general Ising model is NP-hard; this includes tasks such as calculating the partition function, finding a lowest-energy (ground) state and computing marginal probabilities. Past approaches have proceeded by working with classes of tractable Ising models, such as Ising models defined on a planar graph. For such models, the partition function and ground state can be computed exactly in polynomial time by establishing a correspondence with perfect matchings in a related graph.
In this thesis we continue this line of research. In particular we simplify previous inference algorithms for the planar Ising model. The key to our construction is the complementary correspondence between graph cuts of the model graph and perfect matchings of its expanded dual. We show that our exact algorithms are effective and efficient on a number of real-world machine learning problems. We also investigate heuristic methods for approximating ground states of non-planar Ising models. We show that in this setting our approximative algorithms are superior than current state-of-the-art methods.
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Devillard, François. "Vision du robot mobile Mithra." Grenoble INPG, 1993. http://www.theses.fr/1993INPG0112.
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Nous proposons un ensemble de vision stereoscopique embarque, destine a la navigation d'un robot mobile en site industriel. En robotique mobile, les systemes de vision sont soumis a de severes contraintes de fonctionnement (traitement en temps reel, volume, consommation. . . ). Pour une modelisation 3D de l'environnement, le systeme de vision doit utiliser des indices visuels permettant un codage compact, precis et robuste de la scene observee. Afin de repondre au mieux aux contraintes de vitesse, nous nous sommes attaches a extraire, des images, les informations les plus significatives d'un point de vue topologique. Dans le cas de missions en sites industriels, l'ensemble des projets presente des geometries orthogonales telles que les intersections de cloisons, les portes, les fenetres, le mobilier. . . La detection des geometries proches de la verticale permet une definition suffisante de l'environnement tout en reduisant la redondance des informations visuelles dans des proportions satisfaisantes. Les indices utilises sont des segments de droite verticaux extraits de deux images stereoscopiques. Nous proposons des solutions algorithmiques pour la detection de contours et l'approximation polygonale adaptees a une implementation temps reel. Ensuite, nous presentons le systeme de vision realise. L'ensemble est constitue de 2 cartes VME. La premiere carte est un operateur cable systolique implementant l'acquisition d'images et la detection de contours. La seconde est concue a partir d'un processeur de traitement de signal et realise l'approximation polygonale. La conception et la realisation de ce systeme de vision a ete realisee dans le cadre du projet de robotique mobile EUREKA EU 110 (Mithra)
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Komodakis, Nikos. "Graphical Model Inference and Learning for Visual Computing." Habilitation à diriger des recherches, Université Paris-Est, 2013. http://tel.archives-ouvertes.fr/tel-00866078.
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Computational vision and image analysis is a multidisciplinary scientific field that aims to make computers "see" in a way that is comparable to human perception. It is currently one of the most challenging research areas in artificial intelligence. In this regard, the extraction of information from the vast amount of visual data that are available today as well as the exploitation of the resulting information space becomes one of the greatest challenges in our days. To address such a challenge, this thesis describes a very general computational framework that can be used for performing efficient inference and learning for visual perception based on very rich and powerful models.
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Li, Shuda, and 李書達. "Combining silhouette and shading cues for model reconstruction." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B39634255.
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De, Franchis Carlo. "Earth Observation and Stereo Vision." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLN002/document.
