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Ducrocq, Julien. "Vision catadioptrique pour favoriser la perception d'environnements hétérogènes". Electronic Thesis or Diss., Amiens, 2022. http://www.theses.fr/2022AMIE0067.
Pełny tekst źródłaThis thesis presents the conception methods of two catadioptric cameras capable of recording usable images of heterogeneous environments. These cameras belong to the adaptive vision field, which gathers the cameras of which the optics or sensor have heterogeneous properties which can vary across time. Adaptive cameras abilities include capturing heterogenous environments which physical or geometrical properties change across space. This thesis proposes a survey of the state of the art on adaptive cameras which are able to capture specific types of heterogenous environments. On the one hand, we consider the scenes characterized by a spatial variation of radiances, with a dynamic range around 120 decibels. These scenes put conventional cameras in difficulty, their images have some pixels saturated and others to dark, because of their low dynamic range. In both casses, these image regions does not carry any visual information about the scene, they are not usable. In order to capture the radiances corresponding to these bright and dark areas, the high dynamic range cameras (HDR) are used. Nonetheless, there is no available HDR panoramic camera yet. Therefore, the first contribution of this thesis is the conception of an HDR panoramic camera in order to improve robots navigation, with only visual perception, in outdoor scenes with various. Mounted on a mobile robot, this camera enlarges the convergence domain and the positioning accuracy of a robot by direct visual servoing, outdoors. On the other hand, we consider the scenes which have a non-uniform level of details across space : some scene elements carry more visual information than the others. To capture such heterogeneous environments, the second contribution of this thesis is an adaptive camera. This camera is based on a new deformable mirror of local curvatures allowing to enlarge or reduce the number of pixels occupied by scene regions in the image. This camera, nicknamed Visadapt, capture multi-résolution images which depend on scene content. From one scene to another, the shape of the mirror may be changed to optimise the resolution of the images captured to this new scene. The surface of the mirror is made of material both reflective and deformable, the mylar, and changes of shape thanks to a grid of linear actuators placed underneath. This mirror, plan as an initial state, is able to change shape to give to the scene regions captured by Visadapt the desired resolution in the image. The characteristics of Visadapt, particularly the dimensions, the materials of its different elements and the actuators pitch, have been defined thanks to a simulation study. A real prototype have been built to respect the parameters defined by the simulation. The experiments shown that this prototype is able to magnify up to four scene regions at once. This thesis ends with a conclusion presenting future works to upgrade the prototypes of the two cameras, in order to enhance their performances and the diversity of images they can capture. Furthermore, this conclusion proposes research tracks to improve even further these two cameras and even adaptive vision in general
Pace, Brian A. "Physiology, Photochemistry, and Fitness of Mexican Maize Landraces in the Field". The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1545421491370678.
Pełny tekst źródłaIversen, Katarina. "Virtuella vägmarkeringar för att påverka hastighetsval vid bilkörning : Effekt och upplevelse hos bilförare med respektive utan ADHD". Thesis, Linköpings universitet, Institutionen för datavetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166321.
Pełny tekst źródłaMateus, Forero Andrea D. "DESIGN IN ADAPTATION TO DROUGHTS AND HEAT WAVES CAUSED BY CLIMATECHANGE IN RICE FARMS IN LERIDA, TOLIMA, COLOMBIA". Miami University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=miami151213167340772.
Pełny tekst źródłaSchrinner, Martin. "Mean-field view on geodynamo models". Doctoral thesis, [S.l.] : [s.n.], 2005. http://webdoc.sub.gwdg.de/diss/2005/schrinner.
Pełny tekst źródłaHansen, Jeremy Roger. "Wide field of view satellite tracking". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape3/PQDD_0031/MQ65844.pdf.
Pełny tekst źródłaCao, Shaohong. "Large field of view electron ptychography". Thesis, University of Sheffield, 2017. http://etheses.whiterose.ac.uk/19405/.
