Browsing by Author "Poulin, Pierre"

Now showing 1 - 4 of 4
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    Neural UpFlow: A Scene Flow Learning Approach to Increase the Apparent Resolution of Particle-Based Liquids
    (ACM, 2021) Roy, Bruno; Poulin, Pierre; Paquette, Eric; Narain, Rahul and Neff, Michael and Zordan, Victor
    We present a novel up-resing technique for generating high-resolution liquids based on scene flow estimation using deep neural networks. Our approach infers and synthesizes small- and large-scale details solely from a low-resolution particle-based liquid simulation. The proposed network leverages neighborhood contributions to encode inherent liquid properties throughout convolutions. We also propose a particle-based approach to interpolate between liquids generated from varying simulation discretizations using a state-of-the-art bidirectional optical flow solver method for fluids in addition with a novel key-event topological alignment constraint. In conjunction with the neighborhood contributions, our loss formulation allows the inference model throughout epochs to reward important differences in regard to significant gaps in simulation discretizations. Even when applied in an untested simulation setup, our approach is able to generate plausible high-resolution details. Using this interpolation approach and the predicted displacements, our approach combines the input liquid properties with the predicted motion to infer semi-Lagrangian advection. We furthermore showcase how the proposed interpolation approach can facilitate generating large simulation datasets with a subset of initial condition parameters.
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    Particle-based Liquid Control using Animation Templates
    (The Eurographics Association and John Wiley & Sons Ltd., 2020) Schoentgen, Arnaud; Poulin, Pierre; Darles, Emmanuelle; Meseure, Philippe; Bender, Jan and Popa, Tiberiu
    It is notoriously difficult for artists to control liquids while generating plausible animations. We introduce a new liquid control tool that allows users to load, transform, and apply precomputed liquid simulation templates in a scene in order to control a particle-based simulation. Each template instance generates control forces that drive the global simulated liquid to locally reproduce the templated liquid behavior. Our system is augmented with a variable proportion of temporary particles to help efficiently reproduce the templated liquid density, with fewer requirements on the surrounding environment. The resulting control strategy adds only a small computational overhead, leading to quick visual feedback for resolutions allowing interactive simulation. We demonstrate the robustness and ease of use of our method on various examples in 2D and 3D.
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    SREC‐RT: A Structure for Ray Tracing Rounded Edges and Corners
    (© 2021 Eurographics ‐ The European Association for Computer Graphics and John Wiley & Sons Ltd, 2021) Courtin, Simon; Ribardière, Mickael; Horna, Sebastien; Poulin, Pierre; Meneveaux, Daniel; Benes, Bedrich and Hauser, Helwig
    Man‐made objects commonly exhibit rounded edges and corners generated through their manufacturing processes. The variation of surface normals at these confined locations produces shading details that are visually essential to the realism of synthetic scenes. The more specular the surface, the finer and more prominent its highlights. However, most geometric modellers represent rounded edges and corners with dense polygonal meshes that are limited in terms of smoothness, while tremendously increasing scene complexity. This paper proposes a non‐invasive method (i.e. that does not modify the original geometry) for the modelling and rendering of smooth edges and corners from any input polygonal geometry defined with infinitely sharp edges. At the heart of our contribution is a geometric structure that automatically and accurately defines the geometry of edge and corner rounded areas, as well as the topological relationships at edges and vertices. This structure, called SREC‐RT, is integrated in a ray‐tracing‐based acceleration structure in order to determine the region of interest of each rounded edge and corner. It allows systematic rounding of all edges and vertices without increasing the 3D scene geometric complexity. While the underlying rounded geometry can be of any type, we propose a practical ray‐edge and ray‐corner intersection based on parametric surfaces. We analyse comparisons generated with existing methods. Our results present the advantages of our method, including extreme close‐up views of surfaces with a much higher quality for very little additional memory, and reasonable computation time overhead.
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    Voxel-based Representations for Improved Filtered Appearance
    (The Eurographics Association, 2023) Brito, Caio José Dos Santos; Poulin, Pierre; Teichrieb, Veronica; Bikker, Jacco; Gribble, Christiaan
    Volumetric representations allow filtering of mesh-based complex 3D scenes to control both the efficiency and quality of rendering. Unfortunately, directional variations in the visual appearance of a volume still hinder its adoption by the real-time rendering community. To alleviate this problem, we propose two simple structures: (1) a virtual mesh to encode the directional distribution of colors and normals, and (2) a low-resolution subgrid of opacities to encode directional visibility. We precompute these structures from a mesh-based scene into a regular voxelization. During display, we use simple rendering methods on the two structures to compute the image contribution of the appearance of a visible voxel, optimizing for efficiency and/or quality. The improved visual results compared to previous work are a step forward to the integration of volumetric representations in real-time rendering.