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Item Enhanced Sphere Tracing(The Eurographics Association, 2014) Keinert, Benjamin; Schäfer, Henry; Korndörfer, Johann; Ganse, Urs; Stamminger, Marc; Andrea GiachettiIn 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.Item Stateless Level of Detail Lighting for Automotive Visualization(The Eurographics Association, 2014) Weber, Christoph; Stamminger, Marc; Andrea GiachettiCar models typically consist of highly specular surfaces including sharp angles. Renderings of such models contain very fine, sharp lighting features, that both make Level-of-Detail switches well visible and result in strong aliasing artifacts. In this paper we address both issues. As Level-of-Detail approach, we apply on-the-fly vertex clustering and introduce a texture coordinate correction to remove popping artifacts, that become visible during mesh simplification. By replacing vertex normals with texture normals, we can provide stable lighting features, even if the underlying mesh changes. To prevent aliasing effects on specular highlights, we then apply a variant of LEAN mapping (linear efficient antialiased normal mapping). We observe that LEAN mapping cannot be applied directly, because in our scenario we need to filter object space normals, as we have no presupposed tangent-space availeble. We therefore create a per-texel tangent space from an object space MIP normal, thus retaining the benefits of a 2D distribution without a preexisting tangent space. Both approaches in combination, allow us to render highly reflective, detailed models with continuous level of detail and anti-aliased lighting, at the price of moderately increased memory consumption and render time.