L'utilisation d'algorithmes de vision permettrait d'élargir le domaine d'application des systèmes d'aide à la conduite à d'autres situations telles que : les scènes urbaines ou les conditions météorologiques dégradées. À cette fin, trois nouvelles applications sont étudiées dans cette thèse pour la pluie et les feux tricolores. La pluie est la condition météorologique dégradée la plus fréquente. Nous comparons les modèles physiques et photométriques existants pour la pluie et les gouttes de pluie. Lors d'une conduite en temps de pluie de jour, les gouttes sur le pare-brise diminuent considérablement la visibilité du conducteur. Lorsqu'elles sont vue par une camera embarquée standard celles-ci apparaissent défocalisées. Ainsi, nous proposons de détecter ces gouttes hors-focus en utilisant soit une approche par manque de gradients soit par l'évaluation locale du flou. Lors d'une conduite de nuit sous la pluie, ce sont les phares qui paradoxalement diminuent la visibilité car leur lumière est réfléchie par les gouttes vers le conducteur. Nous appuyant sur la conception d'un simulateur physique, nous proposons un éclairage adaptatif qui illuminerait la scène sans éclairer les gouttes qui tombent. Les résultats de notre simulateur et le premier prototype construit montre que l'idée avancée pourrait efficacement améliorer la visibilité générale d'une scène. D'autre part, nous étudions la détection et le suivi de gouttes de pluie à grande vitesse. Les feux tricolores ont un rôle crucial dans la compréhension des scènes urbaines. Bien qu'il existe déjà des systèmes de détection de feux tricolores, les algorithmes actuels ne fonctionnent que dans des conditions simples. Ainsi, nous avons développé un algorithme de détection de feux tricolores qui utilise une détection en niveau de gris des spots lumineux et une classification par reconnaissance de modèle. L'approche ainsi conçue est assez flexible pour détecter différents types de feux tricolores même avec une camera à faible dynamique. Notre proposition a été évaluée sur des séquences acquises en France, Chine et Suisse. / Vision algorithms can be used to expand the working range of the assistance systems so as to deal with urban scenes or degraded weathers. To this end, three novel applications are investigated in this thesis for both rain and traffic lights. Rain is the most frequent degraded weather condition. We review the various physics and photometry models for rain and raindrops, and highlight some of the misuses. When driving in daytime the raindrops on the windscreen lower the driver visibility. For standard on-board camera these drops appear as unfocused. Hence, we investigate the detection of unfocused raindrops using blur maps or lack of gradients with photometry. For nightime driving in rain, the headlights paradoxically reduce the visibility due to light reflected off of raindrops back toward the driver. Relying on a physic-based simulator, we propose to build an illumination device that would illuminate the scene without shining the falling particles. The performance of the simulator and a proof-of-concept prototype sustain that our idea can efficiently improve the overall scene visibility. Fast reactive drops detection and tracking is also investigated.To deal with urban scenes, traffic lights play a key role. Though traffic light recognition was attempted in the past, the existing algorithms can't handle complex scenarios. Hence, we have developed a traffic light recognition algorithm that uses a grayscale spot light detection and a template matching classification. Our approach is modular and capable of detecting various kind of traffic lights even when using a low-dynamic camera. We have evaluated our algorithm on sequences from France, China and Switzerland.