Pełny tekst źródłaHansen, Jeremy Roger. "Wide field of view satellite tracking". Ottawa : National Library of Canada = Bibliothèque nationale du Canada, 2002. http://www.nlc-bnc.ca/obj/s4/f2/dsk1/tape3/PQDD%5F0031/MQ65844.pdf.
Pełny tekst źródłaTakami, Kuya. "Non-Field-of-View Acoustic Target Estimation". Diss., Virginia Tech, 2015. http://hdl.handle.net/10919/56892.
Pełny tekst źródłaPh. D.
Chen, Xin. "Analytical Path to Improved RF Field Homogeneity for High Field MRI". Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1237482374.
Pełny tekst źródłaSpinks, Katie Rose. ""Factors that influence successful field placements" student and field instructor perspectives /". Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1243955704.
Pełny tekst źródłaYahya, Farouk. "Approche couplée discrète - continue adaptative pour la mise en forme des métaux". Electronic Thesis or Diss., Valenciennes, Université Polytechnique Hauts-de-France, 2023. http://www.theses.fr/2023UPHF0042.
Pełny tekst źródłaThe development of forming processes generally involves numerical simulation, particularly using the Finite Element Method, to detect, among other things, potential risks of cracking and their propagation, both in the forged piece and in the tooling.The classical Finite Element Method, as well as specific variants applied to crack modeling, have limitations when it comes to simulating multi-cracking problems due to material, geometric, and contact nonlinearities. The very nature of a crack – a discontinuity – is in opposition to the framework of Continuum Mechanics. On the other hand, the Discrete Element Method distinguishes itself by its ability to effectively handle discontinuities. It is used to model granular or brittle cohesive materials. However, this approach also has limitations, especially regarding the consideration of material nonlinearities and computation times, which may require significant computing resources to simulate complex problems.The objective of this thesis work was to develop a dynamic remeshing method that allowed transitioning between the two methods to leverage the advantages of both approaches. This objective was be achieved in three steps.Firstly, a non-overlapping coupling method based on the Lagrange multiplier method was developed. This method aimed at ensuring the compatibility of velocities between the discrete elements and finite elements subdomains to facilitate the communication of physical quantities between the two subdomains.Secondly, it was necessary to ensure the continuity of physical quantities within the same zone during its remeshing. This step was achieved by using polynomial interpolation of displacements. This approach allowed determining the fields within the discrete elements when the transition between a finite element subdomain and a discrete element subdomain took place. Test cases were set up to validate these two approaches.Finally, a method was developed to automate the management of coupling and field transfer operations. This approach involved the use of a remeshing technique that automatically generated discrete subdomains from the geometry of the entire finite elements to be replaced.The dynamic remeshing method implemented in this thesis work was applied to a Kalthoff test case and validated by comparing the crack propagation angle with experiments from the literature
Xiao, Peng. "Optique adaptative et interférométrie spatialement incohérente plein champ pour l’imagerie de la rétine". Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLET015/document.
Pełny tekst źródłaThis thesis follows the study and development of an adaptive optics full-field optical coherence tomography (AO-FFOCT) system, aiming for high resolution en face human retinal imaging. During the quantification of the effects of geometrical aberrations on the FFOCT system performance, it is shown that, with spatially incoherent illumination, the lateral resolution of FFOCT is insensitive to aberrations, which only cause the FFOCT signal reduction. Since low order aberrations like myopia and astigmatism dominate in human eye, a non-conjugate AO configuration by using transmissive wavefront corrector is suggested and applied for low order aberrations correction to simplify the AO-FFOCT system. Wavefront corrections are done with a wavefront sensorless method by using FFOCT signal level as the metric. Experiments with scattering samples and artificial eye model are conducted to demonstrate the feasibility of the customized AO-FFOCT system for aberration correction. In order to resolve the eye motion effects and employ real-time matching of the optical path lengths of the two interferometric arms in FFOCT, a system combination of traditional spectral-domain OCT (SDOCT) with FFOCT is adopted. With this combined system, high resolution FFOCT cellular retinal imaging is achieved in human eye in vivo for the first time
Ozkalayci, Burak Oguz. "Multi-view Video Coding Via Dense Depth Field". Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607517/index.pdf.
