43-Issue 4

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https://diglib.eg.org/handle/10.2312/3607013

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Browsing 43-Issue 4 by Subject "Computing methodologies → Rendering"

Now showing 1 - 4 of 4
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    Bridge Sampling for Connections via Multiple Scattering Events
    (The Eurographics Association and John Wiley & Sons Ltd., 2024) Schüßler, Vincent; Hanika, Johannes; Dachsbacher, Carsten; Garces, Elena; Haines, Eric
    Explicit sampling of and connecting to light sources is often essential for reducing variance in Monte Carlo rendering. In dense, forward-scattering participating media, its benefit declines, as significant transport happens over longer multiple-scattering paths around the straight connection to the light. Sampling these paths is challenging, as their contribution is shaped by the product of reciprocal squared distance terms and the phase functions. Previous work demonstrates that sampling several of these terms jointly is crucial. However, these methods are tied to low-order scattering or struggle with highly-peaked phase functions. We present a method for sampling a bridge: a subpath of arbitrary vertex count connecting two vertices. Its probability density is proportional to all phase functions at inner vertices and reciprocal squared distance terms. To achieve this, we importance sample the phase functions first, and subsequently all distances at once. For the latter, we sample an independent, preliminary distance for each edge of the bridge, and afterwards scale the bridge such that it matches the connection distance. The scale factor can be marginalized out analytically to obtain the probability density of the bridge. This approach leads to a simple algorithm and can construct bridges of any vertex count. For the case of one or two inserted vertices, we also show an alternative without scaling or marginalization. For practical path sampling, we present a method to sample the number of bridge vertices whose distribution depends on the connection distance, the phase function, and the collision coefficient. While our importance sampling treats media as homogeneous we demonstrate its effectiveness on heterogeneous media.
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    Learning to Rasterize Differentiably
    (The Eurographics Association and John Wiley & Sons Ltd., 2024) Wu, Chenghao; Mailee, Hamila; Montazeri, Zahra; Ritschel, Tobias; Garces, Elena; Haines, Eric
    Differentiable rasterization changes the standard formulation of primitive rasterization -by enabling gradient flow from a pixel to its underlying triangles- using distribution functions in different stages of rendering, creating a ''soft'' version of the original rasterizer. However, choosing the optimal softening function that ensures the best performance and convergence to a desired goal requires trial and error. Previous work has analyzed and compared several combinations of softening. In this work, we take it a step further and, instead of making a combinatorial choice of softening operations, parameterize the continuous space of common softening operations. We study meta-learning tunable softness functions over a set of inverse rendering tasks (2D and 3D shape, pose and occlusion) so it generalizes to new and unseen differentiable rendering tasks with optimal softness.
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    Patch Decomposition for Efficient Mesh Contours Extraction
    (The Eurographics Association and John Wiley & Sons Ltd., 2024) Tsiapkolis, Panagiotis; Bénard, Pierre; Garces, Elena; Haines, Eric
    Object-space occluding contours of triangular meshes (a.k.a. mesh contours) are at the core of many methods in computer graphics and computational geometry. A number of hierarchical data-structures have been proposed to accelerate their computation on the CPU, but they do not map well to the GPU for real-time applications, such as video games. We show that a simple, flat data-structure composed of patches bounded by a normal cone and a bounding sphere may reach this goal, provided it is constructed to maximize the probability for a patch to be culled over all viewpoints. We derive a heuristic metric to efficiently estimate this probability, and present a greedy, bottom-up algorithm that constructs patches by grouping mesh edges according to this metric. In addition, we propose an effective way of computing their bounding sphere. We demonstrate through extensive experiments that this data-structure achieves similar performance as the state-of-the-art on the CPU but is also perfectly adapted to the GPU, leading to up to ×5 speedups.
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    Stereo-consistent Screen Space Reflection
    (The Eurographics Association and John Wiley & Sons Ltd., 2024) Wu, XiaoLoong; Xu, Yanning; Wang, Lu; Garces, Elena; Haines, Eric
    Screen Space Reflection (SSR) can reliably achieve highly efficient reflective effects, significantly enhancing users' sense of realism in real-time applications. However, when directly applied to stereo rendering, popular SSR algorithms lead to inconsistencies due to the differing information between the left and right eyes. This inconsistency, invisible to human vision, results in visual discomfort. This paper analyzes and demonstrates how screen-space geometries, fade boundaries, and reflection samples introduce inconsistent cues. Considering the complementary nature of screen information, we introduce a stereo-aware SSR method to alleviate visual discomfort caused by screen space disparities. By contrasting our stereo-aware SSR with conventional SSR and ray-traced results, we showcase the effectiveness of our approach in mitigating the inconsistencies stemming from screen space differences while introducing affordable performance overhead for real-time rendering.