Dissertations / Theses on the topic 'Speculaur reflection'

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Materials are generally classified in terms of their constitutive parameters, the complex permittivity and permeability , in the frequency domain. These parameters are used to determine the response of materials to electromagnetic (EM) radiation. Materials found in nature have positive real parts for both and . In recent years, researchers have shown that a new class of materials called metamaterials (MTMs), characterized by inclusions of various shapes and materials that are small compared to wavelength, result in an effectively homogeneous medium with the unique properties of negative real and which cause EM waves traveling through the medium to exhibit unusual characteristics. Zero specular reflection layers for four material types such as double positive (DPS), double negative (DNG), epsilon-negative (ENG) and mu-negative (MNG) materials are examined in this thesis. For each defined type of MTM, the transcendental equations are derived and solved numerically to generate curves for zero specular reflection. A MATLAB program was developed to generate universal curves for DPS, DNG, ENG, and MNG materials. The results were discussed and evaluated to determine wave behavior in each type of MTM as well as how they can be used as a matched-surface radar-absorbing material (RAM) for military application. The results were compared to published data.

L'ostéoporose est une maladie caractérisée par une réduction de la masse osseuse et une augmentation de la porosité. Elle affaiblit les os et peut conduire à des fractures de fragilité. Globalement, 1/3 des femmes de plus de 50 ans et 1/5 des hommes de plus de 50 ans subiront des fractures liées à l'ostéoporose, contribuant à plus de 8,9 millions de fractures annuelles dans le monde. Ces fractures peuvent être prévenues si elles sont détectées et traitées suffisamment tôt. Plusieurs techniques ont été développées pour évaluer la qualité osseuse, l'échographie émergeant comme une option peu coûteuse, portable et sûre. L'imagerie par ultrasons du cortex des os longs permet l'évaluation de la qualité osseuse en estimant l'épaisseur corticale et la vitesse d'onde ultrasonore, des biomarqueurs de la résistance mécanique et du risque de fracture. Cependant, des défis se posent avec l'augmentation de la porosité corticale dans l'os ostéoporotique, rendant difficile la détection de la surface interne (endosteum) et limitant la qualité de l'image. L'objectif de ce travail est de concevoir une technique de reconstruction d'images capable d'améliorer les images échographiques de l'os cortical. Cela passe par la compréhension des facteurs influençant la qualité de l'image. Pour ce faire, des ensembles de données échographiques synthétiques et expérimentaux ont été générés. Nos résultats démontrent l'estimation réussie de l'épaisseur corticale et de la vitesse d'onde ultrasonore en utilisant l'imagerie par ultrasons pour un os cortical homogène. L'estimation in vivo de la vitesse d'onde au cortex tibial de sujets sains a atteint une précision de moins de 3%. Cependant, pour les os dégradés, une porosité corticale accrue et une taille de pore vasculaire plus grande créent un bruit qui obscurcit la visibilité de l'interface endostéale. Un nouvel algorithme de formation de faisceau spéculaire corrigé de la réfraction a été proposé pour améliorer la visibilité de l'interface endostéale. L'application de cet algorithme à la fois à des ensembles de données ex vivo et in vivo a révélé une visibilité améliorée par rapport à la formation de faisceau Delay-and-Sum (DAS) traditionnelle. Ce travail offre une meilleure compréhension des facteurs affectant le contraste des images échographiques osseuses et propose de considérer les diffuseurs comme des réflecteurs spéculaires pour améliorer la visibilité de l'interface endostéale. En évaluant la spécularité de l'interface endostéale, il devient possible d'évaluer potentiellement la rugosité de l'endosteum. Cela ouvre la voie à la conception de nouveaux quantificateurs de qualité mécanique osseuse. L'imagerie échographique osseuse montre des promesses dans l'identification et le suivi des personnes présentant une faible qualité mécanique osseuse corticale à risque de fracture ostéoporotique
Osteoporosis is a disease characterized by a decrease in bone mass and an increase in porosity, weakening the bones and potentially leading to fragility fractures. Globally, one-third of women over the age of 50 and one-fifth of men aged over 50 will experience osteoporosis-related fractures, contributing to over 8.9 million fractures annually worldwide. Early detection and treatment can prevent these fractures. Several techniques have been developed to assess bone quality, with ultrasound emerging as a cost-effective, portable, and safe option. Ultrasound imaging of the cortex of long bones allows for the evaluation of bone quality by estimating cortical thickness and ultrasonic wave-speed, which are biomarkers of mechanical strength and fracture risk. However, challenges arise with increased cortical porosity in osteoporotic bone, making it difficult to detect the inner surface (endosteum) and limiting image quality. The aim of this study is to design an image reconstruction technique to enhance ultrasound images of cortical bone. This involves understanding the factors influencing image quality. Synthetic and experimental ultrasound datasets were generated to achieve this. The results demonstrate successful estimation of cortical thickness and ultrasonic wave-speed using ultrasound imaging for homogeneous cortical bone. In vivo estimation of wave-speed at the tibial cortex of healthy individuals achieved a precision of less than 3%. However, for degraded bones, increased cortical porosity and vascular pore size create speckle that obscures the visibility of the endosteal interface. A novel refraction-corrected specular beamforming algorithm was proposed to improve the visibility of the endosteal interface. Application of this algorithm to both ex vivo and in vivo datasets revealed enhanced visibility compared to traditional Delay-and-Sum (DAS) beamforming. This study provides a better understanding of factors affecting bone ultrasound image contrast and proposes considering scatterers as specular reflectors to enhance endosteal interface visibility. By evaluating the specularity of the endosteal interface, it becomes possible to potentially assess the roughness of the endosteum. This opens a way for designing new bone mechanical quality quantifiers. Bone ultrasound imaging shows promise in identifying and monitoring individuals with low cortical bone mechanical quality at risk of osteoporotic fracture

This thesis introduces novel methods for estimating the poses of a reference plane from its reflections for specular surface recovery. Traditional methods for specular surface recovery usually introduce a second camera and an auxiliary calibration pattern to calibrate the poses of the reference plane with respect to the camera. The calibration procedures are comparatively tedious. Auto-estimating the poses of the reference plane is therefore an appealing problem. In the first part of this thesis, two novel and practical methods are proposed to recover the poses of a moving reference plane from its reflections produced on the specular surface given its initial position. As for the first approach, the reference plane is constrained to undergo an unknown pure translation. By observing the reflections of the moving reference plane produced on the specular surface, a closed form solution is derived for recovering the unknown translation. Degenerate cases in which the proposed method fails are studied. As for the second approach, the constraint on the motion of the reference plane is removed, and the reference plane can move freely. Again, a closed form solution is derived for the unknown motion defined by a rotation matrix and a translation vector, and the degenerate cases are also presented. The thesis finally considers the problem for auto-calibrating the reference plane against the camera for specular surface recovery without prior knowledge of the reference plane’s initial position. By only observing its reflections produced on the specular surface, the poses of the reference planes can be recovered in two steps. First, by applying a collinearity constraint to the specular correspondences, a simple closed form solution is derived for recovering the poses of the reference plane relative to its initial pose. Second, by applying a ray incidence constraint to the incident rays formed by the specular correspondences and the visual rays cast from the image, a closed form solution is derived for recovering the poses of the reference plane relative to the camera. The shape of the specular surface then follows.
published_or_final_version
Computer Science
Doctoral
Doctor of Philosophy

