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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Shape recovery from reflection.

January 1996 (has links)
by Yingli Tian. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 202-222). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Physics-Based Shape Recovery Techniques --- p.3 / Chapter 1.2 --- Proposed Approaches to Shape Recovery in this Thesis --- p.9 / Chapter 1.3 --- Thesis Outline --- p.13 / Chapter 2 --- Camera Model in Color Vision --- p.15 / Chapter 2.1 --- Introduction --- p.15 / Chapter 2.2 --- Spectral Linearization --- p.17 / Chapter 2.3 --- Image Balancing --- p.21 / Chapter 2.4 --- Spectral Sensitivity --- p.24 / Chapter 2.5 --- Color Clipping and Blooming --- p.24 / Chapter 3 --- Extended Light Source Models --- p.27 / Chapter 3.1 --- Introduction --- p.27 / Chapter 3.2 --- A Spherical Light Model in 2D Coordinate System --- p.30 / Chapter 3.2.1 --- Basic Photometric Function for Hybrid Surfaces under a Point Light Source --- p.32 / Chapter 3.2.2 --- Photometric Function for Hybrid Surfaces under the Spher- ical Light Source --- p.34 / Chapter 3.3 --- A Spherical Light Model in 3D Coordinate System --- p.36 / Chapter 3.3.1 --- Radiance of the Spherical Light Source --- p.36 / Chapter 3.3.2 --- Surface Brightness Illuminated by One Point of the Spher- ical Light Source --- p.38 / Chapter 3.3.3 --- Surface Brightness Illuminated by the Spherical Light Source --- p.39 / Chapter 3.3.4 --- Rotating the Source-Object Coordinate to the Camera- Object Coordinate --- p.41 / Chapter 3.3.5 --- Surface Reflection Model --- p.44 / Chapter 3.4 --- Rectangular Light Model in 3D Coordinate System --- p.45 / Chapter 3.4.1 --- Radiance of a Rectangular Light Source --- p.45 / Chapter 3.4.2 --- Surface Brightness Illuminated by One Point of the Rect- angular Light Source --- p.47 / Chapter 3.4.3 --- Surface Brightness Illuminated by a Rectangular Light Source --- p.47 / Chapter 4 --- Shape Recovery from Specular Reflection --- p.54 / Chapter 4.1 --- Introduction --- p.54 / Chapter 4.2 --- Theory of the First Method --- p.57 / Chapter 4.2.1 --- Torrance-Sparrow Reflectance Model --- p.57 / Chapter 4.2.2 --- Relationship Between Surface Shapes from Different Images --- p.60 / Chapter 4.3 --- Theory of the Second Method --- p.65 / Chapter 4.3.1 --- Getting the Depth of a Reference Point --- p.65 / Chapter 4.3.2 --- Recovering the Depth and Normal of a Specular Point Near the Reference Point --- p.67 / Chapter 4.3.3 --- Recovering Local Shape of the Object by Specular Reflection --- p.69 / Chapter 4.4 --- Experimental Results and Discussions --- p.71 / Chapter 4.4.1 --- Experimental System and Results of the First Method --- p.71 / Chapter 4.4.2 --- Experimental System and Results of the Second Method --- p.76 / Chapter 5 --- Shape Recovery from One Sequence of Color Images --- p.81 / Chapter 5.1 --- Introduction --- p.81 / Chapter 5.2 --- Temporal-color Space Analysis of Reflection --- p.84 / Chapter 5.3 --- Estimation of Illuminant Color Ks --- p.88 / Chapter 5.4 --- Estimation of the Color Vector of the Body-reflection Component Kl --- p.89 / Chapter 5.5 --- Separating Specular and Body Reflection Components and Re- covering Surface Shape and Reflectance --- p.91 / Chapter 5.6 --- Experiment Results and Discussions --- p.92 / Chapter 5.6.1 --- Results