Pełny tekst źródłaHough, Petrina. "The useful field of view, driving, and dementia". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp01/MQ40011.pdf.
Pełny tekst źródłaKatkam, Rajender. "Dual field of view optical system for colonoscope". Thesis, The University of Arizona, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=1564291.
Pełny tekst źródłaThe present dual field of view flexible colonoscope can provide both forward view and radial or backward view of the colon to improve detection of cancerous polyps. The colonoscope has its own illumination that illuminates the parts of the colon viewed by imaging optics. The optical system, limited only by the diffraction effects at the exit pupil over the entire visible spectrum, can provide high resolution and is suitable for color imaging. The flexible colonoscope has an on-board sensor at the proximal end of the colonoscope to improve resolution. The proximal end of colonoscope measures only 8 mm in diameter and 20 mm in length. The present colonoscope has the potential to be scaled down to as small as 6 mm inner diameter from the present 8 mm.
Patel, Kruti D. "Neuropsychological Factors Associated with Useful Field of View". Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1395411154.
Pełny tekst źródłaYang, Fan S. M. Massachusetts Institute of Technology. "Achromatic and wide field-of-view metalens design". Thesis, Massachusetts Institute of Technology, 2021. https://hdl.handle.net/1721.1/130677.
Pełny tekst źródłaCataloged from the official PDF of thesis.
Includes bibliographical references (pages 47-50).
Achromatic and wide field-of-view (WFOV) optical functionalities are desired for various imaging applications. Conventional methods use complicated design approaches or assemble multiple optical components to form achromatic and WFOV lenses. They are bulky and have limited focusing quality. Here a novel metalens design is presented which shows extraordinary achromatic and WFOV focusing quality simultaneously. The metalens is composed of all-dielectric meta-atoms selected from a large meta-atoms library with diverse dispersion behavior. The metalens and an aperture are integrated on opposite sides of the substrate to separate areas with different angle-of- incidents (AOIs). A theoretical analysis and a direct search algorithm are combined to obtain optimum phase profile of metalens. This design concept is generic and can be applied to lenses with different parameters to meet the demands of various applications.
by Fan Yang.
S.M.
S.M. Massachusetts Institute of Technology, Department of Materials Science and Engineering
Sharma, Arvindh R. "Liquid Jet in Oscillating Crossflow: Characterization of Near-Field and Far-Field Spray Behavior". University of Cincinnati / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1439281517.
Pełny tekst źródłaCassel, Adrienne M. "Field Guide to the Heart". University of Cincinnati / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1307320455.
Pełny tekst źródłaRapin, Kathryn. "Do laboratory syndromes predict field behavior? Comparison of laboratory based syndromes and field based measurements". Bowling Green State University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1459776389.
Pełny tekst źródłaLjung, Kenth. "Effects of Field-of-View in First-Person Video Games : A Study on Camera Field-of-View in Relation to Game Design". Thesis, Uppsala universitet, Institutionen för speldesign, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-254330.
Pełny tekst źródłaHart, David Marvin. "Light-Field Style Transfer". BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7763.
Pełny tekst źródłaGrönqvist, Helena. "Vision Enhancement Systems : The Importance of Field of View". Thesis, Linköping University, Department of Computer and Information Science, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1370.
Pełny tekst źródłaThe purpose of the project, which led to this thesis, was to investigate the possible effects different horizontal Fields of View (FoV) have on driving performance when driving at night with a Vision Enhancement System (VES). The FoV chosen to be examined were 12 degree and 24 degree FoV, both displayed on a screen with the horizontal size of 12 degree FoV. This meant that the different conditions of FoV also had different display ratios 1:1 and 1:2. No effort was made to separate these parameters.