La simulation d'éclairage est un processus qui s'avère plus complexe (temps de calcul, coût mémoire, mise en œuvre complexe) aussi bien pour les matériaux brillants que pour les matériaux lambertiens ou spéculaires. Afin d'éviter le calcul coûteux de certains termes de l'équation de luminance (convolution entre la fonction de réflexion des matériaux et la distribution de luminance de l'environnement), nous proposons une nouvelle structure de données appelée Source Surfacique Équivalente (SSE). L'utilisation de cette structure de données nécessite le pré-calcul puis la modélisation du comportement des matériaux soumis à divers types de sources lumineuses (positions, étendues). L'exploitation d'algorithmes génétiques nous permet de déterminer les paramètres des modèles de BRDF, en introduisant une première source d'approximation. L'approche de simulation d'éclairage utilisée est basée sur un cache de luminance. Ce dernier consiste à stocker l'éclairement incident sous forme de SSE en des points appelés enregistrements. Durant la simulation d'éclairage, l'environnement lumineux doit également être assimilé à un ensemble de sources surfaciques équivalentes (en chaque enregistrement) qu'il convient de définir de manière dynamique. Cette phase constitue une deuxième source d'erreur. Toutefois, l'incertitude globale ne se réduit pas au cumul des approximations réalisées à chaque étape. Les comparatives réalisées prouvent, au contraire, que l'approche des Sources Surfaciques Équivalentes est particulièrement intéressante pour des matériaux rugueux ou pour les matériaux très brillants placés dans des environnements relativement uniformes. L'utilisation de SSE a permis de réduire considérablement à la fois le coût mémoire et le temps de calcul. Une fois que les SSE sont calculés en chaque enregistrement et pour un certain nombre de points de vue, nous proposons une nouvelle méthode de visualisation interactive exploitant les performances des GPU (carte graphique) et s'avérant plus rapide que les méthodes existantes. Enfin nous traiterons le cas où les grandeurs photométriques sont spectrales, ce qui est très important lorsqu'il s'agit de réaliser des simulations d'éclairage précises. Nous montrerons comment adapter les zones d'influence des enregistrements en fonction des gradients de luminance et de la géométrie autour des enregistrements. / Radiance caching methods have proven efficient for global illumination. Their goal is to compute precisely illumination values (incident radiance or irradiance) at a reasonable number of points lying on the scene surfaces. These points, called records, are stored in a cache used for estimating illumination of other points in the scene. Unfortunately, with records lying on glossy surfaces, the irradiance value alone is not sufficient to evaluate the reflected radiance; each record should also store the incident radiance for all incident directions. Memory storage can be reduced with projection techniques using spherical harmonics or other basis functions. These techniques provide good results with low shininess BRDFs. However, they get impractical for shininess of even moderate value since the number of projection coefficients increase drastically. In this paper, we propose a new radiance caching method, that handles highly glossy surfaces, while requiring a low memory storage. Each cache record stores a coarse representation of the incident illumination thanks to a new data structure called Equivalent Area light Sources (EAS), capable of handling fuzzy mirror surfaces. In addition, our method proposes a new simplification of the interpolation process since it avoids the need for expressing and evaluating complex gradients. Moreover, we propose a new GPU based visualisation method which exploits these EAS data structure. Thus, interactive rendering is done faster than existing methods. Finally, physical ligting simulations need to manipulate spectral physical quantities. We demonstrate in our work how these quantities can be handle with our technic by adapting the record influence zone depending on the radiance gradients and the geometry around the records.

This master’s thesis deals with the construction design of microscope episcopic LED illumination source and subsequent functional sample realization. Illumination source is compatible with industrial microscope Nikon Eclipse LV150 and designed as a replacement for halogen light source. Way of collecting light is chosen with respect to search analysis results and collector optical element and LED is selected with respect to the analysis of the episcopic illuminator. Two construction designs are designed with respect to the results of photometric analyzes. Optimal design is realized and compared with used lighting sources – halogen and xenon.

This thesis deals with the estimation of global illumination of a~scene. Global illumination is expressed as a~physical simulation in connection with illumination methods used in current computer graphics. In the practical part there is expressed an implementation of global illumination estimation using photon maps.

