Všechny publikace

QuadStack: An Efficient Representation and Direct Rendering of Layered Datasets

  • DOI: 10.1109/TVCG.2020.2981565
  • Odkaz: https://doi.org/10.1109/TVCG.2020.2981565
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    We introduce QuadStack, a novel algorithm for volumetric data compression and direct rendering. Our algorithm exploits the data redundancy often found in layered datasets that are common in science and engineering fields such as geology, biology, mechanical engineering, medicine, etc. QuadStack first compresses the volumetric data into vertical stacks that are then compressed into a quadtree that identifies and represents the layered structures at the internal nodes. The associated data (color, material, density, etc.) and shape of these layer structures are decoupled and encoded independently, leading to high compression rates (4× to 45×) of the original voxel model memory footprint in our experiments). We also introduce an algorithm for value retrieving from the QuadStack representation and we show that the access has logarithmic complexity. Because of the fast access, QuadStack is suitable for efficient data representation and direct rendering and we show that our GPU implementation performs comparable in speed with the state-of-the-art algorithms (18-79 MRays/s in our implementation), while maintaining a significantly smaller memory footprint

Spatio-temporal BRDF: Modeling and synthesis

  • DOI: 10.1016/j.cag.2021.04.001
  • Odkaz: https://doi.org/10.1016/j.cag.2021.04.001
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    We propose a generalization of example-based texture synthesis to spatio-temporal BRDFs. A key com-ponent of our method is a novel representation of time-varying materials using polynomials describing time-varying BRDF parameters. Our representation allows efficient fitting of measured data into a com-pact spatio-temporal BRDF representation, and it allows an efficient analytical evaluation of distances be-tween spatio-temporal BRDF parameters. We show that even polynomials of low degree are sufficient to represent various time-varying phenomena and provide more accurate results than the previously proposed representation. We are the first who applied the example-based texture synthesis on abstract structures such as polynomial functions. We present two applications of synthesizing spatio-temporal BRDFs using our method: material enlargement and transfer of time-varying phenomenon from an ex-ample to a given static material. We evaluated the synthesized BRDFs in the context of realistic rendering and real-time rendering.

Ray Classification for Accelerated BVH Traversal

  • DOI: 10.1111/cgf.13769
  • Odkaz: https://doi.org/10.1111/cgf.13769
  • Pracoviště: Katedra počítačové grafiky a interakce
  • Anotace:
    For ray tracing based methods, traversing a hierarchical acceleration data structure takes up a substantial portion of the total rendering time. We propose an additional data structure which cuts off large parts of the hierarchical traversal. We use the idea of ray classification combined with the hierarchical scene representation provided by a bounding volume hierarchy. We precompute short arrays of indices to subtrees inside the hierarchy and use them to initiate the traversal for a given ray class. This arrangement is compact enough to be cache-friendly, preventing the method from negating its traversal gains by excessive memory traffic. The method is easy to use with existing renderers which we demonstrate by integrating it to the PBRT renderer. The proposed technique reduces the number of traversal steps by 42% on average, saving around 15% of time of finding ray-scene intersection on average.

Za stránku zodpovídá: Ing. Mgr. Radovan Suk