In the past, ray tracing has been used widely in offline rendering applications since it provided the ability to better capture high quality secondary effects such as reflection, refraction and shadows. Such effects are difficult to produce in a robust, high quality fashion with traditional, real-time rasterization algorithms. Motivated to bring the advantages to ray tracing to real-time applications, researchers have developed better and more efficient algorithms that leverage the current generation of fast, parallel CPU hardware within the past few years. This thesis provides the implementation and design details of a high performance ray tracing solution called ``RTTest'' for standard, desktop CPUs. Background information on various algorithms and acceleration structures are first discussed followed by an introduction to novel techniques used to better accelerate current, core ray tracing techniques. Techniques such as Omni-Directional Packets, Cone Proxy Traversal and Multiple Frustum Traversal are proposed and benchmarked using standard ray tracing scenes. Also, a novel soft shadowing algorithm called Edge Width Soft Shadows is proposed which achieves performance comparable to a single sampled hard shadow approach targeted at real time applications such as games. Finally, additional information on the memory layout, rendering pipeline, shader system and code level optimizations of RTTest are also discussed.

In the past, ray tracing has been used widely in offline rendering applications since it provided the ability to better capture high quality secondary effects such as reflection, refraction and shadows. Such effects are difficult to produce in a robust, high quality fashion with traditional, real-time rasterization algorithms. Motivated to bring the advantages to ray tracing to real-time applications, researchers have developed better and more efficient algorithms that leverage the current generation of fast, parallel CPU hardware within the past few years. This thesis provides the implementation and design details of a high performance ray tracing solution called ``RTTest'' for standard, desktop CPUs. Background information on various algorithms and acceleration structures are first discussed followed by an introduction to novel techniques used to better accelerate current, core ray tracing techniques. Techniques such as Omni-Directional Packets, Cone Proxy Traversal and Multiple Frustum Traversal are proposed and benchmarked using standard ray tracing scenes. Also, a novel soft shadowing algorithm called Edge Width Soft Shadows is proposed which achieves performance comparable to a single sampled hard shadow approach targeted at real time applications such as games. Finally, additional information on the memory layout, rendering pipeline, shader system and code level optimizations of RTTest are also discussed.

Shadows provide an important cue in computer graphics. In this thesis we focus on real-time soft shadow algorithms. Two new techniques are presented, both run entirely on modern graphics hardware. "Soft Shadows Using Precomputed Visibility Distance Functions" renders fake soft shadows in static scenes using precomputed visibility information. The technique handles dynamic local light sources and contains special computation steps to generate smooth shadows from hard visibility functions. The resulting images are not physically accurate, nevertheless the method renders plausible images that imitate global illumination. "Soft Projected Shadows" is a simple method for simulating natural shadow penumbra for projected grayscale shadow textures. Shadow blurring is performed entirely in image space and needs only a couple of special blurring passes on pixel shader 2.0 hardware. The technique treats shadow receivers as nearly planar surfaces and doesn’t handle self shadowing, but executes very fast and renders plausible soft shadows. Multiple overlapping shadow casters in a single shadow map are natively supported without any performance overhead.