The thesis presented is an effort to gather all possible information of one particular type of common paint defect the seed defect, from gray scale images of highly specular painted surface. The proposed approach in the thesis utilizes a white light source to illuminate the surface and utilizes a camera to capture its gray scale image at different diffused angles. While attempting to explain the physics of highlight formation in terms of location on the surface of a seed defect, the thesis also extends to utilize this information from gray scale images to accurately predict the parameters of seed defects including the height, size and position in real time. Since the primary highlight in a gray scale image is more defined, contrary to the past researches on diffuse angle images that use both primary / seed highlight and mirror highlight to estimate height of the seed, this thesis formulates a theory of highlight translation and estimates the height of seed based on primary / seed highlight. The other common type of surface defect - crater defect, is also addressed in the thesis.

This thesis assessed the readability of CRT displays viewed under ambient lighting conditions and then evaluated the findings with respect to the ISO 9241-7 standard. More specifically, two phases of work were conducted in this thesis. In Phase 1, seven monitors were evaluated photometrically according to the ISO 9241-7 standard to determine whether they were Class I, II, or III in positive and negative polarity. Additionally, six filters were attached to each of the monitors and their ISO Class also was assessed. All monitor/filter combinations yielded either Class I or II in positive polarity and Class II, III or failed in negative polarity. In Phase 2, fourteen participants were asked to read Tinker passages from seven display/filter combinations (tested in Phase 1) under five lighting conditions and two screen polarities. The purpose of the Phase 2 was to determine if people perform differently for Class I, II, or III monitor/filter combinations. The dependent measures were the time to read the Tinker passage (reading time) and the ability to identify the out of context word in each passage (accuracy). An Analysis of Variance was used to determine the significant effects of reading time and accuracy. The ANOVA results indicate that specular glare interferes significantly more with reading time than does diffuse glare. Diffuse (200 lux) and Specular reading times also were correlated against two ISO metrics: screen image luminance ratio (Diffuse, 200 lux) and specular reflection luminance ratio. Reading times did not correlate with the screen image luminance ratio, but they did correlate with one of the ISO specular reflection luminance ratios. The results of this thesis indicate that the ISO standard should not equally weight the screen image and the specular reflection luminance ratios. Additionally, the results indicate that it is not necessary to have separate ISO Classes for positive and negative polarity. Furthermore, people did not read differently for Class I, II, or III monitor/filter combinations. Finally, the data of this investigation provide an initial human factors database for use in assessing the validity of ISO 9241-7.
Master of Science

Cílem mé diplomové práce bylo studium existujících metod pro detekci a odstranění odlesků ze sekvence snímků, nalezení jejich omezení a návrh možných vylepšení. Konkrétně jsme se zaměřili na rovinné spekulární povrchy, jejichž vzhled může být modelován superpozicí odrážené a přenášené vrstvy. Prozkoumali jsme především metody využívající vzájemný pohyb vrstev jako hlavní klíč k jejich oddělení. Popsali jsme jejich společný případ selhání, který spočívá v neschopnosti správného oddělení oblastí s nevýraznou texturou ve směru pohybu kamery. Výsledkem našeho úsilí je metoda řešící tento problém. Jejím hlavním přínosem je nový způsob odhadu hran obou vrstev, kdy důraz je kladen na správné oddělení hran zmíněných problematických oblastí. Věnovali jsme se také následnému odhadu barev jednotlivých vrstev, kdy se vedle hran vrstev využívá i odhad jejich hloubkových map, a popsali jsme alternativní přístup ke klasické kvadratické optimalizaci.

The increasing availability on the market of different types of solar reflectors such as: polymeric film mirrors, aluminum mirrors and thin glass mirrors, together with: the lack of available norms in this area, and a valid methodology to compare the performances of the candidate reflectors; highlights the necessity to conduct a more detailed analysis on these new technologies. The objective of the present work is to suggest a valuable method to compare the reflectance performance of mirrors, evaluating also their performances in order to assess: - the most durable to ageing and weathering effects; - the different reflectance behavior with the variation of the solar incident angle. .For these reasons the work here proposed was carried out with an experimental apparatus composed by: - An Agilent Cary 5000 UV/Vis/NIR spectrophotometer to test the different performance of the mirrors at different characterization steps; - An integrating sphere of 150 mm in diameter (DRA ¡V Diffuse Reflectance Accessory); - A VASRA (Variable Angle Specular Reflection Accessory); - A UV chamber to accelerate the ageing process; - A £gScan SMS Scatterometer for RMS Roughness and BDSF measurement; - An outdoor bench The work was completed with two modeling tools: - An engineering equation solver (Mathcad) to dynamically evaluate the behavior; - A ray tracing software (Soltrace) to evaluate the system¡¦s optical efficiency. The analysis indicates that the candidate reflectors can be accurately characterized with five fundamental parameters: a) £lSWH, the solar-weighted hemispherical reflectance; b) £lSWS, the solar-weighted specular reflectance; c) £lSWS( á), the solar weighted specular reflectance function of the variable angle of incidence; d) BDSF, Bi Directional Scattering Function; e) RMS Roughness This evaluation will provide a valuable tool, for the companies who want to invest in concentrating solar power technology, to decide whether or not using a candidate reflectors to realize new plants, assessing their performances, their costs, and their durability.

L'etude met en oeuvre la methode nodale, associee a celle des zones de hottel etendue au cas des reflexions speculaires et vitreuses par la methode du trajet des rayons. Les donnees spectroscopiques necessaires ont ete determinees experimentalement par la spectrometrie d'emission infrarouge. Application a l'identification de la diffusivite thermique a partir des champs de temperature determines par interferometrie

Espaços Especulares: articulações entre o real e o virtual é um estudo em artes visuais. O tema principal a partir do qual os trabalhos são baseados é a criação de relações entre espaços reais e espaços virtuais. Dois conceitos operatórios fundamentam a criação das obras: a utilização de reflexões especulares e o site-specific. Esses conceitos serão abordados de duas maneiras distintas: a utilização de espelhos em artes visuais através da noção de Espelho como Dispositivo; já o site-specific será relacionado ao conceito de Estética da Opacidade, ligado à teoria do cinema. O objeto de estudo é composto por dezenove obras criadas no período de 2008 a 2013. São trabalhos produzidos por meio de técnicas híbridas que utilizam procedimentos da arquitetura, computação gráfica e artes visuais. Como metodologia de pesquisa, serão analisados os processos e conceitos operatórios utilizados na produção relacionados com referenciais teóricos e práticos.
Specular Spaces: articulations between the real and the virtual is a study in visual arts. The main theme from which the work is based is creating relationships between real spaces and virtual spaces. Two creative concepts underlie the artistic process: the use of specular reflections and the site-specific. These concepts will be addressed in two different ways: the use of mirrors in the visual arts will be based on the notion of Mirror as a Device, whereas the site-specific is related to the concept of Aesthetics of Opacity, bound to film theory. The object of study is comprised of nineteen artworks created in the period of 2008 to 2013. They are artworks produced by hybrid techniques that utilizes procedures of architecture, computer graphics and visual arts. As a research methodology, the processes and creative concepts will be analyzed related to theoretical and practical examples.