with Interreflection --- p.93 / Chapter 5.6.2 --- Results Without Interreflection --- p.93 / Chapter 5.6.3 --- Simulation Results --- p.95 / Chapter 5.7 --- Analysis of Various Factors on the Accuracy --- p.96 / Chapter 5.7.1 --- Effects of Number of Samples --- p.96 / Chapter 5.7.2 --- Effects of Noise --- p.99 / Chapter 5.7.3 --- Effects of Object Size --- p.99 / Chapter 5.7.4 --- Camera Optical Axis Not in Light Source Plane --- p.102 / Chapter 5.7.5 --- Camera Optical Axis Not Passing Through Object Center --- p.105 / Chapter 6 --- Shape Recovery from Two Sequences of Images --- p.107 / Chapter 6.1 --- Introduction --- p.107 / Chapter 6.2 --- Method for 3D Shape Recovery from Two Sequences of Images --- p.109 / Chapter 6.3 --- Genetics-Based Method --- p.111 / Chapter 6.4 --- Experimental Results and Discussions --- p.115 / Chapter 6.4.1 --- Simulation Results --- p.115 / Chapter 6.4.2 --- Real Experimental Results --- p.118 / Chapter 7 --- Shape from Shading for Non-Lambertian Surfaces --- p.120 / Chapter 7.1 --- Introduction --- p.120 / Chapter 7.2 --- Reflectance Map for Non-Lambertian Color Surfaces --- p.123 / Chapter 7.3 --- Recovering Non-Lambertian Surface Shape from One Color Image --- p.127 / Chapter 7.3.1 --- Segmenting Hybrid Areas from Diffuse Areas Using Hue Information --- p.127 / Chapter 7.3.2 --- Calculating Intensities of Specular and Diffuse Compo- nents on Hybrid Areas --- p.128 / Chapter 7.3.3 --- Recovering Shape from Shading --- p.129 / Chapter 7.4 --- Experimental Results and Discussions --- p.131 / Chapter 7.4.1 --- Simulation Results --- p.131 / Chapter 7.4.2 --- Real Experimental Results --- p.136 / Chapter 8 --- Shape from Shading under Multiple Extended Light Sources --- p.142 / Chapter 8.1 --- Introduction --- p.142 / Chapter 8.2 --- Reflectance Map for Lambertian Surface Under Multiple Rectan- gular Light Sources --- p.144 / Chapter 8.3 --- Recovering Surface Shape Under Multiple Rectangular Light Sources --- p.148 / Chapter 8.4 --- Experimental Results and Discussions --- p.150 / Chapter 8.4.1 --- Synthetic Image Results --- p.150 / Chapter 8.4.2 --- Real Image Results --- p.152 / Chapter 9 --- Shape from Shading in Unknown Environments by Neural Net- works --- p.167 / Chapter 9.1 --- Introduction --- p.167 / Chapter 9.2 --- Shape Estimation --- p.169 / Chapter 9.2.1 --- Shape Recovery Problem under Multiple Rectangular Ex- tended Light Sources --- p.169 / Chapter 9.2.2 --- Forward Network Representation of Surface Normals --- p.170 / Chapter 9.2.3 --- Shape Estimation --- p.174 / Chapter 9.3 --- Application of the Neural Network in Shape Recovery --- p.174 / Chapter 9.3.1 --- Structure of the Neural Network --- p.174 / Chapter 9.3.2 --- Normalization of the Input and Output Patterns --- p.175 / Chapter 9.4 --- Experimental Results and Discussions --- p.178 / Chapter 9.4.1 --- Results for Lambertian Surface under One Rectangular Light --- p.178 / Chapter 9.4.2 --- Results for Lambertian Surface under Four Rectangular Light Sources --- p.180 / Chapter 9.4.3 --- Results for Hybrid Surface under One Rectangular Light Sources --- p.190 / Chapter 9.4.4 --- Discussions --- p.190 / Chapter 10 --- Summary and Conclusions --- p.191 / Chapter 10.1 --- Summary Results and Contributions --- p.192 / Chapter 10.2 --- Directions of Future Research --- p.199 / Bibliography --- p.202
42

