Scalable ray tracing with multiple GPGPUs

Rapid development in the field of computer graphics over the last 40 years has brought forth different techniques to render scenes. Rasterization is today’s most widely used technique, which in its most basic form sequentially draws thousands of polygons and applies texture on them. Ray tracing is an alternative method that mimics light transport by using rays to sample a scene in memory and render the color found at each ray’s scene intersection point. Although mainstream hardware directly supports rasterization, ray tracing would be the preferred technique due to its ability to produce highly crisp and realistic graphics, if hardware were not a limitation. Making an immediate hardware transition from rasterization to ray tracing would have a severe impact on the computer graphics industry since it would require redevelopment of existing 3D graphics-employing software, so any transition to ray tracing would be gradual. Previous efforts to perform ray tracing on mainstream rasterizing hardware platforms with a single processor have performed poorly. This thesis explores how a multiple GPGPU system can be used to render scenes via ray tracing. A ray tracing engine and API groundwork was developed using NVIDIA’s CUDA (Compute Unified Device Architecture) GPGPU programming environment and was used to evaluate performance scalability across a multi-GPGPU system. This engine supports triangle, sphere, disc, rectangle, and torus rendering. It also allows independent activation of graphics features including procedural texturing, Phong illumination, reflections, translucency, and shadows. Correctness of rendered images validates the ray traced results, and timing of rendered scenes benchmarks performance. The main test scene contains all object types, has a total of 32 Abstract objects, and applies all graphics features. Ray tracing this scene using two GPGPUs outperformed the single-GPGPU and single-CPU systems, yielding respective speedups of up to 1.8 and 31.25. The results demonstrate how much potential exists in treating a modern dual-GPU architecture as a dual-GPGPU system in order to facilitate a transition from rasterization to ray tracing

Teste de desempenho de padrões de Vulkan com path-tracing

Performance and low overhead are the selling points of modern graphics APIs, such as Vulkan API, when compared to previous versions. However, these come with added complexity over previous APIs. Understanding all involved API elements takes time and, sometimes, there is no clear perception of the bene ts and drawbacks in each. The thesis focus is to draw a clear view of a subset of Vulkan patterns and layout their pros and cons. The thesis features a path-tracer implemented in Vulkan uniquely out of Compute shaders. It is used to evaluate multi-threading, command scheduling and memory management e ects with a consistent test method. Furthermore, it also features a set of guidelines and abstractions created from Vulkan's work experience. These can be used to atten other API users learning curve or provide some improvement lines on existing applications.Desempenho e baixo consumo são as vantagens dadas pelas API gráficas modernas, como a API Vulkan, quando comparadas com as versões anteriores. Em contrapartida, também oferecem um maior grau de complexidade. É preciso tempo para perceber todos os elementos envolvidos, como também nem sempre é percetível quais os benefícios e perdas do uso desses mesmos elementos. O foco da dissertação é criar uma perspetiva nítida das vantagens e desvantagens em torno de determinados padrões em Vulkan. Esta dissertação avalia os efeitos de multi-threading, ordem de comandos e manipulação de memória, com base num método consistente, via um pathtracer feito unicamente de Compute shaders com Vulkan. Ainda junta toda a experiência de uso e conclusões num conjunto de guias e abstrações, a fim de ajudar a reduzir a curva de aprendizagem ou dar ideias sobre possíveis melhorias em aplicações existentes.Mestrado em Engenharia de Computadores e Telemátic

GPU Raytracer

Ray tracing je oblíbená metoda pro vytváření realistické grafiky, s velkou výpočetní složitostí a velkým potenciálem pro paralelizaci. Moderní GPU mohou sloužit jako výkonné paralelní koprocesory, díky čemuž se zdají být ideální nástroj pro ray tracing. Tato práce obsahuje přehled o technikách ray tracingu, přehled o technikách programování GPU, a představuje software vytvořený pro použití GPU pro ray tracing. Tento software se snaží spojit klasické metody pro ray tracing se specifickými vlastnostmi programování GPU, při zachování rozšiřitelnosti a vysoké rychlosti.Ray tracing is a popular method for generating realistic imagery, with high computation complexity and high potential for parallelization. Modern GPUs can be used as a high performance parallel co-processor, making them seemingly ideal for tasks such as ray tracing. This thesis will give an overview of ray tracing methods, overview of GPU computing methods, and present a piece of software designed for using GPU for ray tracing. This software tries to integrate classic ray tracing algorithms with specifics of GPU programming, while providing extendability and high performance.Department of Software and Computer Science EducationKatedra softwaru a výuky informatikyFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult

Mobile graphics: SIGGRAPH Asia 2017 course

Peer ReviewedPostprint (published version

GPU Optimization of an Existing Free-Viewpoint Video System

Many video reconstruction systems seek to recreate a scene from captured video sequences but are unable to perform at interactive framerates. This project presents the optimization of such a system by utilizing a Graphics Processing Unit (GPU). The specialized nature of the GPU offers many challenges in non-traditional graphics pipelines, but can offer great performance benefits. This paper presents the process by which a next-generation GPU is utilized to accelerate the visual hull reconstruction and rendering in Cinematized Reality

