Browsing by Author "Benamira, Alexis"

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    A Combined Scattering and Diffraction Model for Elliptical Hair Rendering
    (The Eurographics Association and John Wiley & Sons Ltd., 2021) Benamira, Alexis; Pattanaik, Sumanta; Bousseau, Adrien and McGuire, Morgan
    Realistic hair rendering relies on fiber scattering models. These models are based on either ray tracing or on full wavepropagation through the hair fiber. Ray tracing can model most of the scattering phenomenon observed but misses the important effect of diffraction. Indeed human natural hair specific dimensions and geometry demands for the wave nature of light to be taken into consideration for accurate rendering. However, current full-wave model requires nonpratical, several days precomputation, that needs to be repeated for every change in the hair geometry or color, for appropriate results. We present in this paper a dual hair scattering model which considers the dual aspect of light: as a wave and as a ray. Our model accurately simulates both diffraction and scattering phenomena without requiring any precomputation. Furthermore, it can simulate light transport in hairs of arbitrary elliptical cross-sections. This new dual approach enables our model to significantly improve the appearance of rendered hair and qualitatively match scattering and diffraction effects seen in photos of real hair while adding little computation overhead.
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    A Microfacet Model for Specular Fluorescent Surfaces and Fluorescent Volume Rendering using Quantum Dots
    (The Eurographics Association, 2023) Benamira, Alexis; Pattanaik, Sumant; Ritschel, Tobias; Weidlich, Andrea
    Fluorescent appearance of materials results from a complex light-material interaction phenomenon. The modeling of fluorescent material for rendering has only been addressed through measurement or for simple diffuse reflections, thus limiting the range of possible representable appearances. In this work, we introduce and model a fluorescent nanoparticle called a Quantum Dot (QD) for rendering. Our modeling of the Quantum Dots serves as a foundation to support two physically based rendering applications. First a fluorescent volumetric scattering model and second, the definition of a fluorescent specular microfacet scattering model. For the latter, we model the Fresnel energy reflection coefficient of a QD coated microfacet assuming specular fluorescence, thus making our approach easily integrable with any microfacet reflection model.