A simulator study was performed at the simulator at IKP, Linköping University. Sixteen participants in a within-group design participated in the study. The participants drove two road sections; one with a 12 degree FoV and the other with a 24 degree FoV. During each section four scenarios were presented in which the participants passed one of three types of objects; a moose, a deer or a man. In each section, two of the objects stood right next to the road and two were standing seventeen meters to the right of the road. As the drivers approached the objects standing seventeen meters to the right of the road, the objects moved out of the VES when the vehicle was 200 meters in front of the object with a 12 degree FoV. The objects could be seen with the naked eye when the vehicle was 100 meters in front of the object. When the drivers approached the objects with a 24degree FoV the objects moved out of the VES display when it was possible to see them unaided.
Results show that a 24 degree FoV displayed with a 1:2 ratio gives the drivers improved anticipatory control, compared to a 12 degree FoV displayed with a 1:1 ratio. The participants with a broader FoV were able to make informed decisions whereas with a narrow FoV some participants started to reaccelerate when they could not see an object. Results also show that any difference in recognition distance that may exist between a 12 degree and a 24 degree camera angle displayed in a 12 degree FoV display do not seem to have any adverse effect on the quality of driving.
Edwards, Jerri. "The Useful Field of View of Reading Disabled Children". TopSCHOLAR®, 1995. http://digitalcommons.wku.edu/theses/908.
Pełny tekst źródłaKoopman, Marjolein. "Nanoscale cell membrane organization a near-field optical view /". Enschede : University of Twente [Host], 2006. http://doc.utwente.nl/55930.
Pełny tekst źródłaFahmi, Kamal Hanna. "Participatory action research (PAR) : a view from the field". Thesis, McGill University, 2004. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84506.
Pełny tekst źródłaThe thesis draws on a participatory action research (PAR) methodology spanning eight years of fieldwork with street kids in Cairo, which eclectically combined street ethnography, street work and action science. I critically review the historical development of these methodologies, and I argue for a conception of PAR as an open-ended process of action and reflective participatory research incorporated into everyday activities and work with excluded, marginalized and oppressed groups such as street kids. As such, I pay special attention to the ethical dilemmas that arise in day-to-day PAR practice.
Prinsloo, David Schalk Van der Merwe. "Multi-mode antennas for hemispherical field-of-view coverage". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97008.
Pełny tekst źródłaENGLISH ABSTRACT: This dissertation proposes a multi-mode antenna element excited through a multiconductor feed. It is shown that each of the orthogonal transverse electromagnetic modes supported by the antenna feed results in a unique radiated far-field pattern that collectively allow for nearhemispherical field-of-view coverage. Three multi-mode antenna designs are presented: a dual-mode antenna, integrating a single linearly polarised dipole antenna with a co-located monopole, as well as two quad-mode antenna designs integrating two dual-polarised dipole elements with a co-located monopole element. The dual-mode antenna is excited through a balanced transmission line feed supporting both differential- and common-mode signals that, respectively, result in typical dipole-over-ground and monopole radiated far-field patterns. The quad-mode antennas are each fed through a quadraxial transmission line allowing for excitation through four orthogonal transverse electromagnetic port modes. To characterise the multi-mode response of the multi-mode antennas, generalised transformations are derived by which the multi-mode S-parameters and radiated far-fields can be calculated from the S-parameters and far-fields corresponding to single-ended excitations. These transformations are implemented to validate the response of a dual-mode and quad-mode antenna design through measurements. An equivalent network representation for active multi-mode antennas is presented, including generalised transformations relating the multi-mode signal and noise response of the low-noise amplifiers to the two-port S-parameters and noise parameters of the low-noise amplifiers. Through the use of classical beamforming algorithms, the performance of an active dual-mode and quadmode antenna is presented. In the case of the active dual-mode antenna, it is shown that through the added use of common-mode signals, a variation in sensitivity of less than 50% is achieved in the E-plane. Similarly, the additional excitation modes supported by the active quad-mode antenna is shown to result in a significant improvement in the polarimetric capabilities over the field-of-view coverage.
