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Now showing 1 - 6 of 6
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    Efficient Rendering of Local Subsurface Scattering
    (The Eurographics Association and Blackwell Publishing Ltd., 2005) Mertens, Tom; Kautz, Jan; Bekaert, Philippe; Van Reeth, Frank; Seidel, Hans-Peter
    A novel approach is presented to efficiently render local subsurface scattering effects. We introduce an importance sampling scheme for a practical subsurface scattering model. It leads to a simple and efficient rendering algorithm, which operates in image space, and which is even amenable for implementation on graphics hardware. We demonstrate the applicability of our technique to the problem of skin rendering, for which the subsurface transport of light typically remains local. Our implementation shows that plausible images can be rendered interactively using hardware acceleration.
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    Interactive Rendering of Translucent Deformable Objects
    (The Eurographics Association, 2003) Mertens, Tom; Kautz, Jan; Bekaert, Philippe; Seidel, Hans-Peter; Reeth, Frank Van; Philip Dutre and Frank Suykens and Per H. Christensen and Daniel Cohen-Or
    Realistic rendering of materials such as milk, fruits, wax, marble, and so on, requires the simulation of subsurface scattering of light. This paper presents an algorithm for plausible reproduction of subsurface scattering effects. Unlike previously proposed work, our algorithm allows to interactively change lighting, viewpoint, subsurface scattering properties, as well as object geometry. The key idea of our approach is to use a hierarchical boundary element method to solve the integral describing subsurface scattering when using a recently proposed analytical BSSRDF model. Our approach is inspired by hierarchical radiosity with clustering. The success of our approach is in part due to a semi-analytical integration method that allows to compute needed point-to-patch form-factor like transport coefficients efficiently and accurately where other methods fail. Our experiments show that high-quality renderings of translucent objects consisting of tens of thousands of polygons can be obtained from scratch in fractions of a second. An incremental update algorithm further speeds up rendering after material or geometry changes.
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    An Image-Based Radiosity Representation
    (Eurographics Association, 2002) Mertens, Tom; Van Reeth, Frank
    We present a geometry-independent radiosity representation which stems from image-based methodologies. Our image-based representation is inspired by the concept of layered depth images. To construct the radiosity function we render shaded depth images and warp them into the representation. This enables us to alter Keller’s instant radiosity algorithm to a view-independent variant, allowing interactive viewing of complex scenes without relighting every frame. Image warping is done on the host CPU, while graphics hardware is exploited for rendering the images. Our approach differs from the traditional finite element methods since no a priori meshing, nor an explicit form factor evaluation needs to be performed. The geometry independence ensures a reliable rendering time and memory usage, which are more dependent on image resolution rather than scene complexity. It also implies that lighting information is decoupled from scene representation, thereby avoiding the restriction to planar surfaces and issues such as discontinuity meshing.
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    Convolution Shadow Maps
    (The Eurographics Association, 2007) Annen, Thomas; Mertens, Tom; Bekaert, Philippe; Seidel, Hans-Peter; Kautz, Jan; Jan Kautz and Sumanta Pattanaik
    We present Convolution Shadow Maps, a novel shadow representation that affords efficient arbitrary linear filtering of shadows. Traditional shadow mapping is inherently non-linear w.r.t. the stored depth values, due to the binary shadow test. We linearize the problem by approximating shadow test as a weighted summation of basis terms. We demonstrate the usefulness of this representation, and show that hardware-accelerated anti-aliasing techniques, such as tri-linear filtering, can be applied naturally to Convolution Shadow Maps. Our approach can be implemented very efficiently in current generation graphics hardware, and offers real-time frame rates.
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    A Self-Shadow Algorithm for Dynamic Hair using Density Clustering
    (The Eurographics Association, 2004) Mertens, Tom; Kautz, Jan; Bekaert, Philippe; Reeth, Frank Van; Alexander Keller and Henrik Wann Jensen
    Self-shadowing is an important factor in the appearance of hair and fur. In this paper we present a new rendering algorithm to accurately compute shadowed hair at interactive rates using graphics hardware. No constraint is imposed on the hair style, and its geometry can be dynamic. Similar to previously presented methods, a 1D visibility function is constructed for each line of sight of the light source view. Our approach differs from other work by treating the hair geometry as a 3D density field, which is sampled on the fly using simple rasterization. The rasterized fragments are clustered, effectively estimating the density of hair along a ray. Based hereon, the visibility function is constructed. We show that realistic selfshadowing of thousands of individual dynamic hair strands can be rendered at interactive rates using consumer graphics hardware.
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    Texture Transfer Using Geometry Correlation
    (The Eurographics Association, 2006) Mertens, Tom; Kautz, Jan; Chen, Jiawen; Bekaert, Philippe; Durand, Frédo; Tomas Akenine-Moeller and Wolfgang Heidrich
    Texture variation on real-world objects often correlates with underlying geometric characteristics and creates a visually rich appearance. We present a technique to transfer such geometry-dependent texture variation from an example textured model to new geometry in a visually consistent way. It captures the correlation between a set of geometric features, such as curvature, and the observed diffuse texture. We perform dimensionality reduction on the overcomplete feature set which yields a compact guidance field that is used to drive a spatially varying texture synthesis model. In addition, we introduce a method to enrich the guidance field when the target geometry strongly differs from the example. Our method transfers elaborate texture variation that follows geometric features, which gives 3D models a compelling photorealistic appearance.