Search Results

Now showing 1 - 7 of 7
  • Item
    Freeform Shadow Boundary Editing
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Mattausch, Oliver; Igarashi, Takeo; Wimmer, Michael; I. Navazo, P. Poulin
    We present an algorithm for artistically modifying physically based shadows. With our tool, an artist can directly edit the shadow boundaries in the scene in an intuitive fashion similar to freeform curve editing. Our algorithm then makes these shadow edits consistent with respect to varying light directions and scene configurations, by creating a shadow mesh from the new silhouettes. The shadow mesh helps a modified shadow volume algorithm cast shadows that conform to the artistic shadow boundary edits, while providing plausible interaction with dynamic environments, including animation of both characters and light sources. Our algorithm provides significantly more fine-grained local and direct control than previous artistic light editing methods, which makes it simple to adjust the shadows in a scene to reach a particular effect, or to create interesting shadow shapes and shadow animations. All cases are handled with a single intuitive interface, be it soft shadows, or (self-)shadows on arbitrary receivers.
  • Item
    Non-Sampled Anti-Aliasing
    (The Eurographics Association, 2013) Auzinger, Thomas; Musialski, Przemyslaw; Preiner, Reinhold; Wimmer, Michael; Michael Bronstein and Jean Favre and Kai Hormann
    In this paper we present a parallel method for high-quality edge anti-aliasing in rasterization. In contrast to traditional graphics hardware methods, which rely on massive oversampling to combat aliasing issues, we evaluate a closed-form solution of the associated prefilter convolution. This enables the use of a wide range of filter functions with arbitrary kernel sizes, as well as general shading methods such as texture mapping or complex illumination models. Due to the use of analytic solutions, our results are exact in the mathematical sense and provide objective ground-truth for other anti-aliasing methods and enable the rigorous comparison of different models and filters. An efficient implementation on general purpose graphics hardware is discussed and several comparisons to existing techniques and of various filter functions are given.
  • Item
    Analytic Visibility on the GPU
    (The Eurographics Association and Blackwell Publishing Ltd., 2013) Auzinger, Thomas; Wimmer, Michael; Jeschke, Stefan; I. Navazo, P. Poulin
    This paper presents a parallel, implementation-friendly analytic visibility method for triangular meshes. Together with an analytic filter convolution, it allows for a fully analytic solution to anti-aliased 3D mesh rendering on parallel hardware. Building on recent works in computational geometry, we present a new edge-triangle intersection algorithm and a novel method to complete the boundaries of all visible triangle regions after a hidden line elimination step. All stages of the method are embarrassingly parallel and easily implementable on parallel hardware. A GPU implementation is discussed and performance characteristics of the method are shown and compared to traditional sampling-based rendering methods.
  • Item
    Inverse-Procedural Methods for Urban Models
    (The Eurographics Association, 2013) Musialski, Przemyslaw; Wimmer, Michael; Vincent Tourre and Gonzalo Besuievsky
    Procedural modeling is an elegant and fast way to generate huge complex and realistically looking urban sites. Due to its generative nature it can also be referred to as forward-procedural modeling. Its major drawback is the usually quite complicated way of control. To overcome this difficulty a novel modeling paradigm has been introduced: it is commonly referred to as inverse procedural modeling, and its goal is to generate compact procedural descriptions of existing models-in the best case in an automatic manner as possible. These compact procedural representations can be used as a source for the synthesis of identical or similar objects, applied in various simulations and other studies of urban environments. We believe that this technology is still a widely unexplored ground and that it will prove itself as a very important tool in the reconstruction process. In this paper we sketch how inverse procedural modeling can be applied in the urban modeling field.
  • Item
    Seamless Texturing of Archaeological Data
    (The Eurographics Association, 2013) Birsak, Michael; Musialski, Przemyslaw; Arikan, Murat; Wimmer, Michael; -
    In this paper we propose a framework for out-of-core real-time rendering of high-quality textured archaeological data-sets. Our input is a triangle mesh and a set of calibrated and registered photographs. Our system performs the actual mapping of the photos to the mesh for high-quality reconstructions, which is a task referred to as the labeling problem. Another problem of such mappings are seams that arise on junctions between triangles that contain information from different photos. These are are approached with blending methods, referred to as leveling. We address both problems and introduce a novel labeling approach based on occlusion detection using depth maps that prevents texturing of parts of the model with images that do not contain the expected region. Moreover, we propose an improved approach for seam-leveling that penalizes too large values and helps to keep the resulting colors in a valid range. For highperformance visualization of the 3D models with a huge amount of textures, we make use of virtual texturing, and present an application that generates the needed texture atlas in significantly less time than existing scripts. Finally, we show how the mentioned components are integrated into a visualization application for digitized archaeological site.
  • Item
    Challenges and Ideas in Procedural Modeling of Interiors
    (The Eurographics Association, 2013) Ilcik, Martin; Wimmer, Michael; Vincent Tourre and Gonzalo Besuievsky
    While the creation of convincing cityscapes from the outside is already possible, there is a lack of robust and efficient techniques for modeling the interior of buildings. In particular, we focus on challenges for the subdivision of the interior space into rooms and for placement of furniture in those rooms.
  • Item
    Sampled and Analytic Rasterization
    (The Eurographics Association, 2013) Auzinger, Thomas; Wimmer, Michael; Michael Bronstein and Jean Favre and Kai Hormann
    In this poster we present an overview of exact anti-aliasing (AA) methods in rasterization. In contrast to the common supersampling approaches for visibility AA (e.g. MSAA) or both visibility and shading AA (e.g. SSAA, decoupled sampling), prefiltering provides the mathematically exact solution to the aliasing problem. Instead of averaging a set a supersamples, the input data is convolved with a suitable low-pass filter before sampling is applied. Recent work showed that for both visibility signals and simple shading models, a closed-form solution to the convolution integrals can be found. As our main contribution, we present a classification of both sample-based and analytic AA approaches for rasterization and analyse their strengths and weaknesses.