Ambient occlusion and shadows for molecular graphics

Computer based visualisations of molecules have been produced as early as the 1950s to aid researchers in their understanding of biomolecular structures. An important consideration for Molecular Graphics software is the ability to visualise the 3D structure of the molecule in a clear manner. Recent advancements in computer graphics have led to improved rendering capabilities of the visualisation tools. The capabilities of current shading languages allow the inclusion of advanced graphic effects such as ambient occlusion and shadows that greatly improve the comprehension of the 3D shapes of the molecules. This thesis focuses on finding improved solutions to the real time rendering of Molecular Graphics on modern day computers. The methods of calculating ambient occlusion and both hard and soft shadows are examined and implemented to give the user a more complete experience when navigating large molecular structures

Perceptually optimized real-time computer graphics

Perceptual optimization, the application of human visual perception models to remove imperceptible components in a graphics system, has been proven effective in achieving significant computational speedup. Previous implementations of this technique have focused on spatial level of detail reduction, which typically results in noticeable degradation of image quality. This thesis introduces refresh rate modulation (RRM), a novel perceptual optimization technique that produces better performance enhancement while more effectively preserving image quality and resolving static scene elements in full detail. In order to demonstrate the effectiveness of this technique, a graphics framework has been developed that interfaces with eye tracking hardware to take advantage of user fixation data in real-time. Central to the framework is a high-performance GPGPU ray-tracing engine written in OpenCL. RRM reduces the frequency with which pixels outside of the foveal region are updated by the ray-tracer. A persistent pixel buffer is maintained such that peripheral data from previous frames provides context for the foveal image in the current frame. Traditional optimization techniques have also been incorporated into the ray-tracer for improved performance. Applying the RRM technique to the ray-tracing engine results in a speedup of 2.27 (252 fps vs. 111 fps at 1080p) for the classic Whitted scene with reflection and transmission enabled. A speedup of 3.41 (140 fps vs. 41 fps at 1080p) is observed for a high-polygon scene that depicts the Stanford Bunny. A small pilot study indicates that RRM achieves these results with minimal impact to perceived image quality. A secondary investigation is conducted regarding the performance benefits of increasing physics engine error tolerance for bounding volume hierarchy based collision detection when the scene elements involved are in the user\u27s periphery. The open-source Bullet Physics Library was used to add accurate collision detection to the full resolution ray-tracing engine. For a scene with a static high-polygon model and 50 moving spheres, a speedup of 1.8 was observed for physics calculations. The development and integration of this subsystem demonstrates the extensibility of the graphics framework

Tessellated Voxelization for Global Illumination using Voxel Cone Tracing

Modeling believable lighting is a crucial component of computer graphics applications, including games and modeling programs. Physically accurate lighting is complex and is not currently feasible to compute in real-time situations. Therefore, much research is focused on investigating efficient ways to approximate light behavior within these real-time constraints. In this thesis, we implement a general purpose algorithm for real-time applications to approximate indirect lighting. Based on voxel cone tracing, we use a filtered representation of a scene to efficiently sample ambient light at each point in the scene. We present an approach to scene voxelization using hardware tessellation and compare it with an approach utilizing hardware rasterization. We also investigate possible methods of warped voxelization. Our contributions include a complete and open-source implementation of voxel cone tracing along with both voxelization algorithms. We find similar performance and quality with both voxelization algorithms

An interest point based illumination condition matching approach to photometric registration within augmented reality worlds

With recent and continued increases in computing power, and advances in the field of computer graphics, realistic augmented reality environments can now offer inexpensive and powerful solutions in a whole range of training, simulation and leisure applications. One key challenge to maintaining convincing augmentation, and therefore user immersion, is ensuring consistent illumination conditions between virtual and real environments, so that objects appear to be lit by the same light sources. This research demonstrates how real world lighting conditions can be determined from the two-dimensional view of the user. Virtual objects can then be illuminated and virtual shadows cast using these conditions. This new technique uses pairs of interest points from real objects and the shadows that they cast, viewed from a binocular perspective, to determine the position of the illuminant. This research has been initially focused on single point light sources in order to show the potential of the technique and has investigated the relationships between the many parameters of the vision system. Optimal conditions have been discovered by mapping the results of experimentally varying parameters such as FoV, camera angle and pose, image resolution, aspect ratio and illuminant distance. The technique is able to provide increased robustness where greater resolution imagery is used. Under optimal conditions it is possible to derive the position of a real world light source with low average error. An investigation of available literature has revealed that other techniques can be inflexible, slow, or disrupt scene realism. This technique is able to locate and track a moving illuminant within an unconstrained, dynamic world without the use of artificial calibration objects that would disrupt scene realism. The technique operates in real-time as the new algorithms are of low computational complexity. This allows high framerates to be maintained within augmented reality applications. Illuminant updates occur several times a second on an average to high end desktop computer. Future work will investigate the automatic identification and selection of pairs of interest points and the exploration of global illuminant conditions. The latter will include an analysis of more complex scenes and the consideration of multiple and varied light sources.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Photorealistic Rendering Using "Photon Mapping" Method

Tato práce se zabýva metodou photon mappingu. Nejprve byla naimplementována jednoduchá metoda photon mappingu a poté jeji progresivní varianta byla naimplementována na procesoru a grafické kartě. Po implementaci progressivní varianty photon mappingu na GPU, několik akceleračních technik bylo navrženo. Na konci této práce byl představený genetický klustrovací algoritmus, který se snaží pomocí vhodnějších clusterů urychlit čas výpočtu photon mappingu na gpu.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.