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Now showing 1 - 4 of 4
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    Faster Ray-Traced Shadows for Hybrid Rendering of Fully Dynamic Scenes by Pre-BVH Culling
    (The Eurographics Association, 2015) Selgrad, Kai; Müller, Jonas; Stamminger, Marc; Andrea Giachetti and Silvia Biasotti and Marco Tarini
    With ever increasing ray traversal and hierarchy construction performance the application of ray tracing to problems often tackled by rasterization-based algorithms is becoming a viable alternative. This is especially desirable as the ground truth for these algorithms is often determined by using ray tracing and thus directly applying it is the simplest way to generate images satisfying the reference. In this paper we propose a very efficient pre-process to speed up the construction and traversal of sub-optimal, but fast-to-build hierarchies used for interactive ray tracing and show how it can be applied to shadow rays in a hybrid environment, where ray tracing is used to sample area lights for scene positions found and shaded via rasterization.
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    Practical Offline Rendering of Woven Cloth
    (The Eurographics Association, 2016) Nelson, Vidar; McEvoy, Peter M.; Fratarcangeli, Marco; Giovanni Pintore and Filippo Stanco
    The techniques for rendering woven cloth employed in a production environment often neglect many of the structural features of the fabric, as well as light-scattering processes that occur in the yarn. Research in this area has progressed, and new promising methods have recently been proposed; however, many of these are not applied in practice due to their inherent complexities. In this paper, we develop and implement a shader for woven cloth that fulfills some of the needs of a production environment using an existing model for simulating the interaction with light. The shader delivers highly realistic results that are comparable, and in some cases superior, to current methods used in a real production environment. We enriched and validated the proposed framework by using direct feedback from a large company that produces images of furniture using computer graphics. The results demonstrate that our shader accurately simulates the appearance of certain types of woven cloth, showing reflections that are not present in other methods in current use. Our shader is easy to integrate in existing pipelines, flexible because it provides the artist with enough parameters to recreate many different types of fabric, and generic for the domain of woven cloth because it is able to accept as input widely used WIF files, which describe weave patterns as well as yarn specific parameters.
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    Enhanced Sphere Tracing
    (The Eurographics Association, 2014) Keinert, Benjamin; Schäfer, Henry; Korndörfer, Johann; Ganse, Urs; Stamminger, Marc; Andrea Giachetti
    In this paper we present several performance and quality enhancements to classical sphere tracing: First, we propose a safe, over-relaxation-based method for accelerating sphere tracing. Second, a method for dynamically preventing self-intersections upon converting signed distance bounds enables controlling precision and rendering performance. In addition, we present a method for significantly accelerating the sphere tracing intersection test for convex objects that are enclosed in convex bounding volumes. We also propose a screen-space metric for the retrieval of a good intersection point candidate, in case sphere tracing does not converge thus increasing rendering quality without sacrificing performance. Finally, discontinuity artifacts common in sphere tracing are reduced using a fixed-point iteration algorithm. We demonstrate complex scenes rendered in real-time with our method. The methods presented in this paper have more universal applicability beyond rendering procedurally generated scenes in real-time and can also be combined with path-tracing-based global illumination solutions.
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    Kernel-Reflection Sequences
    (The Eurographics Association, 2016) Szécsi, László; Bendefy, Zoltán; Kacsó, Ágota; Giovanni Pintore and Filippo Stanco
    Complex geometries, like those of plants, rocks, terrain, or even clouds are challenging to model in a way that allows for real-time rendering but does not make concessions in terms of visible detail. In this paper we propose a procedural modeling approach, called KRS, or kernel-reflection sequences, inspired by iterated function systems. The model is composed of kernel geometries defined by signed distance functions, and reflection transformations that multiply them. We show that a global distance function can be evaluated over this structure without recursion, allowing for the implementation of real-time sphere tracing on parallel hardware. We also show how the algorithm readily delivers continuous level-of-detail and minification filtering. We propose several techniques to enhance modeling freedom and avoid conspicuous symmetries. Most importantly, we extend sphere tracing to conformally transformed geometries. We also propose a GPU load balancing scheme for best utilization of computing power. To prove that the model can be used to realize various natural phenomena in uncompromising detail and extents, without obvious clues of symmetry, we render aquatic and terrestrial surface formations and vegetation in real-time.