@article{lipp2011a, title = "Interactive Modeling of City Layouts using Layers of Procedural Content", author = "Markus Lipp and Daniel Scherzer and Peter Wonka and Michael Wimmer", year = "2011", abstract = "In this paper, we present new solutions for the interactive modeling of city layouts that combine the power of procedural modeling with the flexibility of manual modeling. Procedural modeling enables us to quickly generate large city layouts, while manual modeling allows us to hand-craft every aspect of a city. We introduce transformation and merging operators for both topology preserving and topology changing transformations based on graph cuts. In combination with a layering system, this allows intuitive manipulation of urban layouts using operations such as drag and drop, translation, rotation etc. In contrast to previous work, these operations always generate valid, i.e., intersection-free layouts. Furthermore, we introduce anchored assignments to make sure that modifications are persistent even if the whole urban layout is regenerated. ", month = apr, journal = "Computer Graphics Forum (Proceedings EG 2011)", volume = "30", number = "2", issn = "0167-7055", pages = "345--354", URL = "https://www.cg.tuwien.ac.at/research/publications/2011/lipp2011a/", } @phdthesis{lipp_markus-2010-DAC, title = "Direct Artist Control for Procedural Content Generation of Urban Environments", author = "Markus Lipp", year = "2010", abstract = "Creating 3D digital assets of urban environments is a challenging task, requiring a significant amount of manual labor. To automate parts of this process, many procedural modeling methods to automatically create buildings, plants or entire cities were introduced. The main advantage of such methods compared to manual methods is the ability to create large amounts of assets using just a few parameters as input data. However, the main disadvantage is the difficulty to control or predict the output of such methods. Direct controllability is especially important for artists enabling them to model the output to their vision or requirements. Therefore, the main goal of this thesis is combining the direct control provided by manual methods with the power of procedural modeling. To achieve this, several new methods and paradigms bringing direct and visual artist control to procedural generation of urban environments are contributed in this thesis. These include a method enabling a visual design process for building grammars, as well as methods providing direct artist control for architecture generation algorithms. To model whole cities, we introduce a layering system for urban layouts based on graph cut, contributing the ability to perform direct and persistent changes to a procedurally generated city. Additionally, the concept of anchored assignments is introduced, enabling direct control of parameter distributions on cities. Finally, as real-time performance of generation algorithms is paramount if they are to be used in a production setting, we introduce an algorithm able to parallelize the work of L-system generation to thousands of processors.", month = oct, address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", keywords = "Procedural Modeling, Urban Layouts, Interactive Control", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/lipp_markus-2010-DAC/", } @article{LIPP-2010-PGMS, title = "Parallel Generation of Multiple L-Systems", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2010", abstract = "This paper introduces a solution to compute L-systems on parallel architectures like GPUs and multi-core CPUs. Our solution can split the derivation of the L-system as well as the interpretation and geometry generation into thousands of threads running in parallel. We introduce a highly parallel algorithm for L-system evaluation that works on arbitrary L-systems, including parametric productions, context sensitive productions, stochastic production selection, and productions with side effects. This algorithm is further extended to allow evaluation of multiple independent L-systems in parallel. In contrast to previous work, we directly interpret the productions defined in plain-text, without requiring any compilation or transformation step (e.g., into shaders). Our algorithm is efficient in the sense that it requires no explicit inter-thread communication or atomic operations, and is thus completely lock free.", month = oct, issn = "0097-8493", journal = "Computers & Graphics", number = "5", volume = "34", pages = "585--593", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/LIPP-2010-PGMS/", } @mastersthesis{scharl-master-thesis, title = "Artist-Controlled Modeling of Urban Environments", author = "Johannes Scharl", year = "2010", abstract = "Creating large-scale virtual environments for interactive applications such as computer games poses a demanding challenge for computer graphics. Urban environments are usually hand-crafted by artists using commercial 3D modeling software. For today’s detail-rich games, this becomes less and less feasible. Procedural modeling techniques strive to help artists to create virtual worlds in less time. In this thesis, I present a system that helps artists and game designers to plan, layout and model urban environments for games and other media. Methods are described to create