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.

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

Image based lighting, (IBL), is a computer graphics technique for creating photorealistic renderings of synthetic objects such that they can be placed into real world scenes. IBL has been widely recognized and is today used in commercial production pipelines. However, the current techniques only use illumination captured at a single point in space. This means that traditional IBL cannot capture or recreate effects such as cast shadows, shafts of light or other important spatial variations in the illumination. Such lighting effects are, in many cases, artistically created or are there to emphasize certain features, and are therefore a very important part of the visual appearance of a scene. This thesis and the included papers present methods that extend IBL to allow for capture and rendering with spatially varying illumination. This is accomplished by measuring the light field incident onto a region in space, called an Incident Light Field, (ILF), and using it as illumination in renderings. This requires the illumination to be captured at a large number of points in space instead of just one. The complexity of the capture methods and rendering algorithms are then significantly increased. The technique for measuring spatially varying illumination in real scenes is based on capture of High Dynamic Range, (HDR), image sequences. For efficient measurement, the image capture is performed at video frame rates. The captured illumination information in the image sequences is processed such that it can be used in computer graphics rendering. By extracting high intensity regions from the captured data and representing them separately, this thesis also describes a technique for increasing rendering efficiency and methods for editing the captured illumination, for example artificially moving or turning on and of individual light sources.

<p>The aim with this thesis is to develop a plugin; Lovefish, for the purpose of allowing non-realistic renderings (NPR) for visualisation in Newtek Lightwave3D. The main purpose with Lovefish is to offer textured tones, something that has not been offered before by any previously existing shader for Lightwav3D. The textured tones are a substantially widening of what is possible to imitate in the field of classical art techniques. Among others has a number of SIGGRAPH papers has been the foundation and a source of inspiration for what has been achieve in this project. Further has this thesis treated a number of questions: what is non-photorealistic rendering is and how it works; an overview of the Lightwave3Ds software development kit (SDK).</p>

The aim with this thesis is to develop a plugin; Lovefish, for the purpose of allowing non-realistic renderings (NPR) for visualisation in Newtek Lightwave3D. The main purpose with Lovefish is to offer textured tones, something that has not been offered before by any previously existing shader for Lightwav3D. The textured tones are a substantially widening of what is possible to imitate in the field of classical art techniques. Among others has a number of SIGGRAPH papers has been the foundation and a source of inspiration for what has been achieve in this project. Further has this thesis treated a number of questions: what is non-photorealistic rendering is and how it works; an overview of the Lightwave3Ds software development kit (SDK).

This thesis describes the development of a system for the procedural generation and painterly rendering of trees. Specifically, the rendered trees are modeled after those found in the oil landscape paintings of 19th century French painter Camille Corot. The rendering system, which is a combination of MEL-scripted Maya tools and Renderman shaders, facilitates the creation of still images that look convincingly painterly, as well as 3D animations with temporal coherence. Brush stroke properties are animated based on distance from the camera, so that traditional painting techniques for representing depth are incorporated into the computer-generated animations. During the development process, the system was generalized to apply to other structures, such as grass and rocks, and allows for the creation and rendering of entire landscapes. Several example animations were created with the system to demonstrate the ideas developed during the process and the quality of the results.

Research and development of Non-Photorealistic Rendering algorithms has recently moved towards the use of computer vision algorithms to extract image features. The feature representation capabilities of image moments could be used effectively for the selection of brush-stroke characteristics for painterly-rendering applications. This technique is based on the estimation of local geometric features from the intensity distribution in small windowed images to obtain the brush size, color and direction. This thesis proposes an improvement of this method, by additionally extracting the connected components so that the adjacent regions of similar color are grouped for generating large and noticeable brush-stroke images. An iterative coarse-to-fine rendering algorithm is developed for painting regions of varying color frequencies. Improvements over the existing technique are discussed with several examples.

In applications such as architecture, early design sketches containing accurate line drawings often mislead the target audience [Schumann et al. 1996]. Approximate human-drawn sketches are typically accepted as a better way of demonstrating fundamental design concepts. To this end I have designed an algorithm that creates lines that perceptually resemble human-drawn lines. My algorithm works directly with input point data and a physically–based mathematical model of human arm movement. Further, the algorithm does not rely on a database of human drawn lines, nor does it require any input other than the end points of the lines to generate a line of arbitrary length. The algorithm will generate any number of aesthetically pleasing and natural looking lines, where each one is unique. The algorithm was developed by conducting various user studies on human drawn pencil line sketches, and analyzing the lines to produce basic heuristics. I found that an observational analysis of human lines made a bigger impact on the algorithm than a statistical analysis. A further study shows that the algorithm produces lines that are perceptually indistinguishable from straight hand-drawn pencil lines.

The creation of expressive styles for digital art is one of the primary goals in non-photorealistic rendering. In this paper, we introduce a swarm-based multi-agent system that is capable of producing expressive imagery through the use of multiple digital images. At birth, agents in our system are assigned a digital image that represents their 'aesthetic ideal'. As agents move throughout a digital canvas they try to 'realize' their ideal by modifying the pixels in the digital canvas to be closer to the pixels in their aesthetic ideal. When groups of agents with different aesthetic ideals occupy the same canvas, a new image is created through the convergence of their competing aesthetic goals. We use our system to explore the concepts and techniques from a number of Modern Art movements and to create an interactive media installation. The simple implementation and effective results produced by our system makes a compelling argument for more research using swarm-based multi-agent systems for non-photorealistic rendering. / Graduate