Reconsidering Light Transport - Acquisition and Display of Real-World Reflectance and Geometry

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Matthias Hullin
In this thesis, we cover three scenarios that violate common simplifying assumptions about the nature of light transport. We begin with the first ingredient to any 3D rendering: a geometry model. Most 3D scanners require the object-of-interest to show diffuse reflectance. The further a material deviatesfrom the Lambertian model, the more likely these setups are to produce corruptedresults. By placing a traditional laser scanning setup in a participating (in particular, fluorescent) medium, we have built a light sheet scanner that delivers robust results for a wide range of materials, including glass.Further investigating the phenomenon of fluorescence, we notice that, despite its ubiquity, it has received moderate attention in computer graphics. In particular, to date no datadriven reflectance models of fluorescent materials have been available. To describe the wavelength-shifting reflectance of fluorescent materials, we define the bispectral bidirectional reflectance and reradiation distribution function (BRRDF), for which we introduce an image-based measurement setup as well as an efficient acquisition scheme.Finally, we envision a computer display that shows materials instead of colours, and present a prototypical device that can exhibit anisotropic reflectance distributions similar to common models in computer graphics.3D scanning, gonioreflectrometry, goniofluorometry, fluorescence, reflectance and reradiation, BRDF display