Cette thèse s'inscrit dans le cadre de la simulation de particules colloïdales. Plus précisément, nous nous intéressons aux particules dans un écoulement turbulent et modélisons leur dynamique par un processus lagrangien, leurs interactions comme des collisions parfaitement élastiques où l'influence de l'écoulement est modélisée par un terme de force sur la composante vitesse du système. En couplant les particules deux par deux et considérant leurs position et vitesse relatives, la collision parfaitement élastique devient une condition de réflexion spéculaire. Nous proposons un schéma de discrétisation en temps pour le système Lagrangien résultant avec des conditions aux bords spéculaires et prouvons que l'erreur faible diminue au plus linéairement dans le pas de discrétisation temporelle. La démonstration s’appuie sur des résultats de régularité de l'EDP Feynman-Kac et requiert une certaine régularité sur le terme de force. Nous expérimentons numériquement certaines conjectures, dont l’erreur faible diminuant linéairement pour des termes de force qui ne respectent pas les conditions du théorème. Nous testons le taux de convergence de l’erreur faible pour l’extrapolation de Romberg. Enfin, nous nous intéressons aux approximations Lagrangiennes/Browniennes en considérant un système Lagrangien où la composante vitesse se comporte comme un processus rapide. Nous contrôlons l'erreur faible entre la composante position du modèle Lagrangien et un processus de diffusion uniformément elliptique. Nous démontrons ensuite un contrôle similaire en introduisant une limite réfléchissante spéculaire sur le système Lagrangien et une réflexion appropriée sur la diffusion elliptique
This thesis broadly concerns colloidal particle simulation which plays an important role in understanding two-phase flows. More specifically, we track the particles inside a turbulent flow and model their dynamics as a stochastic process, their interactions as perfectly elastic collisions where the influence of the flow is modelled by a drift on the velocity term. By coupling each particle and considering their relative position and velocity, the perfectly elastic collision becomes a specular reflection condition. We put forward a time discretisation scheme for the resulting Lagrange system with specular boundary conditions and prove that the convergence rate of the weak error decreases at most linearly in the time discretisation step. The evidence is based on regularity results of the Feynman-Kac PDE and requires some regularity on the drift. We numerically experiment a series of conjectures, amongst which the weak error linearly decreasing for drifts that do not comply with the theorem conditions. We test the weak error convergence rate for a Richardson Romberg extrapolation. We finally deal with Lagrangian/Brownian approximations by considering a Lagrangian system where the velocity component behaves as a fast process. We control the weak error between the position of the Lagrangian system and an appropriately chosen uniformly elliptic diffusion process and subsequently prove a similar control by introducing a specular reflecting boundary on the Lagrangian and an appropriate reflection on the elliptic diffusion

La reflectivite des rayons x par des multicouches planaires et structurees est presentee en utilisant differentes approches theoriques. Les phenomenes de diffusion etudies sont : la reflectivite speculaire par des multicouches planaires ayant diverses sequences d'empilement (monocouche, periodique, quasiperiodique), la diffusion diffuse de multicouches rugueuses, et enfin la diffusion par des reseaux de surface et par des reseaux de multicouche. Les theories employees pour les calculs : la theorie cinematique, l'approximation de l'onde deformee de born, la theorie dynamique, et plusieurs approximations de la theorie dynamique (approximation a une reflexion unique, approximation a deux ondes et approximation a diffusion multiple), sont developpees dans un formularisme unique. Ce formalisme permet de discuter et de comparer toutes les theories d'une maniere solide et methodologique. Les calculs numeriques sont appliques pour l'ajustement des courbes experiementales pour mettre en evidence les parametres structuraux des divers systemes multicouches.

Avec l’émergence des nouveaux aciers chargés en éléments réactifs, la caractérisation des états de surface a pris une nouvelle dimension. En effet, différentes familles d’oxyde sont dommageables pour la qualité de surface de l’acier et peuvent nuire à l’application de revêtements annexes. Aussi, afin d’assurer une bonne qualité aux produits finis, le besoin de caractériser, en ligne, la surface de l’acier sur toute sa largeur est de plus en plus nécessaire. L’imagerie hyperspectrale est une technologie en plein essor qui permet à la fois la caractérisation spatiale et spectrale d’une surface. Elle n’avait cependant encore jamais été employée pour la caractérisation de couche mince dans l’industrie sidérurgique. Durant ma thèse, deux méthodologies ont ainsi été développées pour répondre à ce besoin: l’une via une mesure en réflexion spéculaire et l’autre via une mesure en émission. En complément d’un travail de synthèse d’échantillons de référence, un développement expérimental complet allant d’un banc de simulation aux traitements des données a été réalisé. Ce travail a permis de démontrer la capabilité de l’imagerie hyperspectrale pour la détection de couche mince d’oxyde sur un acier parfois à plusieurs centaines de degrés Celsius. Ces résultats encourageants ont conduit à réaliser la première implantation industrielle de cette technologie. Ce travail de thèse a permis d’étudier théoriquement et expérimentalement les phénomènes mis en jeu et de passer du concept répondant à un besoin industriel à l’implémentation en ligne d’un capteur dédié à la caractérisation d’une couche mince d’oxyde sur une surface en défilement dans des conditions industrielles
With the emergence of new steel loaded in reactive elements, the characterization of the physico-chemical properties of the surface states has taken a new dimension. Indeed, the thin films of oxide formed are damaging for the surface quality of the steel and may adversely affect the application of varied coatings. Also, to ensure a good quality on finished products, the need to characterize, online, the steel surface over its entire width is increasingly necessary. The hyperspectral imaging is an emerging technology that allows both spatial and spectral characterization of a surface. It had never been used to characterize thin layers in the steel industry. During my PhD, both methodologies have been developed to meet this need: one via a measurement in specular reflection and the other via a measurement in emission. In addition to a synthesis of reference samples, a full experimental development ranging from a simulation bench to the data processing was performed. This work has demonstrated the capability of the hyperspectral imaging to detect thin surface oxide layers on a steel surface, sometimes at several hundred degrees Celsius. These encouraging results led to the first industrial implementation of this technology. This thesis made it possible to study theoretically and experimentally the phenomena involved and to move from the concept that meets an industrial need to the implementation of an online sensor dedicated to the characterization of a thin oxide layer on a moving surface in industrial conditions

碩士
國立臺灣大學
資訊網路與多媒體研究所
101
In this thesis, we proposed a specular reflection removal method based on logical estimation to deal with two specular images with the same scene but with different specular regions. Assume the two input images contain some complementary information. They can reference each other to recover the specular region. Even if there is a specular region appearing in both images, our method still can remove specularity and recover the structure in the image. At first, we use Scale-Invariant Feature Transform to describe the features of two input images and employ information to warp one of two input images to another one. According to the matching relationship of the feature points, we generate a specular-overlap image and a specular-union image. Then, we use these two images to fit a logical estimation model and find the specular region in both specular-overlap image and specular-union image. Finally, we recover the specular region of specular-overlap image by applying color transformation and color blending. Our results show that the proposed method has removed the specular reflection and recover the structure of contents in the specular region automatically.