Background. Ray tracing is a tool that can be used to increase the quality of the graphics in games. One application in graphics that ray tracing excels in is generating shadows because ray tracing can simulate how shadows are generated in real life more accurately than rasterization techniques can. With the release of GPUs with hardware support for ray tracing, it can now be used in real-time graphics applications to some extent. However, it is still a computationally heavy task requiring performance improvements. Objectives. This thesis will evaluate the difference in performance of three raytracing methods in DXR Tier 1.1, namely dynamic ray tracing and two forms of inline ray tracing. To further investigate the ray-tracing performance, soft shadows will be implemented to see if the driver can perform optimizations differently (depending on the choice of ray-tracing method) on the subsequent and/or preceding API interactions. With the pipelines implemented, benchmarks will be performed using different GPUs, scenes, and a varying amount of shadow-casting lights. Methods. The scientific method is based on an experimental approach, using both implementation and performance tests. The experimental approach will begin by extending an in-house DirectX 12 renderer. The extension includes ray-tracing functionality, so that hard shadows can be generated using both dynamic- and the inline forms ray tracing. Afterwards, soft shadows are generated by implementing a state-of-the-art-denoiser with some modifications, which will be added to each ray-tracing method. Finally, the renderer is used to perform benchmarks of various scenes with varying amounts of shadow-casting lights and object complexity to cover a broad area of scenarios that could occur in a game and/or in other similar applications. Results and Conclusions. The results gathered in this experiment suggest that under the experimental conditions of the chosen scenes, objects, and number of lights, AMD’s GPUs were faster in performance when using dynamic ray tracing than using inline ray tracing, whilst Nvidia’s GPUs were faster when using inline ray tracing compared to when using dynamic ray tracing. Also, with an increasing amount of shadow-casting lights, the choice of ray-tracing method had low to no impact except for linearly increasing the execution time in each test. Finally, adding soft shadows(subsequent and preceding API interactions) also had low to no relative impact on the results depending on the different ray-tracing methods. / Bakgrund. Strålspårning (ray tracing) är ett verktyg som kan användas för att öka kvalitén på grafiken i spel. En tillämpning i grafik som strålspårning utmärker sig i är när skuggor ska skapas eftersom att strålspårning lättare kan simulera hur skuggor skapas i verkligheten, vilket tidigare tekniker i rasterisering inte hade möjlighet för. Med ny hårdvara där det finns support för strålspårning inbyggt i grafikkorten finns det nu möjligheter att använda strålspårning i realtids-applikationer inom vissa gränser. Det är fortfarande tunga beräkningar som behöver slutföras och det är därav att det finns behov av förbättringar.  Syfte. Denna uppsats kommer att utvärdera skillnaderna i prestanda mellan tre olika strålspårningsmetoder i DXR nivå 1.1, nämligen dynamisk strålspårning och två olika former av inline strålspårning. För att ge en bredare utredning på prestandan mellan strålspårningsmetoderna kommer mjuka skuggor att implementeras för att se om drivrutinen kan göra olika optimiseringar (beroende på valet av strålspårningsmetod) på de efterföljande och/eller föregående API anropen. Efter att dessa rörledningar (pipelines) är implementerade kommer prestandatester att utföras med olika grafikkort, scener, och antal ljus som kastar skuggor. Metod. Den vetenskapliga metoden är baserat på ett experimentellt tillvägagångssätt, som kommer innehålla både ett experiment och ett flertal prestandatester. Det experimentella tillvägagångssättet kommer att börja med att utöka en egenskapad DirectX 12 renderare. Utökningen kommer tillföra ny funktionalitet för att kunna hantera strålspårning så att hårda skuggor ska kunna genereras med både dynamisk och de olika formerna av inline strålspårning. Efter det kommer mjuka skuggor att skapas genom att implementera en väletablerad avbrusningsteknik med några modifikationer, vilket kommer att bli tillagt på varje strålspårningssteg. Till slut kommer olika prestandatester att mätas med olika grafikkort, olika antal ljus, och olika scener för att täcka olika scenarion som skulle kunna uppstå i ett spel och/eller i andra liknande applikationer.  Resultat och Slutsatser. De resultat från testerna i detta experiment påvisar att under dessa förutsättningar så är AMD’s grafikkort snabbare på dynamisk strålspårning än på inline strålspårning, samtidigt som Nvidias grafikkort är snabbare på inline strålspårning än på den dynamiska varianten. Ökandet av ljus som kastar skuggor påvisade låg till ingen förändring förutom ett linjärt ökande av exekveringstiden i de flesta testerna. Slutligen så visade det sig även att tillägget av mjuka skuggor (efterföljande och föregående API interaktioner) hade låg till ingen påverkan på valet av strålspårningsmetod.

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This thesis discusses two different methods for creating soft shadows. Shadow volumes and shadow mapping, more accurately Variance Soft Shadow Mapping. It presents theory for these shadow algorithms as well as theory for few others which are necessary for understanding. Further it describes how to implement these methods and evaluates these implementations. Shadow volumes are based on creating additional geometry to the scene which serves for specifying region of penumbra. VSSM algorithm is a improved version of classic shadow mapping.

This thesis is concerned in the method of realistic rendering using a distributed raytracing. This method simulates various visual effects and generates high realistic 2D images. The work analyses the problem and explains principles of solution related to this technique. There is also descriprion of the method of simple reytracing which provides a basis for the distributed raytracing. A part of work is specialized for optimalization of distributed raytracing.