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Cette thèse étudie les problèmes posés par l’estimation automatique de modèles numériques d’élévation de la surface terrestre à partir de photographies prises par des satellites. Ce travail a bénéficié d’une collaboration avec le CNES (Centre National d’Etudes Spatiales) sur le développement d’outils de vision stéréoscopique pour Pléiades, le premier satellite d’observation de la Terre capable de produire des paires ou triplets d’images quasi-simultanées. Le premier chapitre de la thèse décrit un modèle simplifié de caméra pushbroom destiné aux satellites d’observation de la Terre, et aborde le problème de la correction des données de calibration en faisant intervenir des mesures externes. Ce chapitre propose un nouvel algorithme pour affiner les paramètres d’orientation du satellite à partir d’un jeu de points de contrôle. Il est utilisable pour tous les satellites munis de caméras pushbroom. Dans le but d’appliquer aux images satellitaires les nombreux algorithmes de mise en correspondance stéréoscopique développés en traitement d’images et en vision par ordinateur, le deuxième chapitre explore l’adaptation de la théorie de la rectification épipolaire aux images prises par des caméras pushbroom. La rectification épipolaire est utilisée habituellement pour réduire la complexité du problème de mise en correspondance stéréoscopique, et permet d’appliquer les algorithmes les plus récents à des images satellitaires. Le chapitre suivant étudie les effets des erreurs de calibration géométrique sur la rectification et propose une méthode pour éliminer leur impact sur la mise en correspondance. Le quatrième chapitre décrit et analyse en détails une implémentation de l’algorithme Semi-Global Matching (SGM), classé actuellement parmi les meilleurs algorithmes de mise en correspondance stéréoscopique. En se fondant sur une réinterprétation récente de SGM, ce chapitre en propose une variante qui permet de réduire d’un facteur cinq son écart en énergie par rapport aux algorithmes de référence pour la minimisation de champs aléatoires de Markov. En assemblant les blocs algorithmiques décrits dans les chapitres précédents, le cinquième chapitre décrit S2P, une chaîne stéréoscopique complète qui produit des modèles numériques d’élévation à partir d’images satellitaires. Un modèle d’évolution de paysage est présenté dans le sixième chapitre comme exemple d’application. Le modèle est utilisé pour simuler numériquement la structure fine du réseau hydrographique sur des modèles numériques d’élévation obtenus à partir d’images prises par Pléiades. Le code source de la chaîne S2P2 est distribué en tant que logiciel open source. Afin d’assurer la reproductibilité des résultats obtenus, les algorithmes implémentés dans S2P sont en cours de publication dans le journal IPOL, accompagnés de descriptions et d’analyses détaillées, de codes sources documentés et de démonstrateurs en ligneThis thesis deals with the problem of computing accurate digital elevationmodels of the Earth's surface from optical images taken by pushbroomobservation satellites. It takes advantage of the collaboration of thedefendant with CNES (the French Space Agency) on the development ofstereo vision tools for Pléiades, the first Earth observation satelliteproducing quasi simultaneous stereo pairs or triplets with small baseline.The first chapter describes a simple pushbroom camera model for observationsatellites orbiting around the Earth and addresses the correction of theacquisition geometry by involving extrinsic information. This chapter proposesa new algorithm to refine the orientation parameters from a set of groundcontrol points, applicable to all pushbroom satellites.With the goal of testing for satellite imaging the thriving exploration ofstereo matching by the computer vision community, the second chapter exploresthe adaptation of the theory of epipolar resampling to pushbroom images.Epipolar resampling is traditionally used in stereo to reduce the matchingcomputational cost, and permits to test for satellite imaging the mostcompetitive computer vision algorithms. The third chapter discusses the effectsof geometric calibration inaccuracies and proposes a method to cancel itsimpact on stereo matching.The fourth chapter analyzes and describes a detailed implementation of theSemi-Global Matching (SGM) algorithm, which is currently among the top-rankedstereo vision algorithms. Based on a recently proposed interpretation of SGM asa min-sum Belief Propagation algorithm, a variant is proposed that allows toreduce by a factor five the energy gap of SGM with respect to referencealgorithms for Markov Random Fields with truncated smoothness terms.By wrapping together the algorithmic blocks described in the previous chapters,the fifth chapter describes S2P, a complete stereo pipeline for producingdigital elevation models from satellite images. As an application, a landscapeevolution model is presented in the sixth chapter. The model is used tosimulate numerically the fine structure of the river networks on digitalelevation models obtained from Pléiades Earth observation images.The source code of the S2P stereo pipeline is distributed as open source. Toensure reproducibility, the algorithms implemented in each step of the S2Ppipeline are submitted to the IPOL journal, with detailed descriptions of thealgorithms, documented source codes and online demonstrations for each block ofthe pipeline
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Lau, Hoi Ying. "Neural inspired color constancy model based on double opponent neurons /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20LAU.