碩士
國立臺灣科技大學
電子工程系
94
Display is among the most important in the nowadays significant opto-electric industry. Because the liquid crystal is not self-illuminated, it needs an outer light source to operate. Therefore, BLU is the most important part in LCD display and it had been developed several type of BLU carter to demand for market. BLU (Back Light Unit) plays an important role in display. Most of edge lighting BLUs use dot patterns or similar ways to gain uniformity via scattering. In this article, we use mirrors to achieve uniformity. Mirrors reduce the energy loss of source and easier to analyze. In this article, we employ the CCFL for light source of edge lighting BLU, and we use the specular reflection instead of dot patterns for uniformity. This method reduces the energy loss and is easier to analyze. Although parameters (relative position,θ…) adjusting is necessary, the proposed system is suitable for any reflector. As long as the reflected rays are concurrent, the proposal design is independent of reflectors shape and will achieve more uniformity and reduce energy loss.

碩士
國立交通大學
多媒體工程研究所
103
Nowadays counterfeit money has increased to an unacceptable level in Taiwan, especially for fifty dollar coins. As the techniques of counterfeit become more advanced, many traders cannot effectively distinguish the money between authentic or counterfeit. In order to prevent the counterfeit money from running rampant, we propose an image analysis method based on the change of specular reflection of a coin. It is verified through experiments that the proposed approach, and the implement prototype machine, can effectively and efficiently distinguish authentic and counterfeit coins. We hope the proposed approach can prevent effectively suppress the amount of counterfeit money in our society.

碩士
國立成功大學
機械工程學系
107
The main purpose of this study is to measure the specular profile using two different fringe reflection methods as well as exploring the differences between the two methods. The two methods performed in this experiment include the vector method and the normal vector method. They are used to measure the wafer and the male die as well as the female die, respectively. Finally, the results of these experiments are then compared using the surface roughness meter and displacement sensor. The root-mean-square error (henceforth, RMSE) of the wafer with 30 μm of range of height is found to be within 1.69 μm. The RMSE of the male die and female die with 18 mm of range of height is found to be within 0.22 mm. In the experiment, it is observed that the larger the pitch of fringe, the more visible the wave profile of the specimen. In order to avoid the slope of the specimen being too large, which may ultimately cause the camera to not be able to clearly observe the image on the screen from the specimen. The specimen must be properly tilted. When integrating the x-direction of the slope of a female die, the female die geometry relationship will cause integrations that occur only in horizontal directions to commit integral errors. It should be priorly determined whether or not the geometry of the specimen will cause the slope in the central axis of the integral or the area near it to be absent. If the slope is indeed absent, the area where the slope exists should be integrated first, followed by integrating the area where the slope does not exist. It is also necessary to find the adjacent slope point in the direction of such integration then search for the integration result of the surrounding from the slope point. Continue the integration until all the slope points have completed their respective integration.

碩士
國立交通大學
顯示科技研究所
102
Specular reflection is an important issue for an iris acquisition imaging system. This thesis is aimed to investigate the influence of near IR source on the image quality as well as optimizing arrangement of light source to enhance segmentation process. The arrangement of the light source manipulates the specular positions on iris region. More specifically, by controlling the geometric relations of subject, light source and image acquisition is able to avoid the specular reflections overlapping with iris information region. In this thesis, we proposed a complete geometric model to predict the specular reflections. The effectiveness and practicability of the proposed modeling have been validated by a series of experimental testing.

碩士
國立雲林科技大學
電機工程系
104
Specular reflection in endoscopy is annoying to physicians when performing Minimally Invasive Surgery (MIS). A spatial domain inpainting techniques was proposed last year for reflection removal in laparoscopy, in this thesis, our goal is to extend the spatial domain technique to the use of temporal domain information based on the observation that the locations of specular reflections are varying when the camera is moving, thus, reflections in current frame may be normal (non-reflection) in previous frames. Therefore, the idea is to search through the original previous 2Nth frames (N=1:10) for the key frame which has maximum non-reflection (normal) pixels in the current reflection areas, then match current frame to the key frame using registration technique, the reflection areas in current frame are compensated by coping from the reflection removed (compensated ) key frame. Since the illuminations in the reflection area in current frame and key frame may be different, we developed a illumination compensation technique to compensate the illumination difference. All pixels in the reflection area in the first frame as well as the pixels in the current frame but not overlapped by the key frame are marked and compensated using spatial domain inpainting technique proposed last year.

碩士
國立臺北科技大學
機械工程系機電整合碩士班
106
Since the surface of the cylinder (golf club) has up to 14 kinds of defects with different type of sizes, directions, and locations, this paper designs two kinds of lighting systems for defect detection on the surface of the club through the three-dimensional rendering software simulation lighting systems structure. However, the surface of golf club was electroplated with high specular reflection characteristics. Therefore, the design of lighting system was required to avoid the external lighting system affecting the image quality of the club in this paper. The first lighting system developed a light-shielding element with an one-side slit observation hole above the circular tube. Moreover, the light-shielding element could pre-vent the light from being highly reflective coverage of the club and generate the dark area to defect inspection. The second lighting system had used a linear diffused to detect inspection in the radial depth of the club surface. The experimental results show that both lighting sys-tems can be applied to high-mirror and high reflection surface objects for defect detection. The first light source system has a defect accuracy of 71.9%, and the second light source system has a defect accuracy of 82.5%.

碩士
國立交通大學
多媒體工程研究所
105
With the increased on counterfeit money of market, especially for fifty dollar coin. Many people cannot effectively distinguish the money between real or counterfeit, which forced the unscrupulous vendor who manufacture counterfeit money has run rampant. In order to prevent the counterfeit money from increasing, we are engaged in research for this area. We propose an image processing method that based on intensity change of a coin. The proposed approach and the corresponding machine can effectively and efficiently distinguish coin. We hope the proposed approach can prevent the counterfeit money in our life.

