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.

abstract: Non-line-of-sight (NLOS) imaging of objects not visible to either the camera or illumina- tion source is a challenging task with vital applications including surveillance and robotics. Recent NLOS reconstruction advances have been achieved using time-resolved measure- ments. Acquiring these time-resolved measurements requires expensive and specialized detectors and laser sources. In work proposes a data-driven approach for NLOS 3D local- ization requiring only a conventional camera and projector. The localisation is performed using a voxelisation and a regression problem. Accuracy of greater than 90% is achieved in localizing a NLOS object to a 5cm × 5cm × 5cm volume in real data. By adopting the regression approach an object of width 10cm to localised to approximately 1.5cm. To generalize to line-of-sight (LOS) scenes with non-planar surfaces, an adaptive lighting al- gorithm is adopted. This algorithm, based on radiosity, identifies and illuminates scene patches in the LOS which most contribute to the NLOS light paths, and can factor in sys- tem power constraints. Improvements ranging from 6%-15% in accuracy with a non-planar LOS wall using adaptive lighting is reported, demonstrating the advantage of combining the physics of light transport with active illumination for data-driven NLOS imaging. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

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.

University, Diss., 2000--Dortmund. / Dateiformat: PDF.

University, Diss., 2000--Dortmund. / Dateiformat: PDF.

Pour réduire la consommation énergétique des bâtiments, les systèmes de chauffage agissant par rayonnement semblent particulièrement intéressants puisqu'ils ne nécessitent pas de chauffer l'air de la pièce pour que leur action soit perçue (moins d'énergie dépensée et moins de déperditions) et qu'jls permettent une meilleure réactivité au mode de vie des utilisateurs. De plus, des expériences réalisées au MIT ont montré que nous préférons un air frais et des murs chauds plutôt que le contraire, ce qui milite en paveur du chauffage par rayonnement. L'objectif de ce travail est de développer un outil permettant de paire le lien entre le rayonnement échangé entre un occupant et son environnement et le confort qu'il exprime vis-a- vis de celui-ci. L'étude des transferts radiatifs dans l'habitat peut se ramener a la résolution de l'équation des radiosités. Celle-ci nécessite l'évaluation de couplages géométriques entre les éléments de la scène appelés facteurs de forme. Leur obtention est particulièrement ardue, notamment lorsqu'il s'agit de tenir compte d'éventuelles obstructions. Une comparaison des méthodes numériques disponibles pour cela est proposée. Outre l'évaluation de ces facteurs, le système a résoudre est très lourd, puisque chaque surface interagit, le plus souvent, avec toutes les autres et que le nombre de nœuds mis en jeu dans la description d'une scène complexe est important. Nous présentons une méthode de résolution qui raffine le maillage d'une scène tout en construisant simultanément une représentation a différentes échelles des facteurs de forme entre ses éléments, dans le but de ne pas calculer tous les échanges a la résolution la plus fine. Elle permet ainsi de réduire considérablement le temps de calcul et rend son utilisation possible en bureau d'étude.une fois que les transferts radiatifs entre un individu, la source de chauffage et différents éléments de l'environnement sont connus, le modèle de confort de Fanger est mis en oeuvre pour déterminer si les configurations envisagées sont confortables ou non, au regard des normes en vigueur dans le bâtiment. Ainsi, nous avons pu déterminer quels types d'appareils de chauffage sont les plus susceptibles d'apporter du confort, dans diverses situations, et sans accroitre la puissance consommée. / In order to reduce building's energy consumption, radiant heater seems particularly attractives because they didn't require to heat the air of the room to be perceived (less energy spent and less losses), and because they provide a better reactivity to users life rythmes. Moreover, experiences of the MIT showed that we prefer a fresh ai with warm wall rather than the opposite. The goal of the work is to develop a tool to study the link between the radiant energy exchange by an occupant with his environment and the thermal comfort express under some hypothesis, radiative beat transfers can be idealized by the radiosity equation. This one needs the evaluation of geometrics couplings between the elements of the scene called form factors or view factors. It's generally hard to get them, especially when there are obstructions. A comparison of existing numerical methods is proposed. beyond the evaluation of those factors, the algebraic system is heavy to solve because each surface interact, usually, with all the others and because the number of nodes required for the description of a complexe scene is important. We present a resolution method which refine the mesh of the scene while constructing a multi scale representation of form factors between its elements, in order to don't have to compute all the transfers at the finest resolution. This drastically reduce the computation time and allow to use this method in a industrial development process.When the radiative transfers between the occupant, heaters and differents elements of the environment are known, the thermal comfort model of fanger is used to determine if the considered env!ronments are confortable or not, according to international standards. This way, we could find which type of heaters are the most subject to provide thermal comfort without increasing energy consumption.

