Reconstruction of Spectral Bidirectional Reflectance Distribution Function for Metallic Coatings Based on Additivity of Scattering Spectrum

The spectral bidirectional reflectance distribution function(BRDF) of metallic coatings is related to its composition. It is of great significance to reconstruct the BRDF data of metallic coatings with similar composition quickly and accurately, which can guide the modeling of BRDF and reduce the workforce and material cost of BRDF data acquisition for metallic coatings. In order to solve this problem, this paper innovatively proposes a method to reconstruct the BRDF data of metallic coatings with similar composition by using that of a few metallic coatings based on the additivity of the scattering spectrum. In this method, the BRDF of metallic coatings is regarded as the linear combination of the BRDF of each component, which can be obtained by solving the linear equations. Then, the weighted summation method is used to reconstruct the BRDF data of the metallic coatings with similar components by giving different weights to the BRDF of each component. In the experiment, we selected six different proportions of bright yellow color cards from Pantone metallic color as samples, and the BRDF values of each sample were measured at an incident angle of 45 and a hemispherical reflection space with the wavelength range of 380 760 nm by the comparative measurement method. Then two color cards were selected to obtain the BRDF data of the basic components, and the BRDF data of the other four color cards with similar components were reconstructed by giving different weights to the BRDF data of the basic components. The experimental results show that the BRDF data of the reconstructed four color cards agree with the measured BRDF data under the geometric conditions of 45 incident angle and hemispherical reflection space. The RMSE of prediction results of BRDF were all less than 0. 057% and the GFC were up to 99.998%. The experimental results show that the proposed method has the characteristics of high accuracy and simple calculation, and can be used for BRDF data reconstruction of metallic coatings.