This thesis focuses on 3D computer graphics and the continuous maximisation of rendering quality and performance. Its main focus is the critical analysis of numerous real-time rendering algorithms and the construction of an empirically derived system for the high-speed rendering of shader-based special effects, lighting effects, shadows, reflection and refraction, post-processing effects and the processing of physics. This critical analysis allows us to assess the relationship between rendering quality and performance. It also allows for the isolation of key algorithmic weaknesses and possible bottleneck areas. Using this performance data, gathered during the analysis of various rendering algorithms, we are able to define a selection engine to control the real-time cycling of rendering algorithms and special effects groupings based on environmental conditions. Furthermore, as a proof of concept, to balance Central Processing Unit (CPU) and Graphic Processing Unit (GPU) load for and increased speed of execution, our selection system unifies the GPU and CPU as a single computational unit for physics processing and environmental mapping. This parallel computing system enables the CPU to process cube mapping computations while the GPU can be tasked with calculations traditionally handled solely by the CPU. All analysed and benchmarked algorithms were implemented as part of a modular rendering engine. This engine offers conventional first-person perspective input control, mesh loading and support for shader model 4.0 shaders (via Microsoft’s High Level Shader Language) for effects such as high dynamic range rendering (HDR), dynamic ambient lighting, volumetric fog, specular reflections, reflective and refractive water, realistic physics, particle effects, etc. The test engine also supports the dynamic placement, movement and elimination of light sources, meshes and spatial geometry. Critical analysis was performed via scripted camera movement and object and light source additions – done not only to ensure consistent testing, but also to ease future validation and replication of results. This provided us with a scalable interactive testing environment as well as a complete solution for the rendering of computationally intensive 3D environments. As a full-fledged game engine, our rendering engine is amenable to first- and third-person shooter games, role playing games and 3D immersive environments. Evaluation criteria (identified to access the relationship between rendering quality and performance), as mentioned, allows us to effectively cycle algorithms based on empirical results and to distribute specific processing (cube mapping and physics processing) between the CPU and GPU, a unification that ensures the following: nearby effects are always of high-quality (where computational resources are available), distant effects are, under certain conditions, rendered at a lower quality and the frames per second rendering performance is always maximised. The implication of our work is clear: unifying the CPU and GPU and dynamically cycling through the most appropriate algorithms based on ever-changing environmental conditions allow for maximised rendering quality and performance and shows that it is possible to render high-quality visual effects with realism, without overburdening scarce computational resources. Immersive rendering approaches used in conjunction with AI subsystems, game networking and logic, physics processing and other special effects (such as post-processing shader effects) are immensely processor intensive and can only be successfully implemented on high-end hardware. Only by cycling and distributing algorithms based on environmental conditions and through the exploitation of algorithmic strengths can high-quality real-time special effects and highly accurate calculations become as common as texture mapping. Furthermore, in a gaming context, players often spend an inordinate amount of time fine-tuning their graphics settings to achieve the perfect balance between rendering quality and frames-per-second performance. Using this system, however, ensures that performance vs. quality is always optimised, not only for the game as a whole but also for the current scene being rendered – some scenes might, for example, require more computational power than others, resulting in noticeable slowdowns, slowdowns not experienced thanks to our system’s dynamic cycling of rendering algorithms and its proof of concept unification of the CPU and GPU. / Thesis (PhD)--University of Pretoria, 2012. / Computer Science / unrestricted

This thesis deals with the method of distributed ray tracing focusing on optimalization of this method. The method uses simulation of some attributes of light by distributing rays of lights and it produces high quality and partly realistic images. The price for realitic effects is the high computational complexity of the method. The thesis analysis the theory connected with these aspects. A large part describes optimalizations of this method, i.e. searching for the nearest triangle intersection using kd-trees, quasi random sampling with faster convergence, the use of SSE instruction set and fast ray - triangle intersection. These optimalizations brought a noticable speed - up. The thesis includes description of implementation of these techniques. The implementation itself emphasises the practical usability including generating some advanced animations and universal description of objects.

The aim of this work was to create a program to visualize voxel scenes in real time using ray tracing. It included the study of various methods of such a rendering with a focus on shadows. The solution was created using Unity engine and experimental packages Unity Jobs and Burst. The thesis presents multiple ray tracing passes and SVGF technique, that is used to turn a noisy input into full edge-preserving image. The final program is able to render hard shadows, soft shadows, and ambient occlusion at speed of fifty frames per second.