street networks manually and procedurally and to edit them interactively at any time in the development process. A stable street tessellation technique is employed that is able to represent street segments as well as crossings connecting an arbitrary number of streets and that adapts to the underlying terrain. Furthermore, I propose a constraint based method to automatically populate a city with buildings from a set of existing building models. ", month = jul, address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/scharl-master-thesis/", } @WorkshopTalk{ilcik-2011-pmous, title = "Procedural Modeling of Urbanistic Scenes", author = "Martin Il\v{c}\'{i}k and Markus Lipp and Johannes Scharl and Michael Wimmer", year = "2010", abstract = "The aim of the GameWorld project was the procedural generation of cities and buildings on different levels of control, from manual to fully automatic modeling. Target applications included mainly computer games, virtual reality applications and other digital content creation scenarios for entertainment industry, architectural, historical and archaeological visualizations, and much more.", month = jun, event = "Austrian-Russian Joint Seminar - Visual Computing in Fundamental, Academic and Applied Science and Research", location = "Vienna, Austria", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/ilcik-2011-pmous/", } @inproceedings{ilcik-2010-ps, title = "Procedural Skeletons: Kinematic Extensions to CGA-Shape Grammars", author = "Martin Il\v{c}\'{i}k and Stefan Fiedler and Werner Purgathofer and Michael Wimmer", year = "2010", abstract = "Procedural modeling for architectural scenes was as yet limited to static objects only. We introduce a novel extension layer for shape grammars which creates a skeletal system for posing and interactive manipulation of generated models. Various models can be derived with the same set of parametrized rules for geometric operations. Separation of geometry generation and pose synthesis improves design efficiency and reusability. Moreover, by formal analysis of production rules we show how to efficiently update complex kinematic hierarchies created by the skeletons, allowing state-of-the-art interactive visual rule editing.", month = may, isbn = "978-80-223-2644-5", publisher = "Comenius University, Bratislava", booktitle = "Proceedings of the Spring Conference on Computer Graphics 2010", pages = "177--184", keywords = "procedural modeling, shape grammars, architecture, skeletal animation", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/ilcik-2010-ps/", } @inproceedings{Habel-2010-EIN, title = "Efficient Irradiance Normal Mapping", author = "Ralf Habel and Michael Wimmer", year = "2010", abstract = "Irradiance normal mapping is a method to combine two popular techniques, light mapping and normal mapping, and is used in games such as Half-Life 2 or Halo 3. This combination allows using low-resolution light caching on surfaces with only a few coefficients which are evaluated by normal maps to render spatial high-frequency changes in the lighting. Though there are dedicated bases for this purpose such as the Half-Life 2 basis, higher order basis functions such as quadratic Spherical Harmonics are needed for an accurate representation. However, a full spherical basis is not needed since the irradiance is stored on the surface of a scene. In order to represent the irradiance signals efficiently, we propose a novel polynomial, hemispherically orthonormal basis function set that is specifically designed to carry a directional irradiance signal on the hemisphere and which makes optimal use of the number of coefficients. To compare our results with previous work, we analyze the relations and attributes of previously proposed basis systems and show that 6 coefficients are sufficient to accurately represent an irradiance signal on the hemisphere. To create the necessary irradiance signals, we use Spherical Harmonics as an intermediate basis due to their fast filtering capabilities.", month = feb, isbn = "978-1-60558-939-8", publisher = "ACM", location = "Washington D.C.", booktitle = "Proceedings of the ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games 2010", pages = "189--195", keywords = "irradiance, real-time rendering, normal mapping, lightmap", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/Habel-2010-EIN/", } @studentproject{unterguggenberger-2010-cmph, title = "Connected meshes for procedural humans", author = "Johannes Unterguggenberger", year = "2010", keywords = "shape grammars, connectivity, procedural", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/unterguggenberger-2010-cmph/", } @studentproject{kuehtreiber-2010-ikph, title = "Inverse Kinematics for Shape Grammars", author = "Patrick K\"{u}htreiber", year = "2010", abstract = "In this project I describe the implementation of a solver of the Inverse Kinematic (IK) problem in an environment using shape grammar based on CGA Shape. There exists a number of different algorithms for this problem, however, this report describes only the cyclic coordinate descent (CCD) in more detail as this is the method we implemented. The implementation enabels the positioning of a certain shape so that it touches a user-specified target point. The implemented algorithm rotates the shapes until the end effector