Natural lighting and medieval glass - Scientific data acquisition, methodology and physically based rendering

Abstract

Fundamental optical properties of materials are described by intrinsic parameters that can be concentrated in only one notion: the components of the complex dielectric tensor. Such a notion is relevant in any cases and we shall give examples of applications in the cultural heritage field. Modern glasses characterization and ancient or medieval glasses studies are described in terms of the general methodology exposed. After a great success in application to metals and alloys last 15 years, the limits and advantages of the ellipsometric measurements are described. The interaction of light with materials defined by their intrinsic (fundamental optical properties) and extrinsic (mainly geometrical whatever the scale of observation) properties is the internal engine of the simulation software. The scientific methodology is then called OCRE, Optical Constants for Rendering Evaluation. The computed images inserted in the text are obtained with the free and open-source spectral software Virtuelium, developed at Ecole Centrale Paris. © 2012 Springer-Verlag Berlin Heidelberg.