Le romantisme français est hanté par la fête de nuit, thème obsédant qui s’incarne dans les productions poétiques, dramatiques et narratives, majeures comme mineures, dès les libations de Smarra ou les Démons de la nuit de Charles Nodier. À partir de ce constat, cette thèse déploie et analyse le choix du cadre nocturne pour écrire la fête entre 1821 et 1856. L’étude du motif permet de rouvrir l’analyse de la nuit romantique pour montrer que ce thème livre, non pas une, mais plusieurs poétiques dont certaines se révèlent ancrées dans la modernité. La fête de nuit intègre tout d’abord l’imaginaire nocturne « traditionnel » du romantisme, lui-même hérité de représentations anciennes de la nuit, noire et claire. Or, ces nuits fantastiques, oniriques et lyriques ne sont pas toutes les nuits romantiques. Alors que la première moitié du XIXe siècle invente la nuit blanche, la littérature se fait la chambre d’échos bruyante de nuits parisiennes agitées, reflets d’une époque qui annonce les mythes de la ville-lumière et de la fête impériale. Ces images, qui circulent entre « littérature panoramique » et corpus romantique, trahissent la passion du siècle pour le spectaculaire. La fête de nuit transforme le quotidien en spectacle. Les fictions esquissent en outre des types de la fête de nuit parisienne souvent proches de la figure de l’auteur romantique, habituellement présenté comme un mélancolique solitaire. Porteuse de contrastes entre lumière et nuit, vie et mort, la fête de nuit apparaît finalement comme une posture existentielle et scripturaire adoptée par l’homme romantique qui entend se révolter contre la nuit noire, avec les feux et les fantaisies de la nuit blanche. / As a writing pattern, night feasts haunt French Romanticism since Nodier’s Smarra ou les Démons de la nuit (1821). The motif appears in poetic, dramatic and narrative works, in major as well as in minor productions. This thesis answers the following question : why is the night the place to write feasts in French Romanticism, between 1821 and 1856 ? In this way, this dissertation reopens the analysis of the Romantic night and shows that this theme provides not once but various poetics, some of them announcing modernity. Certainly, night feasts are part of a Romantic “classical” nocturnal imagination, inherited from ancient traditions. But fantastic, dreamlike and lyrical hues are not the only colors of the Romantic nights. In fact, thanks to the invention of night life in the early 19th century, Romantic works reflect restless Parisian nights, during a period which discovers night leisure activities, forecasting the myth of City of Light and the entertainment’s industry blooming during the Second Empire area. The images of the night feast, which circulate between “panoramic literature” and Romantic literature, reveal the century’s burning passion for sight. These nocturnal festivities transform everyday life into a show. Furthermore, fictions are brimming with archetypal characters inhabiting the Parisian festive nights, themselves often suggestive of the Romantic figure of the author, usually depicted as a melancholic loner. Based on contrasts, between light and darkness, life and death, the night feast is also an existential and creative pattern for Romantic authors who are using the night life and their lights as a way to rise up against the dark night.

Roundabout installations are becoming common practice among DOTs and other local governments due to their superior safety attributes compared to other conventional at-grade intersections, especially stop-control and uncontrolled intersections. Current U.S. national guidelines for roundabout illumination recommend systematic illumination for all roundabouts. This recommendation might become a potential hindrance to desired widespread installations due to implied financial costs, especially in rural areas because the competing stop-control and uncontrolled intersections can be kept unlit. Interestingly rural roundabouts in most countries around the world are not illuminated as indicated by a recent survey of international roundabout illumination policies and standards from 45 countries. Also, review of intersection safety literature does not identify any publication that supports a systematic illumination policy of U.S. roundabouts. In fact, despite this recommendation there is no quantitative research on influence of illumination levels on nighttime safety at roundabouts and little on conventional intersections. Conversely, the literature shows a significant number of published studies which have indicated that currently recommended illumination levels on roadways can be reduced without compromising nighttime safety. This dissertation evaluates the link between roundabout crashes and different illumination levels. At the beginning of this dissertation research, there was no available repository of quantitative intersection illumination levels which could be used in highway safety research. Also, existing protocols for measurement require expensive light meters and are extremely time consuming to follow, making them impractical to use to study a large number of intersections. Consequently, this dissertation first evaluates the relationship with the best available data. The best available intersection illumination data was obtained from the Minnesota data contained in the Highway Safety Information System (HSIS). Minnesota crash and illumination data from 2003 to 2010 were analyzed. This illumination data was a qualitative description of intersection illuminating schemes and/or luminaire arrangement. Therefore, this dissertation also developed a cost-effective, accurate, and rapid method for measurement of quantitative intersection illumination data, and applied the developed protocol to a case study in Georgia. The measured intersection illumination was analyzed together with crash data obtained from GDOT for 2009 to 2014. The results of a naive analysis on the best available data indicated among other findings that the presence of lighting can provide approximately 61 percent lower total nighttime crash rate compared to the unlit condition. Also, providing illumination to the roundabout circle alone can yield about 80 percent of the benefits (55 percent reduction from unlit condition) of illuminating both the roundabout circle and approaches (66 percent reduction from unlit condition). Field test results for the camera calibration indicate that the average intersection illuminance derived from the protocol is within 4 percent difference of the actual average intersection illumination estimated from following the existing protocols. Next, despite limited roundabout data and potential issues of selection bias which could not be addressed in this dissertation, a cautious roundabout illumination specific crash modification factor was estimated with a negative binomial regression model. The model results showed that an increase of 1 lux in average roundabout illuminance will result in a 4.72 percent reduction in expected number nighttime crashes. The results of this work are useful in creating a sound framework for DOTs and other transportation agencies to determine the most appropriate level of illumination for roundabouts. This study also makes a number of significant contributions to highway safety research. First, this work is the first quantitative study on the impact of illumination on safety at roundabouts. The status-quo for highway safety research regarding the impacts of illumination had been to treat road lighting as a binary (Lit/Unlit) variable. However, even in most places without purposely-built road lighting there is usually ambient lighting from abutting facilities such as a gas stations or a store. Second, this dissertation is the first documented application of the photographic method to roundabouts. It is also the first documented application of the photographic method’s camera specific constant calibration approach to transportation field measurements. Previous documented application of the photographic method to transportation field measurements used an exposure specific calibration approach. Unlike the camera specific constant calibration approach, the exposure specific approach is rigid and field measurements must always be done at the exposure settings used in calibrating the camera. Thirdly, this work demonstrates the first developed procedure to developing uniformity (contour) plots from the photographic method. Next, this work can serve as the basis for initial efforts to create an illumination specific quantitative crash modification factor. Currently, the Highway Safety Manual is lacking in this important safety parameter. Last, but not the least this work offers procedures for collecting luminance data from the field and also documents a database of intersection illumination levels and intersection characteristics which can be used by future research.

