Layered Materials in Real-Time Rendering

Author

Oskar Elek
Faculty of Mathematics and Physics, Charles University, Prague / Czech Republic
URL: http://www.oskee.wz.cz/stranka/oskee.php
E-mail: oskee[-AT-]centrum.cz

Abstract

Today's games and other real-time 3D applications often use only basic empirical models for modelling the appearance of materials and rely on complex geometry and texturing to make them more visually appealing. In this paper we explore the possibilities of bringing more physically plausible models to real-time 3D graphics.

We do this by implementing the layered BRDF of Weidlich and Wilkie on GPU. This model utilizes the well-known Torrance-Sparrow and Oren-Nayar microfacet models. We show how to make this layered model useful for real-time rendering through various optimizations. Then we derive two specialized models based on this basic layered model. These two models attempt to simulate the appearance of metallic car paints and metallic patinas.

Keywords: surface reflectance models, appearance modelling, layered materials

Paper

Download the full text here (pdf).

Examples

Click on the images to enlarge them.

Examples of the general layered model. From left to right: Two tori with different top layer roughnss; A glossy object with blue coating; A torus with varying varnish thickness; A diffuse concrete ball with shiny blue coating.

Increasing the top layer thickness produces more intensive but darker colours. From left to right: Relative thickness 0, 0.5, 1.0, 2.5, 4.5 and 10.0.

Examples of the presented specialized model for metallic car paint rendering with sparkling effect.

Temporal development of the typical greenish patina on a copper object using our specialized model for patina rendering.