Le rendu photo-réaliste traditionnel exige un effort manuel et des calculs intensifs pour créer des scènes et rendre des images réalistes. C'est principalement pour cette raison que la création de contenus pour l’imagerie numérique de haute qualité a été limitée aux experts et le rendu hautement réaliste nécessite encore des temps de calcul significatifs. Le rendu basé image (IBR) est une alternative qui a le potentiel de rendre les applications de création et de rendu de contenus de haute qualité accessibles aux utilisateurs occasionnels, puisqu'ils peuvent générer des images photo-réalistes de haute qualité sans subir les limitations mentionnées ci-dessus. Nous avons identifié trois limitations importantes des méthodes actuelles de rendu basé image : premièrement, chaque algorithme possède des forces et faiblesses différentes, en fonction de la qualité de la reconstruction 3D et du contenu de la scène, et un seul algorithme ne permet souvent pas d’obtenir la meilleure qualité de rendu partout dans l’image. Deuxièmement, ces algorithmes présentent de forts artefacts lors du rendu d’objets manquants ou partiellement reconstruits. Troisièmement, la plupart des méthodes souffrent encore d'artefacts visuels significatifs dans les régions de l’image où la reconstruction est de faible qualité. Dans l'ensemble, cette thèse propose plusieurs améliorations significatives du rendu basé image aussi bien en termes de vitesse de rendu que de qualité d’image. Ces nouvelles solutions sont basées sur le rendu sélectif, la substitution de modèle basé sur l'apprentissage, et la prédiction et la correction des erreurs de profondeur. / Traditional photo-realistic rendering requires intensive manual and computational effort to create scenes and render realistic images. Thus, creation of content for high quality digital imagery has been limited to experts and highly realistic rendering still requires significant computational time. Image-Based Rendering (IBR) is an alternative which has the potential of making high-quality content creation and rendering applications accessible to casual users, since they can generate high quality photo-realistic imagery without the limitations mentioned above. We identified three important shortcomings of current IBR methods: First, each algorithm has different strengths and weaknesses, depending on 3D reconstruction quality and scene content and often no single algorithm offers the best image quality everywhere in the image. Second, such algorithms present strong artifacts when rendering partially reconstructed objects or missing objects. Third, most methods still result in significant visual artifacts in image regions where reconstruction is poor. Overall, this thesis addresses significant shortcomings of IBR for both speed and image quality, offering novel and effective solutions based on selective rendering, learning-based model substitution and depth error prediction and correction.

This master's thesis deals with the creation of visual effects in 3D graphics applications. Rendering scenes using rasterization method and OpenGL library is assumed. The theoretical part describes several selected effects and then analyzes the approach used for their implementation. It focuses on the principles of rendering passes. Subsequently, the thesis focuses on the development of a software library which aims to simplify the process of programming effects. The resulting library reduces the time and knowledge required for the creation of effects. Automatic shader code generation is performed. Substantial feature is also the possibility to combine definitions of effects into a single unit.

The aim of this work is to create a simple raytracer with IPP library, which will use the frameless rendering technique. The first part of this work focuses on the raytracing method. The next part analyzes the frameless rendering technique and its adaptive version with focus on adaptive sampling. Third part describes the IPP library and implementation of a simple raytracer using this library. The last part evaluates the speed and rendering quality of the implemented system.

The goal of master’s thesis was to demonstrate and benchmark peformance of Mantle and Vulkan APIs with different optimization methods. This thesis proposes a rendering toolkit with optimization methods based on parallel command buffer generating, persistent staging buffers mapping, minimal pipeline configuration and descriptor sets changing, device memory pre-allocating with managing and sharing between multiple resources. The result is reference implementation that could render dynamic scene with thousands of objects in real time.