碩士
國立臺灣師範大學
資訊工程學系
104
Physically based image synthesis aims to render realistic images. It is widely used in many industries, e.g., Computer-generated imagery (CGI) in the movie industry, 3D models preview in the architecture and the design industry, and of course, 3D scenes in the computer gaming industry. In the real world, the information of light is infinite; therefore, we must do sampling to estimate it. How to deal with the global illumination effect plays an important role in whether the rendered image looks real or not. There are many sampling methods that reveal different features of the scene. Bidirectional path tracing, which is one of the Monte Carlo path tracing methods, is known for its quick convergence; however, due to innate limitation, it cannot handle some difficult cases, such as specular-diffuse-specular (SDS) paths. In this thesis, we introduce an alternative path reuse method while facing the SDS problem during the operation.

碩士
國立中正大學
電機工程研究所
106
Endoscopes are used for a wide range of purposes. The endoscope is mainly composed of a light source and a lens. Endoscopes are often used for examinations inside the body, such as the large intestine, stomach, etc. In addition to in vivo examination of the human body, minimally invasive surgery is also an endoscope-related application. Compared with the traditional surgery, minimally invasive surgery has the advantages of small wound and quick recovery. Minimally invasive surgery is performed through an endoscope. The light source and lens of the endoscope can be used to display the current situation from a monitor. The physician can treat or observe through the endoscope. Since the surface of the internal organs is full of water, when the endoscope is used, the light source will have water reflection when it hits the surface of the organ. We call it Specular reflection. This Specular reflection will affect the doctor's diagnosis. This can cause shadowing to the organs. But most of the current literature focuses on the use of Inpainting. The method is to use the surrounding information to fill the Specular reflection. The result of this method is not the actual situation on the surface of the organ, and it is difficult for the doctor to believe. This paper uses a background Sprite model to reconstruct the Specular reflection. First, the Specular reflection will be detected and marked first. Next, we will calculate the Global motion estimation(GME) parameter. Integrate the endoscope image into the background Sprite model and form a progressive background Sprite model. Finally, get information from the momentary background Sprite model and reconstruct the Specular reflection. The experiment result shows, this paper can effectively reconstruct the specular reflection and reconstructive result is actually the surface of the organ. However, the specular reflection of the endoscope image is not homogeneous, the effect of reconstruction can be strengthened.

Almost once a week broadcasts about earthquakes, hurricanes, tsunamis, or forest fires are filling the news. While oneself feels it is hard to watch such news, it is even harder for rescue troops to enter such areas. They need some skills to get a quick overview of the devastated area and find victims. Time is ticking, since the chance for survival shrinks the longer it takes till help is available. To coordinate the teams efficiently, all information needs to be collected at the command center. Therefore, teams investigate the destroyed houses and hollow spaces for victims. Doing so, they never can be sure that the building will not fully collapse while they are inside. Here, rescue robots are welcome helpers, as they are replaceable and make work more secure. Unfortunately, rescue robots are not usable off-the-shelf, yet. There is no doubt, that such a robot has to fulfil essential requirements to successfully accomplish a rescue mission. Apart from the mechanical requirements it has to be able to build a 3D map of the environment. This is essential to navigate through rough terrain and fulfil manipulation tasks (e.g. open doors). To build a map and gather environmental information, robots are equipped with multiple sensors. Since laser scanners produce precise measurements and support a wide scanning range, they are common visual sensors utilized for mapping. Unfortunately, they produce erroneous measurements when scanning transparent (e.g. glass, transparent plastic) or specular reflective objects (e.g. mirror, shiny metal). It is understood that such objects can be everywhere and a pre-manipulation to prevent their influences is impossible. Using additional sensors also bear risks. The problem is that these objects are occasionally visible, based on the incident angle of the laser beam, the surface, and the type of object. Hence, for transparent objects, measurements might result from the object surface or objects behind it. For specular reflective objects, measurements might result from the object surface or a mirrored object. These mirrored objects are illustrated behind the surface which is wrong. To obtain a precise map, the surfaces need to be recognised and mapped reliably. Otherwise, the robot navigates into it and crashes. Further, points behind the surface should be identified and treated based on the object type. Points behind a transparent surface should remain as they represent real objects. In contrast, Points behind a specular reflective surface should be erased. To do so, the object type needs to be classified. Unfortunately, none of the current approaches is capable to fulfil these requirements. Therefore, the following thesis addresses this problem to detect transparent and specular reflective objects and to identify their influences. To give the reader a start up, the first chapters describe: the theoretical background concerning propagation of light; sensor systems applied for range measurements; mapping approaches used in this work; and the state-of-the-art concerning detection and identification of transparent and specular reflective objects. Afterwards, the Reflection-Identification-Approach, which is the core of subject thesis is presented. It describes 2D and a 3D implementation to detect and classify such objects. Both are available as ROS-nodes. In the next chapter, various experiments demonstrate the applicability and reliability of these nodes. It proves that transparent and specular reflective objects can be detected and classified. Therefore, a Pre- and Post-Filter module is required in 2D. In 3D, classification is possible solely with the Pre-Filter. This is due to the higher amount of measurements. An example shows that an updatable mapping module allows the robot navigation to rely on refined maps. Otherwise, two individual maps are build which require a fusion afterwards. Finally, the last chapter summarizes the results and proposes suggestions for future work
Fast schon wöchentlich füllen Meldungen über Erdbeben, Wirbelstürme, Tsunamis oder Wald-brände die Nachrichten. Es ist hart anzusehen, aber noch viel härter trifft es die Rettungskräfte, welche dort zum Einsatz gerufen werden. Diese müssen gut trainiert sein, um sich schnell einen Überblick verschaffen zu können und um den zerstörten Bereich nach Opfern zu durchsuchen. Zeit ist hier ein seltenes Gut, denn die Überlebenschancen sinken, je länger es dauert bis Hilfe eintrifft. Für eine effektive Teamkoordination werden alle Informationen in der Einsatzzentrale gesammelt. In Trupps wird nach Opfern gesucht. Hierfür werden die zerstörten Gebäude durchsucht und alle Hohlräume inspiziert. Dabei können die Helfer oft nicht darauf vertrauen, dass die Gebäude stabil sind und nicht noch vollständig kollabieren. Hier sind Rettungsroboter eine willkommene Hilfe. Sie sind ersetzbar und können für gefährliche Aufgaben verwendet werden. Dies macht die Arbeit der Rettungstrupps sicherer. Allerdings gibt es solche Roboter noch nicht von der Stange. Sie müssten gewisse Anforderungen erfüllen, dass sie in einem solchen Szenarien einsetztbar sind. Neben Ansprüchen an die Mechanik, müsste eine 3D-Karte des Einsatzgebietes erstellen werden. Diese ist Grundlage für eine erfolgreiche Navigation (durch unebenes Terrain), sowie zur Beeinflussung der Umgebung (z.B. Tür öffnen). Die Umgebungserfassung wird über Sen-soren am Roboter durchgeführt. Heutzutage werden bevorzugt Laserscanner dafür verwendet, da sie präzise Messdaten liefern und über einen großen Messbereich verfügen. Unglücklicherweise werden Messdaten durch transparente (z.B. Glas, transparenter Kunststoff) und reflektierende Objekte (z.B. Spiegel, glänzendes Metall) verfälscht. Eine Vorbehandlung der Umgebung (z.B. abdecken der Flächen), um diese Einflüsse zu verhindern, ist verständlicherweise nicht möglich. Zusätzliche Sensoren zu verwenden birgt ebenfalls Nachteile. Das Problem dieser Objekte liegt darin, dass sie nur teilweise sichtbar sind. Dies ist abhängig vom Einfallwinkel des Laserstrahls auf die Oberfläche und vom Typ des Objektes. Dementsprechend könnnen die Messwerte bei transparenten Flächen von der Oberfläche oder vom Objekten dahinter resultieren. Im Gegensatz dazu können die Messwerte bei reflektierenden Oberflächen von der Oberfläche selbst oder von einem gespiegelten Objekt resultieren. Gespiegelte Objekte werden dabei hinter der reflektierenden Objerfläche dargestellt, was falsch ist. Um eine präzise Kartierung zu erlangen, müssen die Oberflächen zuverlässig eingetragen werden. Andernfalls würde der Roboter in diese navigieren und kollidieren. Weiterhin sollten Punkte hinter der Oberfläche abhängig von der Oberfläche behandelt werden. Bei einer trans- parenten Oberfläche müssen die Punkte in die Karte eingetragen werden, weil sie ein reelles Objekt darstellen. Im Gegensatz dazu, müssen bei einer reflektierenden Oberfläche die Messdaten dahinter gelöscht werden. Dafür ist eine Unterscheidung der Objekte zwingend. Diese Anforderungen erfüllen die momentan verfügbaren Algorithmen jedoch nicht. Aus diesem Grund befasst sich folgende Doktorarbeit mit der Problematik der Erkennung und Identifizierung transparenter und spiegelnder Objekte, sowie deren Einflüsse. Um dem Leser einen Einstieg zu geben, beschreiben die ersten Kapitel: den theoretischen Hindergrund bezüglich des Verhaltens von Licht; Sensorsysteme für die Distanzmessung; Kartierungsalgorithmen, welche in dieser Arbeit verwendet wurden; und den Stand der Technik bezüglich der Erkennung von transparenten und spiegelndend Objekten. Danach wird der Reflection-Identification-Algorithmus, welcher Basis dieser Arbeit ist, präsentiert. Hier wird eine 2D und eine 3D Implementierung beschrieben. Beide sind als ROS-Knoten verfügbar. Das anschließende Kapitel diskutiert Experimente, welche die Anwendbarkeit und Zuverlässigkeit des Algorithmus verifizieren. Für den 2D-Fall ist ein Vor- und ein Nachfilter-Modul notwendig. Nur mittels der Nachfilterung ist eine Klassifizierung der Objekte möglich. Im Gegensatz kann im 3D-Fall die Klassifizierung bereits mit der Vorfilterung erlangt werden. Dies beruht auf der höheren Anzahl an Messdaten. Weiterhin zeigt dieses Kapitel beispielhaft eine Adaptierung des TSD-SLAM Algorithmus, so dass der Roboter auf einer aktualisierten Karte navigieren kann. Dies erspart die Erstellung von zwei unabhängigen Karten und eine anschließende Fusionierung. Im letzten Kapitel werden die Ergebnisse der Arbeit zusammengefasst und ein Ausblick mit Anregungen zur Weiterarbeit gegeben