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許建平 and Kin-ping Hui. "Computer texture boundary detection based on texton model and neural positive feedback." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B42574298.
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Hui, Kin-ping. "Computer texture boundary detection based on texton model and neural positive feedback." [Hong Kong] : The University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record/B42574298.
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Ziv, Ronen. "Moving Beyond the RNR and GLM Models: Building a New Vision for Offender Rehabilitation." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479819588267395.
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Halverson, Timothy E. "An "active vision" computational model of visual search for human-computer interaction /." Connect to title online (Scholars' Bank) Connect to title online (ProQuest), 2008. http://hdl.handle.net/1794/9174.
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Thesis (Ph. D.)--University of Oregon, 2008.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 185-191). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
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Vaiapury, Karthikeyan. "Model based 3D vision synthesis and analysis for production audit of installations." Thesis, Queen Mary, University of London, 2013. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8721.
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One of the challenging problems in the aerospace industry is to design an automated 3D vision system that can sense the installation components in an assembly environment and check certain safety constraints are duly respected. This thesis describes a concept application to aid a safety engineer to perform an audit of a production aircraft against safety driven installation requirements such as segregation, proximity, orientation and trajectory. The capability is achieved using the following steps. The initial step is to perform image capture of a product and measurement of distance between datum points within the product with/without reference to a planar surface. This provides the safety engineer a means to perform measurements on a set of captured images of the equipment they are interested in. The next step is to reconstruct the digital model of fabricated product by using multiple captured images to reposition parts according to the actual model. Then, the projection onto the 3D digital reconstruction of the safety related installation constraints, respecting the original intent of the constraints that are defined in the digital mock up is done. The differences between the 3D reconstruction of the actual product and the design time digital mockup of the product are identified. Finally, the differences/non conformances that have a relevance to safety driven installation requirements with reference to the original safety requirement intent are identified. The above steps together give the safety engineer the ability to overlay a digital reconstruction that should be as true to the fabricated product as possible so that they can see how the product conforms or doesn't conform to the safety driven installation requirements. The work has produced a concept demonstrator that will be further developed in future work to address accuracy, work flow and process efficiency. A new depth based segmentation technique GrabcutD which is an improvement to existing Grabcut, a graph cut based segmentation method is proposed. Conventional Grabcut relies only on color information to achieve segmentation. However, in stereo or multiview analysis, there is additional information that could be also used to improve segmentation. Clearly, depth based approaches bear the potential discriminative power of ascertaining whether the object is nearer of farer. We show the usefulness of the approach when stereo information is available and evaluate it using standard datasets against state of the art result.
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Halverson, Timothy E. 1971. "An "active vision" computational model of visual search for human-computer interaction." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/9174.