La représentation des phénomènes météorologiques est un enjeu essentiel en Informatique Graphique dans l’optique d’obtenir des scènes extérieures visuellement réalistes. Depuis quelques années, les chercheurs se sont penchés sur la simulation de la pluie en synthèse d’images. Ce mémoire a pour but de présenter deux méthodes de rendu : une première méthode pour le rendu de la pluie, et une seconde pour le rendu des égouttements provenant des arbres. Notre modèle de rendu de pluie est une méthode multi-échelle permettant de tenir compte des propriétés locales et globales de ce phénomène. Nous avons réussi à mettre en corrélation la densité des gouttes proches de l’observateur (échelle mésoscopique) avec l’atténuation de la visibilité (échelle macroscopique), en fonction d’un seul paramètre global cohérent : l’intensité des précipitations. Cette méthode a fait l’objet d’une publication [56] dans la revue Computers & Graphics en 2015. D’autre part, nous basons notre méthode pour le rendu des égouttements sur une approche phénoménologique. Une telle approche s’avère plus adaptée pour gérer les grands espaces, et présente l’avantage d’être indépendante de la complexité de la scène. L’approche choisie s’appuie sur des expérimentations et des mesures hydrologiques effectuées par des chercheurs spécialisés dans l’hydrologie des forêts. Nous proposons ainsi un modèle d’égouttement cohérent, tenant compte des propriétés intrinsèques à chaque type d’arbres. Cette méthode a fait elle aussi l’objet d’une présentation à la conférence Eurographics Symposium on Rendering (EGSR) ainsi qu’une publication [57] au journal Computer Graphics Forum (CGF) en 2016. / This dissertation aims to present a coherent multiscale model for real-time rain rendering which takes into account local and global properties of rainy scenes. Our goal is to simulate visible rain streaks close to the camera as well as the progressive loss of visibility induced by atmospheric phenomena. Our model proposes to correlate the attenuation of visibility, which is due in part to the extinction phenomenon, and the distribution of raindrops in terms of rainfall intensity and camera's parameters. Furthermore, this method proposes an original rain streaks generation based on spectral analysis and sparse convolution theory. This allows an accurate control of rainfall intensity and streaks appearance, improving the global realism of rainy scenes. We also aim at rendering interactive visual effects inherent to complex interactions between trees and rain in real-time in order to increase the realism of natural rainy scenes. Such a complex phenomenon involves a great number of physical processes influenced by various interlinked factors and its rendering represents a thorough challenge in Computer Graphics. We approach this problem by introducing an original method to render drops dripping from leaves after interception of raindrops by foliage. Our method introduces a new hydrological model representing interactions between rain and foliage through a phenomenological approach. Our model reduces the complexity of the phenomenon by representing multiple dripping drops with a new fully functional form evaluated per-pixel on-the-fly and providing improved control over density and physical properties. Furthermore, an efficient real-time rendering scheme, taking full advantage of latest GPU hardware capabilities, allows the rendering of a large number of dripping drops even for complex scenes.

Point-based rendering methods have proven to be effective for the display of large point cloud surface models. For a realistic visualization of the models, transparency and shadows are essential features. We propose a method for point cloud rendering with transparency and shadows at interactive rates. Our approach does not require any global or local surface reconstruction method, but operates directly on the point cloud. All passes are executed in image space and no pre-computation steps are required. The underlying technique for our approach is a depth peeling method for point cloud surface representations. Having detected a sorted sequence of surface layers, they can be blended front to back with given opacity values to obtain renderings with transparency. These computation steps achieve interactive frame rates. For renderings with shadows, we determine a point cloud shadow texture that stores for each point of a point cloud whether it is lit by a given light source. The extraction of the layer of lit points is obtained using the depth peeling technique, again. For the shadow texture computation, we also apply a Monte-Carlo integration method to approximate light from an area light source, leading to soft shadows. Shadow computations for point light sources are executed at interactive frame rates. Shadow computations for area light sources are performed at interactive or near-interactive frame rates depending on the approximation quality.