is at the desired position.", keywords = "procedural modeling, inverse kinematics", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/kuehtreiber-2010-ikph/", } @studentproject{NIEDERREITER-2010-SIM, title = "Similarity Detection for Urban Modeling", author = "Christian Niederreiter", year = "2010", abstract = "This application is a basic graphical user interface framework for experiments on architectural meshes. The meshes are displayed in the form of wires or polygons inside the window and can be modified using custom controls in the control box at the left border of the window. By the support of OGRE3D, arbitrary information concerning the displayed meshes can be overlaid at 3D coordinates. The mesh can be translated and rotated using the mouse and keyboard.", keywords = "urban modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/NIEDERREITER-2010-SIM/", } @studentproject{RADAX-2010-LOD, title = "Levels of Detail for Procedural Modeling", author = "Ingo Radax", year = "2010", abstract = "The Cga-LoD program is used to create LoD models out of models created with Markus Lipp's Cga program. The LoDs are based on bounding boxes, rather than mesh simplification. The Cga program creates architectural models based on hierarchical rules. The Cga-LoD program now uses the hierarchy of each model to create the LoD models. Basically parts of the hierarchy will be replaced by oriented bounding boxes enclosing the geometry of this parts. This bounding boxes will them be texturized and used instead of the original geometry.", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/RADAX-2010-LOD/", } @studentproject{dusberger-2010-msm, title = "Mesh-Subdivision Methods in CGA Shape Grammars", author = "Frederico Dusberger", year = "2010", abstract = "This report describes the application of mesh-subdivision algorithms in the context of CGA shape, a shape grammar for Computer Generated Architecture. Constituting a procedural modeling approach, CGA shape allows the creation of models under moderate effort, which can furthermore be varied easily by the possibility to parametrize the rules of CGA shape. At the Vienna University of Technology a CGA shape implementation is being designed and extended by a skeleton system, allowing an easier variation of poses for humanoid models. In this report we follow this idea and want to further extend CGA shape by meshsubdivision in order to achieve a higher quality and complexity in the resulting models. We discuss mesh-subdivision in general and evaluate the results of an implementation in the existing software system of the Vienna University of Technology.", keywords = "mesh subdivision, shape grammars, procedural modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2010/dusberger-2010-msm/", } @inproceedings{LIPP-2009-PGL, title = "Parallel Generation of L-Systems", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2009", abstract = "This paper introduces a solution to compute L-systems on parallel architectures like GPUs and multi-core CPUs. Our solution can split the derivation of the L-system as well as the interpretation and geometry generation into thousands of threads running in parallel. We introduce a highly parallel algorithm for L-system evaluation that works on arbitrary L-systems, including parametric productions, context sensitive productions, stochastic production selection, and productions with side effects. Further we directly interpret the productions defined in plain-text, without requiring any compilation or transformation step (e.g., into shaders). Our algorithm is efficient in the sense that it requires no explicit inter-thread communication or atomic operations, and is thus completely lock free.", month = nov, isbn = "978-3980487481", location = "Braunschweig", editor = "Marcus Magnor, Bodo Rosenhahn, Holger Theisel", booktitle = "Vision, Modeling, and Visualization Workshop (VMV) 2009 ", pages = "205--214", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/LIPP-2009-PGL/", } @WorkshopTalk{Purgathofer-2009-rus, title = "Interactive Visual Editing of Grammars for Procedural Architecture", author = "Werner Purgathofer and Markus Lipp", year = "2009", month = oct, event = "Visual Computing in Fundamental, Academic and Applied Science and Research", location = "Moskau, Russia", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/Purgathofer-2009-rus/", } @misc{LIPP-2009-PGL2, title = "Parallel Generation of L-Systems", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2009", abstract = "In this work we investigate whether it is possible to efficiently evaluate one of the most classical procedural modeling primitives, L-systems, directly on parallel architectures, exemplified by current GPUs and multi-core CPUs. The main motivation is to enable interactive editing of large L-systems by designers, therefore it is important to speed up the computation of L-systems in order to achieve low response times.", month = aug, location = "New Orleans, LA", event = "High-Performance Graphics 2009", Conference date = "Poster presented at High-Performance Graphics 2009 (2009-08-01--2009-08-03)", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/LIPP-2009-PGL2/", } @article{Habel_09_PGT, title = "Physically Guided Animation of Trees", author = "Ralf Habel and Alexander Kusternig and Michael