Steady-state sound fields in enclosures, with specular and diffuse reflection boundaries, are modeled with a first-principle energy-intensity boundary element method using uncorrelated broadband directional sources. The specular reflection field is represented by a limited set of spherical harmonics that are orthogonal on the half-space. The amplitudes of these harmonics are determined by a Lagrange multiplier method to satisfy the energy conservation integral constraint. The computational problem is solved using an iterative relaxation method starting from the 3-D diffuse reflection solution. At each iteration, directivity harmonics are estimated by post-processing and the influence matrix is refined accordingly. For internal sources, simple first reflection images improve accuracy with virtually no penalty on computation time. Monotonic convergence occurs in relatively few relaxation steps. Extrapolating to an infinite number of boundary elements and iterations gives very accurate results. The method is very computationally efficient. Results are compared to exact benchmark solutions obtained from a frequency-by-frequency modal analysis, and a broadband image method, demonstrating high accuracy. The method of absorption scaling is verified for complicated 3-D cases, and showing that the spatial variation in rooms is largely determined by source position and the relative distribution of absorption, but not the overall absorption level.

Dissertation

Το αντικείμενο αυτής της διπλωματικής εργασίας είναι ο διαχωρισμός των δύο κυρίαρχων συνιστωσών ανάκλσης (κατοπτρικής και διάχυτης) που οφείλονται κυρίαρχα σε επιφάνειες διηλεκτρικών υλικών. Οι κατοπτρικές ανακλάσεις αποτελούν σημαντικό πρόβλημα για πολλούς αλγορίθμους στο πεδίο της "τεχνητής όρασης" όπως στην κατάτμηση εικόνας. Μετά την ανάλυση του προβλήματος και μία εισαγωγή στη χρωματομετρία και στην πόλωση ακολουθεί μία περιγραφή δημοφιλών μεθόδων που έχουν προηγηθεί πάνω σε αυτό το αντικείμενο. Τέλος, παρουσιάζουμε τη δική μας μέθοδο διαχωρισμού, η οποία εκμεταλλεύεται τα διαφορετικά χαρακτηριστικά πολώσεως των δύο συνιστωσών και με τη βοήθεια της ανάλυσης ανεξαρτήτων συνιστωσών (ICA) επιτυγχάνει το διαχωρισμό. Η μέθοδος εφαρμόζεται τόσο σε πραγματικές όσο και σε κατασκευασμένες εικόνες.
The subject of this thesis is the separation of two reflection components (specular and diffuse) on surfaces of dielectric materials. The specular reflections are a significant problem for many algorithms in the field of computer vision, i.e. image segmentation. After the analysis of the problem and an introduction to colorimetry and polarization we describe popular methods that have already been used for this problem. Finally, we represent our own separation method, which exploits the different degree of polarization in the two reflection components and achieves the separation using independent component analysis (ICA). The method is applied on both real and virtual images.

