Efficient representation for measured reflectance : modelisation and edition

Keywords :

• réflectance
• matériaux
• BRDF

Computer graphics is a valuable tool used from industrial applications to entertainment; it enables creation of images from virtual scenes. One of the aims of computer graphics is to generate photorealistic scenes; an important part of realism is relying on the accuracy of material models. Hence, the study of material models and reflectance is crucial.
Recently, measured materials gained popularity. This works well for uniform materials but spatially varying materials present multiple challenges in acquisition, storage, rendering and edition. This thesis presents methods for processing and editing measured materials.
We make three specific contributions:
•	We propose a technique for fast acquisition of anisotropic spatially varying bidirectional reflectance (SVBRDF) with a limited amount of light directions and a fixed point of view. While not suitable for high fidelity measurements, it gives a starting point to edit a real-world material while other techniques require lengthy measurement time and complex gantry setups.
•	Then, we propose a pipeline to fit measured materials (BTF) to analytical materials (BRDF). This technique drastically decreases the memory footprint of a measured material by approximating it with analytical BRDFs parametrised with 2D maps. It allows direct edition of those 2D maps and combination of different materials from various datasets.
•	Finally, we introduce a method to mix the reflectance properties of two materials. We can use the shininess of a material with the anisotropy of another while allowing edition of each contribution separately.

Directors:

• Mr Nicolas Holzschuch (directeur de recherche - INRIA )

Raporteurs:

• Mr Jean Michel Dischler (Professeur - Université de Strasbourg )
• Mr Reinard Klein (Professeur - Universität Bonn )

Examinators:

• Mr Xavier Granier (Professeur - Institut d'Optique Graduate School )
• Mr Alexander Wolkie (Professeur associé - Univerzita Karlova )
• Mme Stefanie Wuhrer (Chargé de recherche - INRIA )