Modelling colour changes of wood for architectural CAD simulations

It is a fact that the natural material wood changes its appearance during weathering. This study deals with the modelling of the discolouration process on wood colour during natural weathering and the simulation of ageing effects on wood surfaces in computer graphics. A measurement-based technique was used to create a realistic simulation for weathered material.The surface colour for larch and Norway spruce samples was determined according to the CIEL*a*b* system during a natural weathering test over one year. Accordingly, the collected data are smoothed using a local regression method. Based on this model the natural colour changes of wood can be implemented in CAD software and the ageing of the building can be simulated by means of renderings.At the end of the weathering test the colour impression faded and achieved a grey colour. It was recognized that the simulation of the weathering effects and the actual changes during natural weathering are comparable. The developed method can be a starting point for further investigations.

► We model the discolouration process on larch and Norway spruce samples.
► We examine the experimental data on the changes in wood colour with locally weighted regression methods.
► The simulation of the discolouration effects and the actual changes during the natural weathering are comparable.