Although proprietary and free web map applications have become an important part of daily life, individual map styling has been neglected for a fairly long time. With the latest possibilities of custom adjustment provided by many services and some interesting artistic experiments, this is about to change. In the context of artistic cartography and custom map styling, this work explores the possibilities of employing an automated process for the generation of WMTS compatible map tiles with an artistic styling. Web mapping standards and techniques of non-photorealistic rendering (NPR) are considered as well as traditional cartographic representations. Furthermore, existing vector- and raster-based processes are analyzed including an interactive workflow with the open-source image editing software GIMP, which is examined with respect to its drawing capabilities. Based on this, a concept for an automated rendering process is developed and influencing factors along with input parameters are discussed. An experimental automated processing is implemented using GIMP and its Python scripting interface to create single maps and seamless map tiles for the use in a WMTS application. Different drawing techniques of GIMP, such as brushes, dynamics and masks are applied during the rendering process. Geodata is taken from the freely available OpenStreetMap project and it is stored in a geodatabase. Furthermore, the GIS capabilities of the database are used to implement custom query procedures for the creation of seamless tiles, feature simplification and generalization that makes a preprocessing of the data unnecessary. Additionally randomization methods for the estrangement and abstraction of the SVG vector graphics geometry to emulate a hand-drawn appearance are created based on non-photorealistic rendering techniques. As a result, various rendering and abstraction processes are evaluated and discussed regarding their contribution to an artistic appearance. Map tiles are created using these stylings which are WMTS compatible and can be presented in a web mapping application.:Contents Task Description III Abstract V Declaration of authorship VII Acknowledgements IX Table of Contents XIII List of Figures XVI List of Tables XVIII Glossary XX 1 Introduction1 1.1 Motivation 1 1.2 Objectives 1 1.3 Structure of the work 2 2 Cartographic context and NPR 5 2.1 Definitions 5 2.2 Non-photorealistic rendering 7 2.2.1 NPR in computer graphics 7 2.2.2 Hand-drawn rendering 10 2.3 Cartographic communication and visualization 12 2.4 Cartography and art 14 2.5 Web Mapping 17 3 Image editing and web map rendering 19 3.1 Image editing software 19 3.2 Raster image editing with GIMP 20 3.2.1 Interactive editing 20 3.2.2 Plug-ins and scripting 28 3.3 Map rendering 31 3.3.1 Web map rendering techniques 31 3.3.2 Comparison of vector and raster based approaches 33 3.3.3 An interactive workflow with GIMP 36 4 A concept for automated processing 39 4.1 Comparison of influencing factors of a vector and raster based approach 39 4.2 Requirements and goals of automation 41 4.3 Definition of input parameters 43 4.4 Concept for an automated process with GIMP 43 4.5 Technical components 45 4.5.1 JSON 45 4.5.2 OpenStreetMap 46 4.5.3 Database environment 47 4.5.4 SVG as exchange format 47 4.5.5 Web map tile service 49 5 Implementation of an automated process with GIMP 53 5.1 Geodata setup 53 5.1.1 Data acquisition 53 5.1.2 Data import and update 54 5.2 Sketch rendering 56 5.2.1 Displacement and randomization 57 5.2.2 Hand-drawn emulation 60 5.2.3 Hatching 64 5.3 Automated processing 65 5.3.1 Configuration files 66 5.3.2 Script structure 70 5.3.3 Feature Processing 74 5.3.4 Image rendering 78 5.3.5 Output and WMTS 80 6 Processing results and evaluation 83 6.1 Results 83 6.2 Limitations and potential 87 7 Conclusion 93 7.1 Summary 93 7.2 Outlook 94

