Study on Comparison Experiment of the Bidirectional Reflectance Distribution Function (BRDF) of the Surface of Exterior Decorative Materials for Buildings Under Dry and Wet Condition

Abstract

As Bidirectional Reflectance Distribution Function (BRDF) can describe the reflection and scattering characteristic of solid material surface better, an experiment which is based on the basic concept of BRDF and combined with the effects on surface profile from surface wettability theory and wet condition, was carried out for comparison. Using the white standard plate as a single sample for reference on a self-built experiment table, the BRDF values of the surface of three exterior decorative materials for buildings, namely granite, coated glass and Ethylene-Propylene-Diene-Monomer (EPDM), were measured under the conditions of dry and wet, on two wavebands (visible light band 0.6328μm and near infrared band 1.34μm) and at different incident angles. After the comparison of distribution, the results indicate that if forming stable water-film, which has the function of translucent smooth interface, above the surface of the three materials, their BRDF values will demonstrate obvious specular reflection component to different degree.