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 "shading"

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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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    A Simple Diffuse Fluorescent BBRRDF Model
    (The Eurographics Association, 2018) Jung, Alisa; Hanika, Johannes; Marschner, Steve; Dachsbacher, Carsten; Reinhard Klein and Holly Rushmeier
    Fluorescence - the effect of a photon being absorbed at one wavelength and re-emitted at another - is present in many common materials such as clothes and paper. Yet there has been little research in rendering or modeling fluorescent surfaces. We discuss the design decisions leading to a simple model for a diffuse fluorescent BBRRDF (bispectral bidirectional reflection and reradiation distribution function). In contrast to reradiation matrix based models our model is continuous in wavelength space. It can be parameterized by artificially designed spectra as well as by many publicly available physical measurements. It combines fluorescence and non-fluorescent reflectance, as most real-world materials are not purely fluorescent but also reflect some light without changing its wavelength. With its simple parameterization the BBRRDF is intended as a starting point for any physically based spectral rendering system aiming to simulate fluorescence. To that end we show how to continuously sample both incident and exitant wavelengths from our BBRRDF which makes it suitable for bidirectional transport, and we discuss energy and photon conservation in the context of fluorescence.
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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.