Design and behavior of ribless solar reflectors

Hyde, Roderick Allen January 1976 (has links)
Thesis. 1976. Ph.D.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics. / Microfiche copy available in Archives and Barker. / Vita. / Includes bibliographical references. / by Roderick A. Hyde. / Ph.D.
43

Single molecule imaging to characterize protein interactions with the environment

Armstrong, Megan Julia January 2019 (has links)
In the past decade, single molecule imaging has advanced our understanding of processes at the molecular scale. Total internal reflection fluorescence (TIRF) microscopy is one implementation in particular that has been extensively applied in the study of protein adsorption to surfaces. The spatial and temporal resolution provided by TIRF has enabled dynamic measurements of individual proteins in solution, where previously only bulk measurements or static electron microscopy observations were possible. The ability to study individual proteins has revealed and sometimes clarified the complex interactions at their interfaces. Here, the utility of TIRF is expanded to introduce a new model of protein adsorption to the suface and to study the protein interface in contact with solution. Protein adsorption to surfaces has implications in surface biocompatibility, protein separation, and pharmaceutical nanoparticle development. For this reason, the phenomenon has been quantitatively by a variety of techniques, including single molecule imaging. The key data are the protein lifetimes on the surface, which have been shown to be broadly distributed and well-approximated by the sum of several exponential functions. The determined desorption rate constants are thought to reflect different interaction types between surface and protein, but the rates are not typically linked to a specific physical interaction. In the first part of this thesis, we establish appropriate imaging conditions and analysis methods for TIRF. A robust survival analysis technique is applied to capture the range of protein adsorption kinetics. In the second part, we utilize single molecule lifetime data from the adsorption of fibrinogen and bovine serum albumin (BSA) to glass surfaces and discover a heavy-tailed distribution: a very small fraction of proteins adsorbs effectively permanently, while the majority of proteins adsorb for a very short time. We then demonstrate that this characteristic power law behavior is well described by a model with a novel interpretation of the complex protein adsorption process. The second half of the thesis extends TIRF to study the solution-facing interface of the protein as opposed to the surface facing interface by establishing the parameters for a super-resolution imaging technique. Point accumulation for imaging nanoscale topography (PAINT) generates high-resolution images of the sample of interest through the positional tracking of many temporally-distinct instances of a fluorescent probe binding to the sample. Previously, this technique has been applied in the mapping of DNA nanostructures. Here, in the third part, we apply PAINT to the study of proteins. First, a workstream is established for a model system of Nile red and BSA. The kinetic parameters for the system are established to allow rational design of PAINT experiments with this system. The on-rate and off-rate for Nile red are determined. Additionally, the binding model between the two components is tested by studying how the presence of an inhibitor effects the parameters. In the final part, TIRF is used to study the protein-solution interface to examine the glycosylation of immunoglobulin A 1 (IgA1). Over 50% of eukaryotic proteins are glycosylated, and the glycan sequence is simultaneously difficult to study and crucial in the many functional roles proteins play. The glycosylation of IgA1, for example, plays a key role in the pathophysiology of IgA1 nephropathy. Lectins are proteins that bind to specifc glycan sequences and are often used to isolate glycosylated proteins. In this study, the appropriate surface conditions are established to allow specific binding between lectins and IgA1 glycans. The association and dissociation rate between lectins specific for the glycans on IgA1 are measured and affinity constants calculated. These efforts will help to rationally design experiments in the future to elucidate unknown glycan sequences on proteins.
44

Image-based illumination analysis and applications. / CUHK electronic theses & dissertations collection

