MAM2018: Eurographics Workshop on Material Appearance Modeling

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https://diglib.eg.org/handle/10.2312/2632655

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Browsing MAM2018: Eurographics Workshop on Material Appearance Modeling by Subject "I.3.7 [Computer Graphics]"

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    Iso Photographic Rendering
    (The Eurographics Association, 2018) Porral, Philippe; Lucas, Laurent; Muller, Thomas; Randrianandrasana, Joël; Reinhard Klein and Holly Rushmeier
    In the field of computer graphics, the simulation of the visual appearance of materials requires an accurate computation of the light transport equation. Consequently, material models need to take into account various factors which may influence the spectral radiance perceived by the human eye. Though numerous relevant studies on the reflectance properties of materials have been conducted to date, environment maps used to simulate visual behaviors remain chiefly trichromatic. Whereas questions regarding the accurate characterization of natural lighting have been raised for some time, there are still no real sky environment maps that include both spectral radiance and polarization data. Under these conditions the simulations carried out are approximate and therefore insufficient for the industrial world where investment-sensitive decisions are often made based on these very calculations.
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    On the Advancement of BTF Measurement on Site
    (The Eurographics Association, 2018) Havran, Vlastimil; Hosek, Jan; Nemcova, Sarka; Cap, Jiri; Reinhard Klein and Holly Rushmeier
    We present our progress to the on-site measurement of the spatially varying surface reflectance represented by bidirectional texture function (BTF). This requires a physical realization of a portable instrument that can be brought to the sample, outside the laboratory. We discuss our motivation, the main issues, and challenges for making such an instrument possible. We focus on the design of the mechanical parts that are required for an easy manipulation of the device on site and describe our experiences with the instrument in practice. The design uses a miniaturized rotary light stage. It allows for measurement of HDR images with the acquisition rate of 1000 HDR images per minute, where one HDR image consists of 4 individual exposures.
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    Towards a Principled Kernel Prediction for Spatially Varying BSSRDFs
    (The Eurographics Association, 2018) Elek, Oskar; Krivánek, Jaroslav; Reinhard Klein and Holly Rushmeier
    While the modeling of sub-surface translucency using homogeneous BSSRDFs is an established industry standard, applying the same approach to heterogeneous materials is predominantly heuristical. We propose a more principled methodology for obtaining and evaluating a spatially varying BSSRDF, on the basis of the volumetric sub-surface structure of the simulated material. The key ideas enabling this are a simulation-data driven kernel for aggregating the spatially varying material parameters, and a structure-preserving decomposition of the sub-surface transport into a local and a global component. Our current results show significantly improved accuracy for planar materials with spatially varying scattering albedo, with added discussion about extending the approach for general geometries and full heterogeneity of the material parameters.
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    Towards Physically Based Material Appearance in the Thermal Infrared Spectrum: A Short Survey
    (The Eurographics Association, 2018) Haraké, Laura; Burkard, Eva; Reinhard Klein and Holly Rushmeier
    In the context of photorealistic rendering, global illumination mainly relies on material models from the visible spectrum, whereas thermal infrared signatures receive only little attention. This paper outlines physical principles for determining the temperature distributions within a 3D scene and with it the overall radiance reaching an IR sensor. Hitherto existing approaches for physically based rendering are surveyed. Supposing that those methods still can benefit from recent rendering concepts in visible spectrum, we point out possible transfers.