VG10: Eurographics/IEEE VGTC on Volume Graphics

Permanent URI for this collection

https://diglib.eg.org/handle/10.2312/468

Browse

Browsing VG10: Eurographics/IEEE VGTC on Volume Graphics by Subject "Categories and Subject Descriptors (according to ACM CCS): I.3.3 [Computer Graphics]: Picture/Image Generation-Display algorithms"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Fast Volumetric Data Exploration with Importance-Based Accumulated Transparency Modulation
    (The Eurographics Association, 2010) Wan, Yong; Hansen, Chuck; Ruediger Westermann and Gordon Kindlmann
    Direct volume rendering techniques have been successfully applied to visualizing volumetric datasets across many application domains. Due to the sensitivity of transfer functions and the complexity of fine-tuning transfer functions, direct volume rendering is still not widely used in practice. For fast volumetric data exploration, we propose Importance-Based Accumulated Transparency Modulation which does not rely on transfer function manipulation. This novel rendering algorithm is a generalization and extension of the Maximum Intensity Difference Accumulation technique. By only modifying the accumulated transparency, the resulted volume renderings are essentially high dynamic range. We show that by using several common importance measures, different features of the volumetric datasets can be highlighted. The results can be easily extended to a high-dimensional importance difference space, by mixing the results from an arbitrary number of importance measures with weighting factors, which all control the final output with a monotonic behavior. With Importance-Based Accumulated Transparency Modulation, the end-user can explore a wide variety of volumetric datasets quickly without the burden of manually setting and adjusting a transfer function.
  • Thumbnail Image
    Item
    Feature-Driven Ambient Occlusion for Direct Volume Rendering
    (The Eurographics Association, 2010) Ancel, Alexandre; Dischler, Jean-Michel; Mongenet, Catherine; Ruediger Westermann and Gordon Kindlmann
    Ambient occlusion techniques were introduced to improve data comprehension by bringing soft fading shadows. They consist in attenuating light by considering the occlusion resulting from the presence of neighboring structures. Recently introduced in volume rendering, we show that the straightforward application of ambient occlusion in direct volume rendering has its limits as rendering a multi-layer volume results in overdarkening the internal layers of the volume. This paper proposes to address the overdarkening issue by computing ambient occlusion according to the features present in the dataset. This allows us to neglect inter-occlusions between features without losing the auto-occlusions that give cues on the shape of the considered features. We use a GPU-based approach with bricking to speed up the computations of our ambient occlusion method. Results show that our approach not only improves the visual quality of images compared to classical ambient occlusion, but it is also less parametersensitive, thus furthermore improving usability for every-day users.