Failures of high mast illumination poles (HMIP) around the US have raised the concerns of officials because of their location close to areas with important human activity. Previous research, conducted at the University of Texas proved that those failures were fatigue type failures and that cracking initiated at the shaft to baseplate connection, specifically at the bends of the shaft. However, no research has been conducted on the remaining fatigue life of poles after they have been in service. This thesis investigates the remaining fatigue life of a pole, removed from service after severe cracking has been observed on it, via laboratory testing. Moreover, nondestructive and destructive testing procedures were implemented to investigate the initiation and evolution of fatigue cracks. The results validated the procedures for the in-situ validation of the remaining fatigue life of those poles. Last, the destructive test results enhanced the arguments that initial cracking at the toe of the weld at the shaft to baseplate connection is a result of the galvanizing process. / text

Global illumination algorithms are used to render photorealistic images of 3D scenes taking into account both direct lighting from the light source and light reflected from other surfaces in the scene. Algorithms based on computing radiosity were among the first to be used to calculate indirect lighting, although they make assumptions that work only for diffusely reflecting surfaces. The classic radiosity approach divides a scene into multiple patches and generates a linear system of equations which, when solved, gives the values for the radiosity leaving each patch. This process can require extensive calculations and is therefore very slow. An alternative to solving a large system of equations is to use a Monte Carlo method of random sampling. In this approach, a large number of rays are shot from each patch into its surroundings and the irradiance values obtained from these rays are averaged to obtain a close approximation to the real value. <br /><br /> This thesis proposes the use of a Monte Carlo method to generate radiosity texture maps on graphics hardware. By storing the radiosity values in textures, they are immediately available for rendering, making this algorithm useful for interactive implementations. We have built a framework to run this algorithm and using current graphics cards (NV6800 or higher) it is possible to execute it almost interactively for simple scenes and within relatively low times for more complex scenes.

Global illumination is an important area of computer graphics, having direct applications in architectural visualization, lighting design and entertainment. Indirect illumination effects such as soft shadows, color bleeding, caustics and glossy reflections provide essential visual information about the interaction of different regions of the environment. Global illumination is a research area that deals with these illumination effects. Interactivity is also a desirable feature for many computer graphics applications, especially with unrestricted manipulation of the environment and lighting conditions. However, the design of methods that can handle both unrestricted interactivity and global illumination effects on environments of reasonable complexity is still an open challenge. <br /><br /> We present a new formulation of the light transport equation, called <em>pencil light transport</em>, that makes progress towards this goal by exploiting graphics hardware rendering features. The proposed method performs the transport of radiance over a scene using sets of pencils. A pencil object consists of a center of projection and some associated directional data. We show that performing the radiance transport using pencils is suitable for implementation on current graphics hardware. The new algorithm exploits optimized operations available in the graphics hardware architecture, such as pinhole camera rendering of opaque triangles and texture mapping. We show how the light transport equation can be reformulated as a sequence of light transports between pencils and define a new light transport operator, called the <em>pencil light transport operator</em>, that is used to transfer radiance between sets of pencils.

The purpose of this project was to test and implement recent research of polarization and scatter properties that suggest using a cross polarization imaging system to reduce glare artifacts. In particular, the use of this research is to improve the machine vision of apple quality detection in the food industry. The automated measurement system was implemented by acquiring pictures at different angles and different polarization states of apples. The opto-mechanics, system integration, synchronization and data collection are controlled with LabVIEW.