Programmable Image-Based Light Capture for Previsualization

Previsualization is a class of techniques for creating approximate previews of a movie sequence in order to visualize a scene prior to shooting it on the set. Often these techniques are used to convey the artistic direction of the story in terms of cinematic elements, such as camera movement, angle, lighting, dialogue, and character motion. Essentially, a movie director uses previsualization (previs) to convey movie visuals as he sees them in his minds-eye . Traditional methods for previs include hand-drawn sketches, Storyboards, scaled models, and photographs, which are created by artists to convey how a scene or character might look or move. A recent trend has been to use 3D graphics applications such as video game engines to perform previs, which is called 3D previs. This type of previs is generally used prior to shooting a scene in order to choreograph camera or character movements. To visualize a scene while being recorded on-set, directors and cinematographers use a technique called On-set previs, which provides a real-time view with little to no processing. Other types of previs, such as Technical previs, emphasize accurately capturing scene properties but lack any interactive manipulation and are usually employed by visual effects crews and not for cinematographers or directors. This dissertation\u27s focus is on creating a new method for interactive visualization that will automatically capture the on-set lighting and provide interactive manipulation of cinematic elements to facilitate the movie maker\u27s artistic expression, validate cinematic choices, and provide guidance to production crews. Our method will overcome the drawbacks of the all previous previs methods by combining photorealistic rendering with accurately captured scene details, which is interactively displayed on a mobile capture and rendering platform. This dissertation describes a new hardware and software previs framework that enables interactive visualization of on-set post-production elements. A three-tiered framework, which is the main contribution of this dissertation is; 1) a novel programmable camera architecture that provides programmability to low-level features and a visual programming interface, 2) new algorithms that analyzes and decomposes the scene photometrically, and 3) a previs interface that leverages the previous to perform interactive rendering and manipulation of the photometric and computer generated elements. For this dissertation we implemented a programmable camera with a novel visual programming interface. We developed the photometric theory and implementation of our novel relighting technique called Symmetric lighting, which can be used to relight a scene with multiple illuminants with respect to color, intensity and location on our programmable camera. We analyzed the performance of Symmetric lighting on synthetic and real scenes to evaluate the benefits and limitations with respect to the reflectance composition of the scene and the number and color of lights within the scene. We found that, since our method is based on a Lambertian reflectance assumption, our method works well under this assumption but that scenes with high amounts of specular reflections can have higher errors in terms of relighting accuracy and additional steps are required to mitigate this limitation. Also, scenes which contain lights whose colors are a too similar can lead to degenerate cases in terms of relighting. Despite these limitations, an important contribution of our work is that Symmetric lighting can also be leveraged as a solution for performing multi-illuminant white balancing and light color estimation within a scene with multiple illuminants without limits on the color range or number of lights. We compared our method to other white balance methods and show that our method is superior when at least one of the light colors is known a priori

Realtime image noise reduction FPGA implementation with edge detection

The purpose of this dissertation was to develop and implement, in a Field Programmable Gate Array (FPGA), a noise reduction algorithm for real-time sensor acquired images. A Moving Average filter was chosen due to its fulfillment of a low demanding computational expenditure nature, speed, good precision and low to medium hardware resources utilization. The technique is simple to implement, however, if all pixels are indiscriminately filtered, the result will be a blurry image which is undesirable. Since human eye is more sensitive to contrasts, a technique was introduced to preserve sharp contour transitions which, in the author’s opinion, is the dissertation contribution. Synthetic and real images were tested. Synthetic, composed both with sharp and soft tone transitions, were generated with a developed algorithm, while real images were captured with an 8-kbit (8192 shades) high resolution sensor scaled up to 10 × 103 shades. A least-squares polynomial data smoothing filter, Savitzky-Golay, was used as comparison. It can be adjusted using 3 degrees of freedom ─ the window frame length which varies the filtering relation size between pixels’ neighborhood, the derivative order, which varies the curviness and the polynomial coefficients which change the adaptability of the curve. Moving Average filter only permits one degree of freedom, the window frame length. Tests revealed promising results with 2 and 4ℎ polynomial orders. Higher qualitative results were achieved with Savitzky-Golay’s better signal characteristics preservation, especially at high frequencies. FPGA algorithms were implemented in 64-bit integer registers serving two purposes: increase precision, hence, reducing the error comparatively as if it were done in floating-point registers; accommodate the registers’ growing cumulative multiplications. Results were then compared with MATLAB’s double precision 64-bit floating-point computations to verify the error difference between both. Used comparison parameters were Mean Squared Error, Signalto-Noise Ratio and Similarity coefficient.O objetivo desta dissertação foi desenvolver e implementar, em FPGA, um algoritmo de redução de ruído para imagens adquiridas em tempo real. Optou-se por um filtro de Média Deslizante por não exigir uma elevada complexidade computacional, ser rápido, ter boa precisão e requerer moderada utilização de recursos. A técnica é simples, mas se abordada como filtragem monotónica, o resultado é uma indesejável imagem desfocada. Dado o olho humano ser mais sensível ao contraste, introduziu-se uma técnica para preservar os contornos que, na opinião do autor, é a sua principal contribuição. Utilizaram-se imagens sintéticas e reais nos testes. As sintéticas, compostas por fortes e suaves contrastes foram geradas por um algoritmo desenvolvido. As reais foram capturadas com um sensor de alta resolução de 8-kbit (8192 tons) e escalonadas a 10 × 103 tons. Um filtro com suavização polinomial de mínimos quadrados, SavitzkyGolay, foi usado como comparação. Possui 3 graus de liberdade: o tamanho da janela, que varia o tamanho da relação de filtragem entre os pixels vizinhos; a ordem da derivada, que varia a curvatura do filtro e os coeficientes polinomiais, que variam a adaptabilidade da curva aos pontos a suavizar. O filtro de Média Deslizante é apenas ajustável no tamanho da janela. Os testes revelaram-se promissores nas 2ª e 4ª ordens polinomiais. Obtiveram-se resultados qualitativos com o filtro Savitzky-Golay que detém melhores características na preservação do sinal, especialmente em altas frequências. Os algoritmos em FPGA foram implementados em registos de vírgula fixa de 64-bits, servindo dois propósitos: aumentar a precisão, reduzindo o erro comparativamente ao terem sido em vírgula flutuante; acomodar o efeito cumulativo das multiplicações. Os resultados foram comparados com os cálculos de 64-bits obtidos pelo MATLAB para verificar a diferença de erro entre ambos. Os parâmetros de medida foram MSE, SNR e coeficiente de Semelhança