Fringe-pattern projection (FPP) techniques are commonly used for surface-shape measurement in a wide range of applications including object and scene modeling, part inspection, and reverse engineering. Periodic intensity fringe patterns with a specific amplitude are projected by the projector onto an object and a camera captures images of the fringe patterns, which appear distorted by the object surface from the perspective of the camera. The images are then used to compute the height or depth of the object at each pixel. One of the problems with FPP is that camera sensor saturation may occur if there is a large change in ambient lighting or a large range in surface reflectivity when measuring object surfaces. Camera sensor saturation occurs when the reflected intensity exceeds the maximum quantization level of the camera. A low SNR occurs when there is a low intensity modulation of the fringe pattern compared to the amount of noise in the image. Camera sensor saturation and low SNR can result in significant measurement error. Careful selection of the camera aperture or exposure time can reduce the error due to camera sensor saturation or low SNR. However, this is difficult to perform automatically, which may be necessary when measuring objects in uncontrolled environments where the lighting may change and objects have different surface reflectivity. This research presents three methods to avoid camera sensor saturation when measuring surfaces subject to changes in ambient lighting and objects with a large range in reflectivity. All these methods use the same novel approach of lowering the maximum input gray level (MIGL) to the projector for saturation avoidance. This approach avoids saturation by lowering the reflected intensity so that formerly saturated intensities can be captured by the camera. The first method of saturation avoidance seeks a trade-off between robustness to intensity saturation and low SNR. Measurements of a flat white plate at different MIGL resulted in a trade-off MIGL that yielded the highest accuracy for a single adjustment of MIGL that is uniform within and across the projected images. The second method used several sets of images, taken at constant steps of MIGL, and combined the images pixel-by-pixel into a single set of composite images, by selecting the highest unsaturated intensities at each pixel. White plate measurements using this method had comparable accuracy to the first method but required more images to form the composite image. Measurement of a checkerboard showed a higher accuracy than the first method since the second method maintains a higher SNR when the object has a large range of reflectivity. The last method also used composite images where the step size was determined dynamically, based on the estimated percentage of pixels that would become unsaturated at the next step. In measurements of a flat white plate and a checkerboard the dynamic step size was found to add flexibility to the measurement system compared to the constant steps using the second method. Using dynamic steps, the measurement system was able to measure objects with either a low or high range of reflectivity with high accuracy and without manually adjusting the step size. This permits fully automated measurement of unknown objects with variable reflectivity in unstructured environments with changing lighting conditions. The methods can be used for measurement in uncontrolled environments, for specular surfaces, and those with a large range of reflectivity or luminance. This would allow a wider range of measurement applications using FPP techniques.

碩士
國立臺灣科技大學
建築系
100
Color and specular reflection are the important in interior design and also have different meaning and value in our life. Color and specular reflection influent the atmosphere of interior space and bring the effect of human. In this study, the relationship between color, specular reflection, interior space and human perception are discussed. the experiment 1 is about the interior space without funiture and the participants are required to compare 9 rooms (3 different colors: blue, yellow and white；and 3 different specular reflection: 0.1, 0.45, and 0.8). The experiment 2 is about the residential interior space with funiture and the participants are required to compare 16 rooms ( 4 function: living room, bedroom, dining room and study room; in 4 type: blue 0.45, yellow 0.1, white 0.45 and color 0.1). The experiments are proceeded in qestionaires and 3d rendered pictures. The result in experiments figure out the participants in different background such as different gender, ages, eyes color, architecture, interior background and different country have different perception of different spaces. Most paricipants can not accept high specular reflection in the interior space. In the residential interior, most participant have more positve emotion in the yellow type design. The purpose of his research is helping designers to understand the spatial perception and the preference of color and spacular refleciton in interior design of differents users and to expect the designer can create perfected interior space in the future.

The aim of this diploma thesis is the application of vibrational spectroscopy in pharmaceutical analysis in studying solid pharmaceutical forms. The surface of tablet samples containing the active substance from the group of statins has been studied especially by the methods infrared microscopy. Spectral maps of samples were collected thanks to the techniques of specular reflection, attenuated total reflection (ATR) and "inverse" ATR after determining optimal conditions for measurements. In order to evaluate these measured maps, one-dimensional analysis and principal component analysis were used. As the same samples of tablets were also measured by Raman microscopy, the comparison has been provided. The measured distribution maps enable both a determination of substances in the sample and conclusion concerned a method of tablets' preparation. The method in this case is a granulation, which has been found out from a comparison of maps of generic and original medicament. The specular reflection method was selected to be the most appropriate technique for obtaining the maps of the surface of a tablet, via confrontation of particular methods consequently with consideration of their advantages and disadvantages in the measurement and data processing.