Die Verwendung von ikonographischen, bildhaften Kartenzeichen ist sehr beliebt bei der Darstellung von Sehenswürdigkeiten in touristischen Karten sowie bei Kartendarstellungen für Kinder und Jugendliche. Der Begriff des Non-Photorealistic Rendering (NPR) beschreibt einen zentralen Bereich in der Computergrafik, der sich mit der Erzeugung von Bildern auseinandersetzt, die scheinbar handgemacht sind und bewusst nicht dem physikalisch korrekten Abbild eines Modells entsprechen. Ein weiteres Trendthema zur Nachahmung eines bestimmten Stils eines Kunstwerks stellt der Neural Style Transfer (NST) dar. Hierbei werden künstlerische Bilder durch Trennung und Rekombination von Bildinhalt und Stil erzeugt. Im Rahmen der vorliegenden Arbeit ist ein semi-automatischer Workflow zur Erzeugung ikonographischer Gebäudedarstellungen für die Nutzung in zoombaren Webkarten entwickelt und in drei künstlerischen Stilvarianten unter Nutzung von Bildverarbeitungswerkzeugen in dem rasterbasierten Open Source Bildbearbeitungsprogramm GIMP, speziell mit der Filtersammlung G'MIC technisch umgesetzt worden. Außerdem zeigt die Masterarbeit das Potential der Ableitung von ikonographischen Signaturen durch den Style-Transfer mittels neuronaler Netze.:Selbstständigkeitserklärung III Inhaltsverzeichnis 5 Abbildungsverzeichnis 7 Tabellenverzeichnis 8 Abkürzungsverzeichnis 9 1 Einleitung 10 1.1 Motivation 10 1.2 Gliederung der Arbeit 10 2 Literaturstudium 11 2.1 Computergrafik 11 2.2 Non-Photorealistic Rendering 11 2.3 Neural Style Transfer 14 2.3.1 Einleitung 14 2.3.2 Convolutional Neural Network 15 2.3.3 Beschreibung des Algorithmus 17 3 Methodik 19 3.1 Technische Komponenten 19 3.2 Kriterien der Bildauswahl 19 3.3 Workflow „Ölmalerei“ 21 3.4 Workflow „Tuschezeichnung 22 3.5 Workflow „Silhouette“ 22 4 Praktischer Teil 23 4.1 Konkrete Umsetzung 23 4.1.1 Workflow „Ölmalerei“ 24 4.1.2 Workflow „Tuschezeichnung“ 32 4.1.3 Workflow „Silhouette“ 32 4.2 Implementierung eines Automatisierungsprozesses 35 4.3 Anwendung: Karte Dresden 39 4.4 Neural Style Transfer 43 4.4.1 Online-Anwendungen 43 4.4.2 Offline-Implementierung 45 5 Diskussion 51 5.1 Resultate 51 5.1.1 Bildverarbeitung 51 5.1.2 Neural Style Transfer 51 5.2 Ausblick 52 6 Zusammenfassung 52 Literaturverzeichnis 53 / The use of iconographic, pictorial map symbols is very popular for the representation of places of interest in tourist maps as well as for map presentations for children and young people. The term Non-Photorealistic Rendering (NPR) describes a prominent field in computer graphics that deals with the generation of images that are apparently handmade and deliberately do not correspond to the physically correct image of a model. Neural Style Transfer (NST) is another trend topic for imitating a certain style of an artwork. Here, artistic images are created by separating and recombining image content and style. In the context of the present work, a semi-automatic workflow for the creation of iconographic building representations for use in zoomable web maps has been developed and technically implemented in three artistic style variants using image processing tools in the raster-based open source image processing program GIMP, especially with the filter collection G'MIC. In addition, the master thesis demonstrates the potential of deriving iconographic signatures through style transfer using neural networks.:Selbstständigkeitserklärung III Inhaltsverzeichnis 5 Abbildungsverzeichnis 7 Tabellenverzeichnis 8 Abkürzungsverzeichnis 9 1 Einleitung 10 1.1 Motivation 10 1.2 Gliederung der Arbeit 10 2 Literaturstudium 11 2.1 Computergrafik 11 2.2 Non-Photorealistic Rendering 11 2.3 Neural Style Transfer 14 2.3.1 Einleitung 14 2.3.2 Convolutional Neural Network 15 2.3.3 Beschreibung des Algorithmus 17 3 Methodik 19 3.1 Technische Komponenten 19 3.2 Kriterien der Bildauswahl 19 3.3 Workflow „Ölmalerei“ 21 3.4 Workflow „Tuschezeichnung 22 3.5 Workflow „Silhouette“ 22 4 Praktischer Teil 23 4.1 Konkrete Umsetzung 23 4.1.1 Workflow „Ölmalerei“ 24 4.1.2 Workflow „Tuschezeichnung“ 32 4.1.3 Workflow „Silhouette“ 32 4.2 Implementierung eines Automatisierungsprozesses 35 4.3 Anwendung: Karte Dresden 39 4.4 Neural Style Transfer 43 4.4.1 Online-Anwendungen 43 4.4.2 Offline-Implementierung 45 5 Diskussion 51 5.1 Resultate 51 5.1.1 Bildverarbeitung 51 5.1.2 Neural Style Transfer 51 5.2 Ausblick 52 6 Zusammenfassung 52 Literaturverzeichnis 53

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.

V interaktivních aplikacích jsou stíny tradičně zobrazovány s pomocí algoritmu založeným na stínových mapách. Nevýhodou toho algoritmu je, že stínová mapa, reprezentovaná texturou, má pouze omezené rozlišení. To může vést k nepěkným vizuálním artefaktům objevujících se na hranách stínů. Tato práce představuje postup, který je založen na vylepšené deformaci textury. To umožní zobrazit scénu obsahující složité světelné zdroje, zredukovat artefakty na hranicích stínů a také vylepšit kvalitu stínů bez ohledu na typu scény a její konfiguraci.