Generalized Image Acquisition and Analysis

Acquisition and Analysis of Bispectral Bidirectional Reflectance and Reradiation Distribution Functions

In fluorescent materials, light from a certain band of incident wavelengths is reradiated at longer wavelengths, i.e., with a reduced per-photon energy. While fluorescent materials are common in everyday life, they have received little attention in computer graphics. Especially, no bidirectional reradiation measurements of fluorescent materials have been available so far. In this paper, we extend the well-known concept of the bidirectional reflectance distribution function (BRDF) to account for energy transfer between wavelengths, resulting in a Bispectral Bidirectional Reflectance and Reradiation Distribution Function (bispectral BRRDF). Using a bidirectional and bispectral measurement setup, we acquire reflectance and reradiation data of a variety of fluorescent materials, including vehicle paints, paper and fabric, and compare their renderings with RGB, RGB×RGB, and spectral BRDFs. Our acquisition is guided by a principal component analysis on complete bispectral data taken under a sparse set of angles. We show that in order to faithfully reproduce the full bispectral information for all other angles, only a very small number of wavelength pairs needs to be measured at a high angular resolution.


Measuring BRDFs of Immersed Materials

Kai Berger, Ilya Reshetouski, Marcus Magnor, Ivo Ihrke
In: Proceedings of VMV 2011.


We investigate the effect of immersing real-world materials into media of different refractive indices. We show, that only some materials follow the Fresnel-governed behaviour. In reality, many materials exhibit unexpected effects such as stronger localized highlights or a significant increase in the glossy reflection due to microgeometry. In this paper, we propose a new measurement technique that allows for measuring the BRDFs of materials that are immersed into different media.


author = {Kai Berger and Ilya Reshetouski and Marcus A. Magnor and Ivo Ihrke},
title = "{Measuring BRDFs of Immersed Materials}",
booktitle = {Proceedings of VMV},
pages = "325--330",
year = {2011},
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