AFRIKAANSE OPSOMMING: Hierdie proefskrif stel ’n multimodale antenna element voor wat deur ’n multi-geleier transmissielyn gevoer word. Dit word gewys dat elk van die ortogonale transversale elektromagnetiese opwekkingsmodusse wat deur die antenna voer ondersteun word, ’n unieke vêrveld stralingspatroon skep, wat gesamentlik lei tot ’n hemisferiese gesigsveld. Drie multimodale antenna ontwerpe word voorgestel: ’n dubbelmodale antenna, waarin ’n enkel lineêrgepolariseerde dipool antenna en monopool mede-geleë word, asook twee viermodale antenna ontwerpe waarin twee dubbelgepolariseerde dipool elemente geïntegreer word met medegeleë monopool antenna elemente. Die dubbelmodale antenna word gevoer deur ’n gebalanseerde transmissielyn wat beide differensiële- en gemene-modus seine ondersteun, waar elk onderskeidelik dipool-oor-aardvlak en monopool stralingspatrone voortbring. Die viermodale antennas word elk gevoer deur vier-as transmissielyne wat vier ortogonale transversale elektromagnetiese opwekkingsmodusse ondersteun. Om die multimodale gedrag van die drie multimodale antennas te karakteriseer, word veralgemeende transformasies afgelei waardeur die multimodale strooiingsparameters asook die vêrveld stralingspatrone vanaf enkelpoort strooiingsparameters en vêrvelde bereken word. Hierdie transformasies word toegepas om die gedrag van ’n dubbel- en viermodale antenna ontwerp te karakteriseer deur metings. Ekwivalente netwerkvoorstellings vir aktiewe multimodale antennas word voorgestel, insluitend veralgemeende transformasies om die multimodale sein asook ruis gedrag van die lae-ruis versterkers betreklik te maak tot die tweepoort strooiingsparameters en ruisparameters van die laeruis versterkers. Deur gebruik te maak van klasieke bundelvormingsalgoritmes, word die gedrag van aktiewe dubbelmodale en viermodale antennas voorgestel. Vir die aktiewe dubbelmodale antenna word daar aangedui dat die gesamentlike gebruik van differensiële- en gemene-modus seine, ’n variasie in sensitiwiteit onder 50% tot gevolg het in die E-vlak. Soortgelyk word daar aangedui dat die addisionele opwekkingsmodusse wat deur die aktiewe viermodale antenna ondersteun word, tot ’n beduidende verbetering in die polarisasievermoë oor die gesigsveld lei.
Odom, Garret, i Garret Odom. "Diffusers in Coherently Illuminated, Wide Field of View Applications". Thesis, The University of Arizona, 2016. http://hdl.handle.net/10150/620709.
Pełny tekst źródłaMazin, Samuel R. "A Wide field-of-view inverse geometry CT system /". May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Pełny tekst źródłaHsu, Fang-Chi. "Electric field effect in "metallic" polymers". Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1127229727.
Pełny tekst źródłaTitle from first page of PDF file. Document formatted into pages; contains xxi, 177 p.; also includes graphics (some col.). Includes bibliographical references (p. 167-177). Available online via OhioLINK's ETD Center
Zhang, Cheng. "Far field ultrasonic welding of thermoplastics". Connect to resource, 1988. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1156875186.
Pełny tekst źródłaEswaran, Raman V. "Near field ultrasonic welding of thermoplastics". Connect to resource, 1988. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1157565798.
Pełny tekst źródłaFletcher, Kerra Rose. "Low field modulation of complex species". Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1197912416.