January 2010 (has links)
Applications using image-based illumination analysis are very limited in the current literature of computer graphics. However, there are potentially more applications based on such analysis and estimation. In this thesis, we show two applications in computer graphics that can be directly benefited from using such analysis and estimation: photo colorization and texture synthesis. / Illumination is a very common phenomenon. All the photographs that we casually take with cameras exhibit such phenomenon. Computer graphicists usually simulate the illumination cast on objects based on physical models. While directly rendering such effects has been intensively studied in the field of computer graphics, the inverse estimation of illumination contribution to each pixel in the digital photographs, which we call image-based illumination estimation, still remains a challenging problem. The lack of the underlying geometry as well as the light source and material properties usually makes such inverse estimation ill-posed and a very difficult problem to solve. / In this thesis, we target on such image-based illumination estimation problem. We will review the current state-of-the-art illumination estimation algorithms for solving intrinsic images, and demonstrate their benefits and drawbacks. While this is a fundamental research problem in the field of computer vision, we show that by decomposing the image into its intrinsic components, the reflectance and illumination, many graphical applications can potentially be explored and benefited. In the meantime, we will also introduce a new and novel algorithm to efficiently estimate the intrinsic components based on the statistics of the textured regions. The same algorithm can also be directly applied to non-textured regions in an image. / Texture synthesis is a very fundamental problem in computer graphics. Current texture synthesis method is difficult to automatically take into account the illumination and deformation during the synthesis. By exploring the statistics of the texture, we propose a very efficient algorithm to estimate both the illumination and deformation fields on textures. The color of the illuminant is also taken into account so that the recovered reflectance has consistent color. By decomposing the illumination and deformation fields, we show that many texture-based applications, such as the preparation of texture exemplars from real photographs, the natural replacement of textured regions, the relighting of objects, as well as the manipulation of geometries in natural images can be well achieved, with the success of texture synthesis guided by illumination and deformation. / Traditional example-based colorization of natural images usually suffers from illumination inconsistency. The color transfer from areas such as highlights and shadows may severely harm the colorization result. We propose to consider the illumination problem in colorization and perform colorization in an illumination-free domain. The decomposition of the intrinsic components from multiple example images, as well as the recombination and utilization of these intrinsic components in colorization, form the foundation of the proposed technique. Consistent colorization results are obtained even though the example images are from different lighting conditions and viewing directions. / Liu, Xiaopei. / Adviser: Wong Tien Tsin. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 76-83). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
45

Reflection and Refraction of Light from Nonlinear Boundaries

Azadeh, Mohammad 04 October 1994 (has links)
This thesis deals with the topic of reflection and refraction of light from the boundary of nonlinear materials in general, and saturating amplifiers in particular. We first study some of the basic properties of the light waves in nonlinear materials. We then develop a general formalism to model the reflection and refraction of light with an arbitrary angle of incidence from the boundary of a nonlinear medium. This general formalism is then applied to the case of reflection and refraction from the boundary of linear dielectrics. It will be shown that in this limit, it reduces to the well known Fresnel and Snell's formulas. We also study the interface of a saturating amplifier. The wave equation we use for this purpose is approximate, in the sense that it assumes the amplitude of the wave does not vary significantly in a distance of a wave length. The limits and implications of this approximation are also investigated. We derive expressions for electric field and intensity reflection and transmission coefficients for such materials. In doing so, we make sure that the above mentioned approximation is not violated. These results are compared with the case of reflection and refraction from the interface of a linear dielectric.
46

Modeling and application of multispectral oceanic sun glint observations

Luderer, Gunnar 02 October 2003 (has links)
The atmospheric radiative transfer model MOCARAT was developed and is presented in this thesis. MOCARAT employs a Monte Carlo Technique for the accurate modeling of band radiances and reflectances in an atmospheric system with a ruffled ocean surface as a lower boundary. The atmospheric radiative transfer is modeled with consideration of molecular Rayleigh scattering, Mie Scattering and absorption on particulate matter, as well as band absorption by molecules in the wavelength channels of interest. The bidirectional reflection of downwelling light at the ocean surface is computed using the empirical relationship between surface wind field and the slope distribution of wave facets derived by Cox and Munk (1954a). A method is proposed to use the oceanic sun glint for remote sensing applications. The sensitivity of channel correlations to aerosol burden and type as well as other atmospheric and observational parameters is assessed. Comparisons of observed correlations with model results are used to check the consistency of the calibration of the airborne Multichannel Cloud Radiometer (MCR) that was employed during the Indian Ocean Experiment (INDOEX). The MCR calibration exhibited large variability from flight to flight. The method was applied to MODIS observations. Unlike the MCR, MODIS was stable where expected, although numerical values for some of the wavelengths appear to depart from theory. / Graduation date: 2004
47

