DSC'99 - Driving Simulation Conference July 7-8, 1999 - PARIS

Interactive Headlight Simulation

P. Lecocq, J-M. Kelada, A. Kemeny
Renault Direction de la Recherche - Research Department
Technocentre Renault TCR AVA 2 12
1, av du Golf 78288 Guyancourt Cedex &emdash; France
Tel: +33 1 76 85 19 85 Fax : +33 1 76 85 27 30 e-mail : andras.kemeny@renault.fr


Headlight simulation has been recently studied for the conception of a new car projector by automotive car makers and suppliers. It allows the study of a supplier's numerical solution without making a physical prototype. Unfortunately, most simulations are difficult to be implemented in real-time, computed by raytracing algorithms [1] or radiosity technics [2], and are often visualised on a small screen. Consequently, the operator cannot test his simulated projector in driving conditions. In order to have an interactive simulation, computer generated images need to be rendered in real-time. The real-time constraint implies the use of graphic hardware engine and optimised lighting models. However the choice of the lighting model is critical because of the necessity of high level image quality in rendering the light distribution of the projector.

Renault, Direction de la Recherche, has recently developed such interactive headlight simulation software. Several parameters can be set in real-time, such as the position and the orientation of the headlamp. It is also possible to take photometric measures on the road during the simulation.

The light distribution of the projector is taking into account according to its photometric description. More precisely, a projector is assimilated as a positional light source which deliver correct attenuation. The photometric description (in Lux) of the projector is encoded in a texture [3] which modulate the effect of the light source on a polygonal surface. Thus, the precision of the simulation directly depend on the level of precision of the photometric description and the level of detail of the scene in term of polygons.

The headlight simulation software was integrated in Renault's driving simulators in 1998 and validated by inhouse photometric laboratory and supplier measurements. New investigations are now studied for extend the headlight simulation to different weather conditions.

References :

[1] A. Glassner. Principles of Digital Image Synthesis, Vol 1 and 2, Morgan Kaufman Publishers, Inc, 1995.

[2] Michael F. Cohen and John R. Wallace. Radiosity and Realisitic Image Synthesis. Academic Press Professional, Inc., first edition, 1993.

[3] M. Segal, C. Korobkin, R. van Widenfelt, J. Foran, P. Haeberli. Fast Shadows and Lighting Effects Using Texture Mapping. In Proceedings of SIGGRAPH 92, pages 249-252, 1992