Lichttransportsimulation auf Spezialhardware

It cannot be denied that the developments in computer hardware and in computer algorithms strongly influence each other, with new instructions added to help with video processing, encryption, and in many other areas. At the same time, the current cap on single threaded performance and wide availability of multi-threaded processors has increased the focus on parallel algorithms. Both influences are extremely prominent in computer graphics, where the gaming and movie industries always strive for the best possible performance on the current, as well as future, hardware. In this thesis we examine the hardware-algorithm synergies in the context of ray tracing and Monte-Carlo algorithms. First, we focus on the very basic element of all such algorithms - the casting of rays through a scene, and propose a dedicated hardware unit to accelerate this common operation. Then, we examine existing and novel implementations of many Monte-Carlo rendering algorithms on massively parallel hardware, as full hardware utilization is essential for peak performance. Lastly, we present an algorithm for tackling complex interreflections of glossy materials, which is designed to utilize both powerful processing units present in almost all current computers: the Centeral Processing Unit (CPU) and the Graphics Processing Unit (GPU). These three pieces combined show that it is always important to look at hardware-algorithm mapping on all levels of abstraction: instruction, processor, and machine.Zweifelsohne beeinflussen sich Computerhardware und Computeralgorithmen gegenseitig in ihrer Entwicklung: Prozessoren bekommen neue Instruktionen, um zum Beispiel Videoverarbeitung, Verschlüsselung oder andere Anwendungen zu beschleunigen. Gleichzeitig verstärkt sich der Fokus auf parallele Algorithmen, bedingt durch die limitierte Leistung von für einzelne Threads und die inzwischen breite Verfügbarkeit von multi-threaded Prozessoren. Beide Einflüsse sind im Grafikbereich besonders stark , wo es z.B. für die Spiele- und Filmindustrie wichtig ist, die bestmögliche Leistung zu erreichen, sowohl auf derzeitiger und zukünftiger Hardware. In Rahmen dieser Arbeit untersuchen wir die Synergie von Hardware und Algorithmen anhand von Ray-Tracing- und Monte-Carlo-Algorithmen. Zuerst betrachten wir einen grundlegenden Hardware-Bausteins für alle diese Algorithmen, die Strahlenverfolgung in einer Szene, und präsentieren eine spezielle Hardware-Einheit zur deren Beschleunigung. Anschließend untersuchen wir existierende und neue Implementierungen verschiedener MonteCarlo-Algorithmen auf massiv-paralleler Hardware, wobei die maximale Auslastung der Hardware im Fokus steht. Abschließend stellen wir dann einen Algorithmus zur Berechnung von komplexen Beleuchtungseffekten bei glänzenden Materialien vor, der versucht, die heute fast überall vorhandene Kombination aus Hauptprozessor (CPU) und Grafikprozessor (GPU) optimal auszunutzen. Zusammen zeigen diese drei Aspekte der Arbeit, wie wichtig es ist, Hardware und Algorithmen auf allen Ebenen gleichzeitig zu betrachten: Auf den Ebenen einzelner Instruktionen, eines Prozessors bzw. eines gesamten Systems