A obra de Michelangelo Pistoletto expõe a própria ideia de espelho, propondo ao mesmo tempo dispositivos especulares no seu trabalho e um meta-discurso sobre a arte enquanto espelho. O seu trabalho conduziu-nos a pensar sobre outras situações de arte contemporânea, ou apenas artísticas em geral. Que reflectem as obras? Como é que reflectem? Apercebemo-nos rapidamente de que a qualidade de “reflectir” no seu duplo sentido, é reconduzível a uma só, por entre tantas outras qualidades dos espelhos e das obras como espelho. Torna-se então necessário substituir aquelas duas perguntas por duas outras: o que fazem as obras quando funcionam como espelhos? E como é que o fazem? Para além de “reflectir” (em francês seriam duas palavras diferentes: “refléter” e “réfléchir”) e para além da sua qualidade reflectora, dão-nos a ver outras qualidades: mnésicas, simbólicas, narrativas, geométricas, algébricas, interpeladoras, reveladoras, auto-reflexivas e meta-discursivas. Chamámos a esse conjunto qualidades especulares das obras (“qualités miroiriques”: em francês o termo é pedido de empréstimo a Duchamp): qualidades do espelho, todas elas. Analisámos o seu funcionamento nas obras, com o auxílio das de Pistoletto e mantendo a preocupação de as pensar a partir de um observador que delas usufrui. A metáfora corrente que pretende que a arte reflecte a vida guiou-nos na convicção de que um objecto ou uma experiência artística só existem para o receptor quando lhes reenviam imagens e possibilidades de si mesmo e do seu mundo; de que a experiência do duplo é menos uma experiência de reprodução do que uma experiência que o alimenta de si próprio. As múltiplas qualidades especulares das obras equivalem ao seu potencial mobilizador; elas conduziram-nos a procurar as formas de vitalidade que se desenham no interior dessa mobilização; ou seja, a retomar o debate, que pareceria esgotado, sobre as relações entre a arte e a vida. Um debate que só nos interessou na medida em que o ponto de vista das qualidades especulares desloca o seu paradigma dual: aquele em que se perfilam as oposições viciadas subjectivo / objectivo, expressionismo / inexpressionismo, expressão / empenho social, contemplação / participação, coisas / imagens, bidimensional / tridimensional, autonomia / utilidade, formalista / referencial, e outras próximas destas. Não há arte em que a vida não esteja inscrita. O que varia são os pontos de vista, as leituras e o tipo de “vida” que se procura ou se denega nela. A obra de Pistoletto fornece-nos exemplos eloquentes. A selecção que fizemos inclui obras tão díspares como objectos, acções ou textos escritos. A sua obra escrita é informativa, literária, programática e plástica, o que não deixa de colocar alguns problemas à abordagem interpretativa. As revelações trazidas pelos seus espelhos literais e metafóricos remetem ainda para as questões da moldura, da pintura, da representação, do sujeito, do auto-reconhecimento e da participação na obra.
L’œuvre de Michelangelo Pistoletto expose l’idée même de miroir, en proposant à la fois des dispositifs miroiriques dans son travail et un méta discours sur l’art en tant que miroir. J'ai cru y trouver l’occasion de me poser des questions sur son œuvre qui peuvent peut-être servir à penser d'autres situations d'art contemporain, ou d'art tout court. Que reflètent les œuvres? Comment le reflètent-elles? En essayant de répondre à ces deux questions, on s'aperçoit vite que la qualité de refléter ou de réfléchir n'en est qu'une, parmi d'autres qualités des miroirs, et des œuvres en tant que miroirs. Il faut alors remplacer ces questions par deux autres: Que font les œuvres quand elles fonctionnent comme des miroirs? Et comment? Ce qu'elles font, outre réfléchir et refléter, outre leur qualité réfléchissante, nous montre leurs autres qualités: mnésiques, symboliques, narratives, géométriques, algébriques, interpellatrices, révélatrices, auto réflexives et méta-discursives. J'aimerais appeler cet ensemble « les qualités miroiriques», pour emprunter un terme à Duchamp , puisqu' elles concernent les qualités du miroir. J'ai cru pouvoir analyser leur fonctionnement dans les œuvres, à l’appui de celles de Pistoletto, et en gardant le souci de les rapporter à un récepteur qui en jouit. Je suis donc allée à la recherche de cette métaphore courante qui prétend que l’art reflète la vie dans la conviction qu'un objet ou une expérience artistiques n'existent pour ce récepteur que quand ils lui renvoient des images et des possibilités de lui-même et de son monde; et ceci dans la conviction que, par exemple, son expérience du double est moins une expérience de reproduction qu'une expérience qui le nourrit de lui-même. Les qualités miroiriques multiples des œuvres équivalent à leur potentiel mobilisateur; elles m'ont amenée à rechercher les formes de vitalité qui se dessinent à l’intérieur de cette mobilisation. Autrement dit, à reprendre le débat, qui semblerait plutôt épuisé, sur les rapports entre l’art et la vie. Mais ce débat n'a pu m'intéresser que dans la mesure où le point de vue des qualités miroiriques déplaçait son paradigme duel: celui sur lequel se profilent des oppositions vicieuses comme subjectif/objectif, expressionnisme / inexpressionnisme, expression / engagement social, contemplation / participation, choses / images, bidimensionnel / tridimensionnel, autonomie / utilité, formaliste / référentiel et d'autres qui leur sont proches. Il n'y a pas d'art ou la vie ne soit pas inscrite; ce qui change sont les points de vue, les lectures et le genre de «vie» recherchée et / ou oblitérée. Comme on le verra, c'est encore l’œuvre de Pistoletto qui m'en a fourni les meilleurs prétextes. Celle-ci inclut des initiatives aussi disparates que des objets, des «actions» ou des textes écrits. Son œuvre écrite est à la fois informative, littéraire, programmatique et plastique, ce qui ne va pas sans poser quelques problèmes dans l’approche interprétative. Les révélations apportées par les miroirs littéraux et métaphoriques concernent aussi, entre autres, les problèmes de l’encadrement, de la peinture, de la représentation, du sujet, de l’auto-reconnaissance et de la participation à l’œuvre.

This thesis focuses on 3D computer graphics and the continuous maximisation of rendering quality and performance. Its main focus is the critical analysis of numerous real-time rendering algorithms and the construction of an empirically derived system for the high-speed rendering of shader-based special effects, lighting effects, shadows, reflection and refraction, post-processing effects and the processing of physics. This critical analysis allows us to assess the relationship between rendering quality and performance. It also allows for the isolation of key algorithmic weaknesses and possible bottleneck areas. Using this performance data, gathered during the analysis of various rendering algorithms, we are able to define a selection engine to control the real-time cycling of rendering algorithms and special effects groupings based on environmental conditions. Furthermore, as a proof of concept, to balance Central Processing Unit (CPU) and Graphic Processing Unit (GPU) load for and increased speed of execution, our selection system unifies the GPU and CPU as a single computational unit for physics processing and environmental mapping. This parallel computing system enables the CPU to process cube mapping computations while the GPU can be tasked with calculations traditionally handled solely by the CPU. All analysed and benchmarked algorithms were implemented as part of a modular rendering engine. This engine offers conventional first-person perspective input control, mesh loading and support for shader model 4.0 shaders (via Microsoft’s High Level Shader Language) for effects such as high dynamic range rendering (HDR), dynamic ambient lighting, volumetric fog, specular reflections, reflective and refractive water, realistic physics, particle effects, etc. The test engine also supports the dynamic placement, movement and elimination of light sources, meshes and spatial geometry. Critical analysis was performed via scripted camera movement and object and light source additions – done not only to ensure consistent testing, but also to ease future validation and replication of results. This provided us with a scalable interactive testing environment as well as a complete solution for the rendering of computationally intensive 3D environments. As a full-fledged game engine, our rendering engine is amenable to first- and third-person shooter games, role playing games and 3D immersive environments. Evaluation criteria (identified to access the relationship between rendering quality and performance), as mentioned, allows us to effectively cycle algorithms based on empirical results and to distribute specific processing (cube mapping and physics processing) between the CPU and GPU, a unification that ensures the following: nearby effects are always of high-quality (where computational resources are available), distant effects are, under certain conditions, rendered at a lower quality and the frames per second rendering performance is always maximised. The implication of our work is clear: unifying the CPU and GPU and dynamically cycling through the most appropriate algorithms based on ever-changing environmental conditions allow for maximised rendering quality and performance and shows that it is possible to render high-quality visual effects with realism, without overburdening scarce computational resources. Immersive rendering approaches used in conjunction with AI subsystems, game networking and logic, physics processing and other special effects (such as post-processing shader effects) are immensely processor intensive and can only be successfully implemented on high-end hardware. Only by cycling and distributing algorithms based on environmental conditions and through the exploitation of algorithmic strengths can high-quality real-time special effects and highly accurate calculations become as common as texture mapping. Furthermore, in a gaming context, players often spend an inordinate amount of time fine-tuning their graphics settings to achieve the perfect balance between rendering quality and frames-per-second performance. Using this system, however, ensures that performance vs. quality is always optimised, not only for the game as a whole but also for the current scene being rendered – some scenes might, for example, require more computational power than others, resulting in noticeable slowdowns, slowdowns not experienced thanks to our system’s dynamic cycling of rendering algorithms and its proof of concept unification of the CPU and GPU.
Thesis (PhD)--University of Pretoria, 2012.
Computer Science
unrestricted