Wimmer", year = "2009", abstract = "This paper presents a new method to animate the interaction of a tree with wind both realistically and in real time. The main idea is to combine statistical observations with physical properties in two major parts of tree animation. First, the interaction of a single branch with the forces applied to it is approximated by a novel efficient two step nonlinear deformation method, allowing arbitrary continuous deformations and circumventing the need to segment a branch to model its deformation behavior. Second, the interaction of wind with the dynamic system representing a tree is statistically modeled. By precomputing the response function of branches to turbulent wind in frequency space, the motion of a branch can be synthesized efficiently by sampling a 2D motion texture. Using a hierarchical form of vertex displacement, both methods can be combined in a single vertex shader, fully leveraging the power of modern GPUs to realistically animate thousands of branches and ten thousands of leaves at practically no cost.", month = mar, journal = "Computer Graphics Forum (Proceedings EUROGRAPHICS 2009)", volume = "28", number = "2", issn = "0167-7055", pages = "523--532", keywords = "Animation, Physically Guided animation, Vegetation, Trees", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/Habel_09_PGT/", } @studentproject{fiedler-2009-php, title = "Procedural Human Posing Using CGA Grammars", author = "Stefan Fiedler", year = "2009", abstract = "This report presents a grammar for the procedural modeling of humanoid characters and poses based on CGA shape, a shape grammar for computer generated architecture. Various models can be derived with the same set of parametrized rules for geometric operations, and include a skeletal system for posing. The main part of this report defines basic rules and their effect on shapes and skeletons and discusses the results of an actual implementation of the grammar with examples.", keywords = "shape grammars, computer animation, character modeling, procedural modeling, computational geometry", URL = "https://www.cg.tuwien.ac.at/research/publications/2009/fiedler-2009-php/", } @article{LIPP-2008-IEV, title = "Interactive Visual Editing of Grammars for Procedural Architecture", author = "Markus Lipp and Peter Wonka and Michael Wimmer", year = "2008", abstract = "We introduce a real-time interactive visual editing paradigm for shape grammars, allowing the creation of rulebases from scratch without text file editing. In previous work, shape-grammar based procedural techniques were successfully applied to the creation of architectural models. However, those methods are text based, and may therefore be difficult to use for artists with little computer science background. Therefore the goal was to enable a visual workflow combining the power of shape grammars with traditional modeling techniques. We extend previous shape grammar approaches by providing direct and persistent local control over the generated instances, avoiding the combinatorial explosion of grammar rules for modifications that should not affect all instances. The resulting visual editor is flexible: All elements of a complex state-of-the-art grammar can be created and modified visually.", month = aug, journal = "ACM Transactions on Graphics", volume = "27", number = "3", note = "Article No. 102", issn = "0730-0301", doi = "10.1145/1360612.1360701", pages = "102:1--10", keywords = "procedural modeling, shape grammars, architectural modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/LIPP-2008-IEV/", } @mastersthesis{GEBHART-2008-AGV, title = "Automatisches Generieren von 3D-Stra{\ss}ensystemen", author = "Gernot Gebhart", year = "2008", abstract = "In dieser Arbeit geht es um die Generierung von 3D Geometrie f\"{u}r gro{\ss}e Stra{\ss}ensysteme.", month = mar, address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", keywords = "3d street modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2008/GEBHART-2008-AGV/", } @mastersthesis{LIPP-2007-CGA, title = "Interactive Computer Generated Architecture", author = "Markus Lipp", year = "2007", abstract = "The creation of visually convincing architectural models using traditional modeling methods is a labor intensive task. Procedural modeling techniques strive to reduce the manual work an artist has to perform when modeling architecture. In previous work, those techniques were successfully applied to the creation of architecture. However, previous methods have a limited usability, as they are based on text editing. This makes modeling unintuitive and diminishes the advantages of procedural modeling. Therefore, methods to interactively create procedural architecture, using a graphical user interface, are explored in this thesis. As interactivity also requires real-time rendering performance, methods to accelerate the generation of architecture are investigated. Further, the thesis provides a detailed report on previous procedural architecture generation techniques.", address = "Favoritenstrasse 9-11/E193-02, A-1040 Vienna, Austria", school = "Institute of Computer Graphics and Algorithms, Vienna University of Technology ", keywords = "computer generated architecture, procedural modeling", URL = "https://www.cg.tuwien.ac.at/research/publications/2007/LIPP-2007-CGA/", }