Design and implementation of an automated workflow to provide a zoomable web mapping application using artistic styles

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 9