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xx, 191 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.Visual search is an important part of human-computer interaction (HCI). The visual search processes that people use have a substantial effect on the time expended and likelihood of finding the information they seek. This dissertation investigates visual search through experiments and computational cognitive modeling. Computational cognitive modeling is a powerful methodology that uses computer simulation to capture, assert, record, and replay plausible sets of interactions among the many human processes at work during visual search. This dissertation aims to provide a cognitive model of visual search that can be utilized by predictive interface analysis tools and to do so in a manner consistent with a comprehensive theory of human visual processing, namely active vision. The model accounts for the four questions of active vision, the answers to which are important to both practitioners and researchers in HCI: What can be perceived in a fixation? When do the eyes move? Where do the eyes move? What information is integrated between eye movements? This dissertation presents a principled progression of the development of a computational model of active vision. Three experiments were conducted that investigate the effects of visual layout properties: density, color, and word meaning. The experimental results provide a better understanding of how these factors affect human- computer visual interaction. Three sets of data, two from the experiments reported here, were accurately modeled in the EPIC (Executive Process-Interactive Control) cognitive architecture. This work extends the practice of computational cognitive modeling by (a) informing the process of developing computational models through the use of eye movement data and (b) providing the first detailed instantiation of the theory of active vision in a computational framework. This instantiation allows us to better understand (a) the effects and interactions of visual search processes and (b) how these visual search processes can be used computationally to predict people's visual search behavior. This research ultimately benefits HCI by giving researchers and practitioners a better understanding of how users visually interact with computers and provides a foundation for tools to predict that interaction. This dissertation includes-both previously published and co-authored material.
Adviser: Anthony J. Hornof
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Thor, Nandan G. "Using Computer Vision to Build a Predictive Model of Fruit Shelf-life." DigitalCommons@CalPoly, 2017. https://digitalcommons.calpoly.edu/theses/1721.
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Computer vision is becoming a ubiquitous technology in many industries on account of its speed, accuracy, and long-term cost efficacy. The ability of a computer vision system to quickly and efficiently make quality decisions has made computer vision a popular technology on inspection lines. However, few companies in the agriculture industry use computer vision because of the non-uniformity of sellable produce. The small number of agriculture companies that do utilize computer vision use it to extract features for size sorting or for a binary grading system: if the piece of fruit has a certain color, certain shape, and certain size, then it passes and is sold. If any of the above criteria are not met, then the fruit is discarded. This is a highly wasteful and relatively subjective process.
This thesis proposes a process to undergo to use computer vision techniques to extract features of fruit and build a model to predict shelf-life based on the extracted features. Fundamentally, the existing agricultural processes that do use computer vision base their distribution decisions on current produce characteristics. The process proposed in this thesis uses current characteristics to predict future characteristics, which leads to more informed distribution decisions. By modeling future characteristics, the process proposed will allow fruit characterized as “unfit to sell” by existing standards to still be utilized (i.e. if the fruit is too ripe to ship across the country, it can still be sold locally) which decreases food waste and increases profit. The process described also removes the subjectivity present in current fruit grading systems. Further, better informed distribution decisions will save money in storage costs and excess inventory.
The proposed process consists of discrete steps to follow. The first step is to choose a fruit of interest to model. Then, the first of two experiments is performed. Sugar content of a large sample of fruit are destructively measured (using a refractometer) to correlate sugar content to a color range. This step is necessary to determine the end-point of data collection because stages of ripeness are fundamentally subjective. The literature is consulted to determine “ripe” sugar content of the fruit and the first experiment is undertaken to correlate a color range that corresponds to the “ripe” sugar content. This feature range serves as the end-point of the second experiment. The second experiment is large-scale data collection of the fruit of interest, with features being recorded every day, until the fruit reaches end-of-life as determined by the first experiment. Then, computer vision is used to perform feature extraction and features are recorded over each sample fruit’s lifetime. The recorded data is then analyzed with regression and other techniques to build a model of the fruit’s shelf-life. The model is finally validated. This thesis uses bananas as a proof of concept of the proposed process.
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Wang, Hanzi. "Robust statistics for computer vision : model fitting, image segmentation and visual motion analysis." Monash University, Dept. of Electrical and Computer Systems Engineering, 2004. http://arrow.monash.edu.au/hdl/1959.1/5345.
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Damweber, Michael Frank. "Model independent offset tracking with virtual feature points." Thesis, Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/17651.
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Harris, Daniel I. "A biologically inspired focus of attention model /." Online version of thesis, 2008. http://hdl.handle.net/1850/5712.
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Mainguy, Yves. "A robust variable order facet model for image data." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10222009-124949/.
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