Pełny tekst źródłaDURHAM, PHILIP R. "Force Field Development for Calbindin D9k". University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218547540.
Pełny tekst źródłaChrisman, James Atticus. "Marsh's Field: A Novella and Introduction". Ohio University Honors Tutorial College / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ouhonors1429799538.
Pełny tekst źródłaWesolowski, Sarah. "Bayesian Methods for Effective Field Theories". The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1500037172071861.
Pełny tekst źródłaBrucker, Margaret. "The Binocular Visual Field in Glaucoma". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1523998138093264.
Pełny tekst źródłaKhakshoor, Morteza. "Like the Beasts of the Field". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1524072853367268.
Pełny tekst źródłaLiu, Shiyi. "Understanding Doped Organic Field-Effect Transistors". Kent State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=kent1574127009556301.
Pełny tekst źródłaAleman-Nieto, Alberto E. "Commande adaptative vectorielle d'un moteur asynchrone en utilisant un processeur de signal numérique". Université Joseph Fourier (Grenoble ; 1971-2015), 1996. http://www.theses.fr/1996GRE10141.
Pełny tekst źródłaGoldberg, Benjamin M. "Picosecond Electric Field CARS; A Diagnostic Technique to Measure the Electric Field Development within Nanosecond Repetitively Pulsed Plasmas". The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354303147.
Pełny tekst źródłaEspe-Sherwindt, Marilyn. "The Individualized Family Service Plan (IFSP) in the field of early intervention: how level is the playing field? /". The Ohio State University, 1996. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487931993468819.
Pełny tekst źródłaCompaleo, Jacob D. "Impact of Near-field-to-far-field Transformation on SAR Images Formed in an Indoor Non-anechoic Environment". Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1533206365760924.
Pełny tekst źródłaJackson, Lauren M. "The Effects of Decreased Uncertainty and Telescopic Versus Full Field Training on The Useful Field of View". TopSCHOLAR®, 1990. http://digitalcommons.wku.edu/theses/1698.
Pełny tekst źródłaDai, Zhenwen, i 戴振文. "A Markov random field approach for multi-view normal integration". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2009. http://hub.hku.hk/bib/B4308588X.
Pełny tekst źródłaVan, der Westhuizen Christo Carel. "Efficient registration of limited field of view ocular fundus imagery". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85633.
Pełny tekst źródłaENGLISH ABSTRACT: Diabetic- and hypertensive retinopathy are two common causes of blindness that can be prevented by managing the underlying conditions. Patients suffering from these conditions are encouraged to undergo regular examinations to monitor the retina for signs of deterioration. For these routine examinations an ophthalmoscope is used. An ophthalmoscope is a relatively inexpensive device that allows an examiner to directly observe the ocular fundus (the interior back wall of the eye that contains the retina). These devices are analog and do not allow the capture of digital imagery. Fundus cameras, on the other hand, are larger devices that o er high quality digital images. They do, however, come at an increased cost and are not practical for use in the eld. In this thesis the design and implementation of a system that digitises imagery from an ophthalmoscope is discussed. The main focus is the development of software algorithms to increase the quality of the images to yield results of a quality closer to that of a fundus camera. The aim is not to match the capabilities of a fundus camera, but rather to o er a cost-e ective alternative that delivers su cient quality for use in conducting routine monitoring of the aforementioned conditions. For the digitisation the camera of a mobile phone is proposed. The camera is attached to an ophthalmoscope to record a video of an examination. Software algorithms are then developed to parse the video frames and combine those that are of better quality. For the parsing a method of rapidly selecting valid frames based on colour thresholding and spatial ltering techniques are developed. Registration is the process of determining how the selected frames t together. Spatial cross-correlation is used to register the frames. Only translational transformations are assumed between frames and the designed algorithms focuses on estimating this relative translation in a large set of frames. Methods of optimising these operations are also developed. For the combination of the frames, averaging is used to form a composite image. The results obtained are in the form of enhanced grayscale images of the fundus. These images do not match those captured with fundus cameras in terms of quality, but do show a signi cant increase when compared to the individual frames that they consists of. Collectively a set of video frames can cover a larger region of the fundus than what they do individually. By combining these frames an e ective increase in the eld of view is obtained. Due to low light exposure, the individual frames also contain signi cant noise. In the results the noise is reduced through the averaging of several frames that overlap at the same location.
