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.

Recently, methods were developed to render various global illumination e&#64256;ects with rasterization GPUs. Among those were hardware based ray tracing and photon mapping. However, due to current GPU??s inherent architectural limitations, the e&#64259;ciency and throughput of these methods remained low. In this thesis, we propose a coherent rendering system that addresses these issues. First, we introduce new photon mapping and ray racing acceleration algorithms that facilitate data coherence and spatial locality, as well as eliminating unnecessary random memory accesses. A high level abstraction of the combined ray tracing and photon mapping streaming pipeline is introduced. Based on this abstraction, an e&#64259;cient ray tracing and photon mapping GPU is designed. Using an event driven simulator, developed for this GPU, we verify and validate the proposed algorithms and architecture. Simulation results have validated better interactive performances compared to the current GPUs.

Within the last decade, the offline rendering branch of computer graphics has moved towards the concept of physically-based rendering by using the path tracing algorithm. One such physically-based effect is fluorescence, where light is absorbed at one wavelength and re-emitted at another. However, to properly capture this effect, one has to utilize spectral path tracing, as opposed to colour- based path tracing. Spectral path tracing by itself suffers from colour noise, which can be reduced by utilizing the so-called Hero Wavelength Spectral Sampling (HWSS). The inclusion of wavelength shifting induced by fluorescence requires modifications to the base path tracing algorithm that HWSS wasn't designed for. This thesis provides the overview of path tracing, the current state-of-art for in- clusion of fluorescence in a rendering system, along with relevant technical details, the overview of HWSS itself as well as mathematical formulation that enables the combination of fluorescence and HWSS. Additionally, this thesis also proposes a new approach to rendering fluorescent participating media that properly handles previously overlooked failure cases. 1

Context. Indirect illumination – the light contribution from bounce light in an environment – is an important effect when creating realistic images. Historically it has been approximated very poorly by applying a constant ambient term. This approximation is unacceptable if the goal is to create realistic results as bouncing light contributes a lot of light in the real world. Objectives. This thesis proposes a technique to use a reflective shadow map to place and configure spotlights in an environment to approximate global illumination. Methods. The proposed spotlight distribution technique is implemented in a delimited real time graphics engine, and the results are compared to a naive spotlight distribution method. Results. The image resulting from the proposed technique has a lower quality than the comparison in our test scene. Conclusions. The technique could be used in its current state for applications where the view can be controlled by the developer such as in 3D side scrolling games or as a tool to generate editable indirect illumination. Further research needs to be conducted to make it more broadly viable. / Indirekt illuminering är en viktigt effekt om en försöker skapa realistiska bilder. Den här uppsatsen föreslår en teknik där en reflektiv skuggkarta används för att placera och konfigurera strålkastare för att approximera indirekt illuminering. Tekniken kan användas i till exempel sidscrollande 3D spel eller för att skapa ett verktyg som kan användas för att skapa redigerbar indirekt illuminering. Vidare forskning krävs för att göra tekniken rimlig för flera användningsområden.

This master thesis focuses on photon mapping rendering technique. A simple photon mapping was implemented as a baseline and then progressive photon mapping was prepared for CPU and GPU. After implementing progressive photon mapping on GPU, further acceleration techniques were proposed. Finally, in the thesis, genetic clustering algorithm for suitable clusters on GPU was proposed.

This dissertation explores algorithms for rendering optimization realizable within a modern, complex rendering engine. The first part contains optimized rendering algorithms for ray tracing. Ray tracing algorithms typically provide properties of simplicity and robustness that are highly desirable in computer graphics. We offer several novel contributions to the problem of interactive ray tracing of complex lighting environments. We focus on the problem of maintaining interactivity as both geometric and lighting complexity grows without effecting the simplicity or robustness of ray tracing. First, we present a new algorithm called occlusion caching for accelerating the calculation of direct lighting from many light sources. We cache light visibility information sparsely across a scene. When rendering direct lighting for all pixels in a frame, we combine cached lighting information to determine whether or not shadow rays are needed. Since light visibility and scene location are highly correlated, our approach precludes the need for most shadow rays. Second, we present improvements to the irradiance caching algorithm. Here we demonstrate a new elliptical cache point spacing heuristic that reduces the number of cache points required by taking into account the direction of irradiance gradients. We also accelerate irradiance caching by efficiently and intuitively coupling it with occlusion caching. In the second part of this dissertation, we present optimizations to rendering algorithms for participating media. Specifically, we explore the implementation and use of photon beams as an efficient, intuitive artistic primitive. We detail our implementation of the photon iii beams algorithm into PhotoRealistic RenderMan (PRMan). We show how our implementation maintains the benefits of the industry standard Reyes rendering pipeline, with proper motion blur and depth of field. We detail an automatic photon beam generation algorithm, utilizing PRMan shadow maps. We accelerate the rendering of camera-facing photon beams by utilizing Gaussian quadrature for path integrals in place of ray marching. Our optimized implementation allows for incredible versatility and intuitiveness in artistic control of volumetric lighting effects. Finally, we demonstrate the usefulness of photon beams as artistic primitives by detailing their use in a feature-length animated film.

The growing demand for realistic renderings in both film and games has led to a number of proposed solutions to the Global Illumination problem. In order to imitate natural lighting, it is necessary to gather indirect illumination of the surrounding environment for lighting computations. This is a computationally expensive problem, requiring the sampling or rasterization of the hemisphere surrounding each ray intersection, to which there is no standardized solution. In this thesis we propose a new method of approximation using environment maps for caching radiance. The proposed method leverages a voxelized scene representation for storing direct illumination and a cache of environment maps for integrating indirect illumination. By using a voxelized scene to gather indirect lighting contributions and caching these contributions spatially, we are able to achieve fast and convincing renders of large complex scenes. The result of our implementation produces images comparable to those of existing Monte Carlo integration methods with render speeds a magnitude or more faster.

The object of this work is to create software implementing two algorithms for global ilumination computing. Iradiance and radiance caching should be implemented in CUDA framework on graphics card (GPU). Parallel implementation on GPU should dramatically improve algoritm speed compared to CPU implementation. The software will be written using already done framework for global illumunation computation. That allow to focus to algorithm implementation only. This work should speed up testing of new or existing methods for global illumination computing, because saving and reusing of intermediate results can be used for other algorithms too. Powered by TCPDF (www.tcpdf.org)

This diploma thesis deals with global illumination and generally with the process of illumination of prepared scenes. A program for illumination management was written for this purpose. It can manage both direct and indirect illumination in interactive time. Simple and comfortable user interface allows for addition, deletion and change in light settings. Different types of both point and area lights are supported. In the course of all work, the program displays current illumination of the scene. With the help of this application, a series of different experiments will be carried out. We will explore the way users work during illumination, the way they perceive different properties of global illumination, various options of its control and its comparison with common direct illumination.

The objective of this work is to create software implementing two algorithms for global ilumination computation. Iradiance and radiance caching should be implemented in CUDA framework on a graphics card (GPU). Parallel implementation on the GPU should improve algoritm speed compared to CPU implementation. The software will be written using an already done framework for global illumunation computation. That allows to focus on algorithm implementation only. This work should speed up testing of new or existing methods for global illumination computing, because saving and reusing of intermediate results can be used for other algorithms too. Powered by TCPDF (www.tcpdf.org)