Extraction of Optical Characteristics of Diffuse Particles for Modelling a Dispersed Medium

Abstract

Currently, virtual prototyping, i.e. preliminary modelling of processes on a computer has become ubiquitous. It is also applied to modern automobile paints in order to correctly reproduce the colour of the paint. The most practically important task is colour matching: calculation of the paint composition necessary to obtain a given colour. The complexity of modelling the propagation of light in paint is due to its complex structure and the wide variety of pigments, including diffuse ones. This problem can be solved by simulation of the light scattering by the dispersed pigment particles. To do this we need the optical properties of pigments, which are often unknown. In this paper, we propose several different methods for extraction of the pigment properties by measuring the light scattering of specially prepared samples. All methods are based on minimizing the difference between measured and calculated scattering values as a function of pigment properties. The methods differ in the types of paint samples that must be prepared and measured to obtain the pigment data. We describe the operation of the methods and test their robustness. As a result, one method has proven to be much more robust to the measurement errors. The colour of the real sample was also compared with the calculated colour of the paint, in the modelling of which the obtained properties of the pigments were used.