AFRIKAANSE OPSOMMING: Diabetiese- en hipertensiewe retinopatie is twee algemene oorsake van blindheid wat deur middel van die behandeling van die onderliggende oorsake voorkom kan word. Pasiënte met hierdie toestande word aangemoedig om gereeld ondersoeke te ondergaan om die toestand van die retina te monitor. 'n Oftalmoskoop word gebruik vir hierdie roetine ondersoeke. 'n Oftalmoskoop is 'n relatiewe goedkoop, analoë toestel wat 'n praktisyn toelaat om die agterste interne wand van die oog the ondersoek waar die retina geleë is. Fundus kameras, aan die ander kant, is groter toestelle wat digitale beelde van 'n hoë gehalte kan neem. Dit kos egter aansienlik meer en is dus nie geskik vir gebruik in die veld nie. In hierdie tesis word die ontwerp en implementering van 'n stelsel wat beelde digitaliseer vanaf 'n oftalmoskoop ondersoek. Die fokus is op die ontwikkeling van sagteware algoritmes om die gehalte van die beelde te verhoog. Die doel is nie om die vermoëns van 'n fundus kamera te ewenaar nie, maar eerder om 'n koste-e ektiewe alternatief te lewer wat voldoende is vir gebruik in die veld tydens die roetine monitering van die bogenoemde toestande. 'n Selfoonkamera word vir die digitaliserings proses voorgestel. Die kamera word aan 'n oftalmoskoop geheg om 'n video van 'n ondersoek af te neem. Sagteware algoritmes word dan ontwikkel om die videos te ontleed en om videogrepe van goeie kwaliteit te selekteer en te kombineer. Vir die aanvanklike ontleding van die videos word kleurband drempel tegnieke voorgestel. Registrasie is die proses waarin die gekose rame bymekaar gepas word. Direkte kruiskorrelasie tegnieke word gebruik om die videogrepe te registreer. Daar word aanvaar dat die videogrepe slegs translasie tussen hulle het en die voorgestelde registrasie metodes fokus op die beraming van die relatiewe translasie van 'n groot versameling videogrepe. Vir die kombinering van die grepe, word 'n gemiddeld gebruik om 'n saamgestelde beeld te vorm. Die resultate wat verkry word, word in die vorm van verbeterde gryskleur beelde van die fundus ten toon gestel. Hierdie beelde is nie gelykstaande aan die kwaliteit van beelde wat deur 'n fundus kamera geneem is nie. Hulle toon wel 'n beduidende verbetering teenoor individuele videogrepe. Deur dat 'n groot versameling videogrepe wat gesamentlik 'n groter area van die fundus dek gekombineer word, word 'n e ektiewe verhoging van data in die area van die saamgestelde beeld verkry. As gevolg van lae lig blootstelling van die individuele grepe bevat hul beduidende ruis. In die saamgestelde beelde is die ruis aansienlik minder as gevolg van 'n groter hoeveelheid data wat gekombineer is om sodoende die ruis uit te sluit.
Dai, Zhenwen. "A Markov random field approach for multi-view normal integration". Click to view the E-thesis via HKUTO, 2009. http://sunzi.lib.hku.hk/hkuto/record/B4308588X.
Pełny tekst źródłaModoran, Georgia C. "Intense field electron excitation in transparent materials". Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1133273960.
Pełny tekst źródłaMarinov, Toma M. "Field Emission and Scattering From Conducting Nanofibers". University of Akron / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=akron1217614626.
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