Recherches sur la reflexion cristalline

Cornu, Alfred January 1900 (has links)
Thesis (doctoral)--Université de Paris, 1867. Thèse de doctorat : Physique : Paris, Faculté des sciences : 1867. / "No. d'ordre: 293" Titre provenant de l'écran-titre. Références bibliogr.
48

Highly integrated polymer photonic switching and interconnects

Wang, Xiaolong 28 August 2008 (has links)
Not available / text
49

Statistical ray-tracing analysis of the linear Fresnel mirror solar concentrator

Ying, Xiaomin January 1993 (has links)
The Monte Carlo-type statistical ray-tracing method was used to investigate the performance of the line-focusing Fresnel mirror solar concentrator. An optical model of the line-focusing Fresnel mirror concentrator using the statistical ray-tracing approach was developed. Many rays of sunlight from the solar disk were selected at random and traced through the concentrator in this model. This optical model permits calculation of the local and geometric concentration ratios. The latter requires an energyloss analysis. Small sun-tracking errors of the diurnal or transverse type were included in the model.Based on the optical model and the Monte Carlo-type statistical ray-tracing method, a computer program was written implementing the model and computations using Pascal. To facilitate performance comparisons, a baseline concentrator design was adopted. To study the effects of imperfect tracking, performance data were generated for small tracking errors up to approximately two and one-half degrees. The selected mirror configuration permitted comparisons between the statistical approach and previous applications of the "extreme ray" analysis for an imperfectly tracking mirror concentrator.Simulation results demonstrated that the concentration characteristics are highly sensitive to the tracking error. The geometric concentration ratio dramatically decreases when the tracking error increases, which is the same as the "extreme ray" analysis. Results of some typical numerical calculations are presented graphically and discussed. / Department of Physics and Astronomy
50

Analysis of tracking error effects for the Fresnel mirror solar concentrator

Zhan, Yong January 1989 (has links)
The solar concentration performance of a tracking, flat-base, line-focusing Fresnel mirror was investigated in this study. The Fresnel mirror consists of flat mirror strips situated on a base and oriented at appropriate angles to focus incident light to a desired line. Simple optical ray tracing and energy conservation were used to develop a mathematical model of the concentrator assuming small or zero diurnal tracking errors. The model analyzed the concentrator design and provided detailed expressions for the geometric evaluation of the concentrated sunlight rays in the focal plane above the mirror. The local concentration ratio and the geometric concentration ratio were introduced to describe the intensity profile in the focal plane and the average concentration of sunlight on a target absorber. Included in the model were losses of incident sunlight due to imperfect reflection, nonreflecting portions of the base, and blockage by adjacent mirror strips when imperfect tracking occurs.Based on the analytical model and using the Ada high level language, a computer program was written to simulate the concentrator. To facilitate performance comparisons, a baseline concentrator design was adopted. To study the effects of imperfect tracking, performance data were generated for small tracking errors up to approximately two and one-half degrees. The effects of design variations were studied by varying the concentrator focal length, strip width, and base width.Simulation results demonstrated that the concentration characteristics were highly sensitive to tracking error. Intensity profile shifts relative to the target caused the highest losses in intercepted sunlight.Design decisions were found to dramatically affect the concentration character- istics. For the baseline concentrator under perfect tracking conditions, an optimum focal length was identified. Except for the disadvantage of added costs, decreased strip widths was found to be a way to increase both the maximum and average concentration ratio for the absorber. Using smaller strip widths might, however, critically affect the energy intercepted by the target under imperfect tracking. Increasing the concentrator base width increased the total amount of power in the focal plane, with a higher maximum concentration ratio and additional tailing of the intensity profile. / Department of Physics and Astronomy

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