Die vorliegende Arbeit beschäftigt sich mit dem schnellen Lösen von Randintegralgleichungen auf polygonalen oder polygonal approximierten Oberflächen basierend auf Wavelet-Galerkinverfahren. Ein besonderes Augenmerk gilt dabei der speziellen Problematik der diffusen Beleuchtungsgleichung. Während traditionelle Ansätze für Randintegralgleichungen zu vollbesetzten Systemmatrizen und damit zu einem quadratischen Aufwand führen, nutzen Waveletverfahren spezielle Multiskalenbasen, die eine Kompression der Systemmatrix zu einer dünnbesetzten Matrix und damit einen linear-logarithmischen Aufwand ermöglichen. In der Arbeit wird das H^2-Waveletverfahren als effiziente Umsetzung der Waveletverfahren auf polygonal approximierten Oberflächen basierend auf den Tausch-White-Wavelets entwickelt. Es stellt eine Kombination aus H^2-Techniken, bekannt von dem Gebiet der hierarchischen Matrizen, und rekusiven Wavelettechniken dar. Zum besseren Verständnis werden dazu innerhalb der Arbeit in eigenen Kapiteln das Wichtigste zu den Tausch-White-Wavelets, zu dem allgemeinen Waveletverfahren und der Waveletkompression sowie zu den H^2-Matrizen präsentiert, bevor das H^2-Waveletverfahren detailiert hergeleitet und der entsprechende linear-logarithmische Aufwand bewiesen wird. Der zweite Schwerpunkt der Arbeit liegt auf der diffusen Beleuchtungsgleichung. Die in ihr enthaltene Sichbarkeitsproblematik verhindertete bis jetzt die Anwendung moderner schneller Verfahren und die Reduktion der Kosten auf linear-logarithmischen Aufwand. Mit Hilfe der in dieser Arbeit neu entwickelten speziell auf die diffuse Beleuchtungsgleichung angepassten Waveletkompression ist es jedoch möglich ein dünnbesetzte Systemmatrix aufzustellen und im Bereich des Speichers den gewünschten linear-logarithmischen Aufwand zu erreichen. Alle in der Arbeit entwickelten Algorithmen sind detailiert dargestellt und mit numerische Ergebnissen unterlegt.

Thesis (M.S.)--State University of New York at Binghamton, Department of Computer Science, Thomas J. Watson School of Engineering and Applied Science, 2007. / Includes bibliographical references.

Techn. University, Diss., 2004--Braunschweig.

The characteristics of irregular algorithms make a parallel implementation difficult, especially for PC clusters or clusters of SMPs. These characteristics may include an unpredictable access behavior to dynamically changing data structures or strong irregular coupling of computations. Problems are an unknown load distribution and expensive irregular communication patterns for data accesses and redistributions. Thus the parallel implementation of irregular algorithms on distributed memory machines and clusters requires a special organizational mechanism for a dynamic load balance while keeping the communication and administration overhead low. We propose task pool teams for implementing irregular algorithms on clusters of PCs or SMPs. A task pool team combines multithreaded programming using task pools on single nodes with explicit message passing between different nodes. The dynamic load balance mechanism of task pools is generalized to a dynamic load balance scheme for all distributed nodes. We have implemented and compared several versions for task pool teams. As application example, we use the hierarchical radiosity algorithm, which is based on dynamically growing quadtree data structures annotated by varying interaction lists expressing the irregular coupling between the quadtrees. Experiments are performed on a PC cluster and a cluster of SMPs.