EG2015

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https://diglib.eg.org/handle/10.2312/12086

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Browsing EG2015 by Subject "and texture"

Now showing 1 - 7 of 7
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    Adaptive LightSlice for Virtual Ray Lights
    (The Eurographics Association, 2015) Frederickx, Roald; Bartels, Pieterjan; Dutré, Philip; B. Bickel and T. Ritschel
    We speed up the rendering of participating media with Virtual Ray Lights (VRLs) by clustering them in a preprocessing step. A subset of representative VRLs is then sampled from the clustering, which is used for the final rendering. By performing a full variance analysis, we can explicitly estimate the convergence rate of the rendering process and automatically find the locally ideal number of clusters to maximize efficiency. Overall, we report speed-up factors ranging from 13 to 16 compared to unclustered rendering.
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    Compressive Image Reconstruction in Reduced Union of Subspaces
    (The Eurographics Association and John Wiley & Sons Ltd., 2015) Miandji, Ehsan; Kronander, Joel; Unger, Jonas; Olga Sorkine-Hornung and Michael Wimmer
    We present a new compressed sensing framework for reconstruction of incomplete and possibly noisy images and their higher dimensional variants, e.g. animations and light-fields. The algorithm relies on a learning-based basis representation. We train an ensemble of intrinsically two-dimensional (2D) dictionaries that operate locally on a set of 2D patches extracted from the input data. We show that one can convert the problem of 2D sparse signal recovery to an equivalent 1D form, enabling us to utilize a large family of sparse solvers. The proposed framework represents the input signals in a reduced union of subspaces model, while allowing sparsity in each subspace. Such a model leads to a much more sparse representation than widely used methods such as K-SVD. To evaluate our method, we apply it to three different scenarios where the signal dimensionality varies from 2D (images) to 3D (animations) and 4D (light-fields). We show that our method outperforms state-of-the-art algorithms in computer graphics and image processing literature.
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    Exploiting the Potential of Image Based Crowd Rendering
    (The Eurographics Association, 2015) Izquierdo, Maria; Beacco, Alejandro; Pelechano, Nuria; Andujar, Carlos; B. Solenthaler and E. Puppo
    Per-joint impostors have been used to achieve high performance when rendering thousands of agents, while still allowing us to blend animation. This provides interactively animated crowds and reduces the memory footprint compared to classic impostors. In this poster we exploit the potential of per joint impostors to further increase both visual quality and performance. The CAVAST framework for crowd simulation and rendering has been used to quantitatively evaluate our improvements with the profiling tools that it provides. Since different applications will have different requirements in terms of performance vs. visual quality, we have extended CAVAST with a new user interface to ease this process.
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    High-Quality Shadows for Streaming Terrain Rendering
    (The Eurographics Association, 2015) Chajdas, Matthäus G.; Reichl, Florian; Dick, Christian; Westermann, Rüdiger; B. Bickel and T. Ritschel
    Rendering of large, detailed 3D terrains on commodity hardware has become possible through the use of raycasting, data caching and prefetching. Adding dynamic shadows as they appear during a day-night cycle remais a challenge however, because shadow rendering requires access to the entire terrain, invalidating data streaming strategies. In this work we present a novel, practicable shadow rendering approach which distinguishes between near- and precomputed far-shadows to significantly reduce data access and runtime costs. While near-shadows are raytraced using the current cache content, far-shadows are precomputed and stored in a very compact format requiring approximately 3 bit per height-map sample for an entire day-night cycle.
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    IlluminationCut
    (The Eurographics Association and John Wiley & Sons Ltd., 2015) Bus, Norbert; Mustafa, Nabil H.; Biri, Venceslas; Olga Sorkine-Hornung and Michael Wimmer
    We present a novel algorithm, IlluminationCut, for rendering images using the many-lights framework. It handles any light source that can be approximated with virtual point lights (VPLs) as well as highly glossy materials. The algorithm extends the Multidimensional Lightcuts technique by effectively creating an illumination-aware clustering of the product-space of the set of points to be shaded and the set of VPLs. Additionally, the number of visibility queries for each product-space cluster is reduced by using an adaptive sampling technique. Our framework is flexible and achieves around 3 - 6 times speedup over previous state-of-the-art methods.
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    Interactive HDR Environment Map Capturing on Mobile Devices
    (The Eurographics Association, 2015) Kán, Peter; B. Bickel and T. Ritschel
    Real world illumination, captured by digitizing devices, is beneficial to solve many problems in computer graphics. Therefore, practical methods for capturing this illumination are of high interest. In this paper, we present a novel method for capturing environmental illumination by a mobile device. Our method is highly practical as it requires only a consumer mobile phone and the result can be instantly used for rendering or material estimation.We capture the real light in high dynamic range (HDR) to preserve its high contrast. Our method utilizes the moving camera of a mobile phone in auto-exposure mode to reconstruct HDR values. The projection of the image to the spherical environment map is based on the orientation of the mobile device. Both HDR reconstruction and projection run on the mobile GPU to enable interactivity. Moreover, an additional image alignment step is performed. Our results show that the presented method faithfully captures the real environment and that the rendering with our reconstructed environment maps achieves high quality, comparable to reality.
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    Partitioned Shadow Volumes
    (The Eurographics Association and John Wiley & Sons Ltd., 2015) Gerhards, Julien; Mora, Frédéric; Aveneau, Lilian; Ghazanfarpour, Djamchid; Olga Sorkine-Hornung and Michael Wimmer
    Real-time shadows remain a challenging problem in computer graphics. In this context, shadow algorithms generally rely either on shadow mapping or shadow volumes. This paper rediscovers an old class of algorithms that build a binary space partition over the shadow volumes. For almost 20 years, such methods have received little attention as they have been considered lacking of both robustness and efficiency. We show that these issues can be overcome, leading to a simple and robust shadow algorithm. Hence we demonstrate that this kind of approach can reach a high level of performance. Our algorithm uses a new partitioning strategy which avoids any polygon clipping. It relies on a Ternary Object Partitioning tree, a new data structure used to find if an image point is shadowed. Our method works on a triangle soup and its memory footprint is fixed. Our experiments show that it is efficient and robust, including for finely tessellated models.