Flow simulation with locally-refined LBM

We simulate 3D fluid flow by a locally-refined lattice Boltzmann method (LBM) on graphics hardware. A low resolution LBM simulation running on a coarse grid models global flow behavior of the entire domain with low consumption of computational resources. For regions of interest where small visual details are desired, LBM simulations are performed on fine grids, which are separate grids superposed on the coarse one. The flow properties on boundaries of the fine grids are determined by the global simulation on the coarse grid. Thus, the locally refined fine-grid simulations follow the global fluid behavior, and model the desired small-scale and turbulent flow motion with their denser numerical discretization. A fine grid can be initiated and terminated at any time while the global simulation is running. It can also move inside the domain with a moving object to capture small-scale vortices caused by the object. Besides the performance improvement due to the adaptive simulation, the locally-refined LBM is suitable for acceleration on contemporary graphics hardware (GPU), since it involves only local and linear computations. Therefore, our approach achieves fast and adaptive 3D flow simulation for computer games and other interactive applications

Accelerating Radio Wave Propagation Algorithms by Implementation on Graphics Hardware

Radio wave propagation prediction is a fundamental prerequisite for planning, analysis and optimization of radio networks. For instance coverage analysis, interference estimation or channel and power allocation all rely on propagation predictions. In wireless communication networks optimal antenna sites are determined by either conducting a serie

Laser-plasma interactions as tools for studying processes in quantum electrodynamics

Conventional particle accelerators and astronomical observations have long been some of the only tools for studying processes in high energy physics. The development of laser-plasma sources and high gradient accelerators will therefore be a key asset to these studies. In particular, laser-plasma accelerators have favourable spatial and temporal properties for studies into intense processes, and can be readily coupled to a wide array of other laser-plasma sources creating unique environments. Here, coupling to an X-ray source and intense laser focus were used to study processes in quantum electrodynamics. To study the linear Breit-Wheeler process, a 40 ps laser was used to drive a volumetric X-ray emitter. Line emission from a thin-foil Ge target, produced a highly efficient (3.4%), dense source of 1.3 − 1.9 keV X-rays, with 3 ± 1 (stat.) ±0.4 (sys.) ×10^{12} photons/eV/sphere. These X-rays were collided with bremsstrahlung gamma rays (with energies up to 800 MeV) to investigate electron-positron pair production. The X-ray source was well-optimised for studying this interaction, and would allow the detection of Breit-Wheeler pairs if used with a moderately improved electron beam for generating bremsstrahlung (3× the highest electron energy and 5× the total charge, as achieved previously). This would constitute the first laser-plasma photon- photon collider with low virtuality (energy off mass-shell ≈ 10^{−20} MeV^2). In order to differentiate between competing models of electron radiation reaction in strong field quantum electrodynamics, a narrow energy-spread electron beam was studied. By utilising shock injection into a laser wakefield accelerator, a high energy (1260±40 MeV), narrow energy- spread (4.1±0.9 %) beam was generated. This is one of only a few studies that have successfully achieved these electron beam properties. While the shot-to-shot reproducibility of the electron beam was limited to 60%, the relative energy-spread was sufficiently small that differentiation of radiation reaction models could be readily achieved in future experiments. With the upcoming commissioning of many multi-PW laser facilities, these studies demonstrate how active research into quantum electrodynamics can be achieved on the smaller, more accessible, laser-laboratory scale.Open Acces

Ray Tracing Gems

This book is a must-have for anyone serious about rendering in real time. With the announcement of new ray tracing APIs and hardware to support them, developers can easily create real-time applications with ray tracing as a core component. As ray tracing on the GPU becomes faster, it will play a more central role in real-time rendering. Ray Tracing Gems provides key building blocks for developers of games, architectural applications, visualizations, and more. Experts in rendering share their knowledge by explaining everything from nitty-gritty techniques that will improve any ray tracer to mastery of the new capabilities of current and future hardware. What you'll learn: The latest ray tracing techniques for developing real-time applications in multiple domains Guidance, advice, and best practices for rendering applications with Microsoft DirectX Raytracing (DXR) How to implement high-performance graphics for interactive visualizations, games, simulations, and more Who this book is for: Developers who are looking to leverage the latest APIs and GPU technology for real-time rendering and ray tracing Students looking to learn about best practices in these areas Enthusiasts who want to understand and experiment with their new GPU

Efficient From-Point Visibility for Global Illumination in Virtual Scenes with Participating Media

Sichtbarkeitsbestimmung ist einer der fundamentalen Bausteine fotorealistischer Bildsynthese. Da die Berechnung der Sichtbarkeit allerdings äußerst kostspielig zu berechnen ist, wird nahezu die gesamte Berechnungszeit darauf verwendet. In dieser Arbeit stellen wir neue Methoden zur Speicherung, Berechnung und Approximation von Sichtbarkeit in Szenen mit streuenden Medien vor, die die Berechnung erheblich beschleunigen, dabei trotzdem qualitativ hochwertige und artefaktfreie Ergebnisse liefern