DIFFUSE AND SPECULAR REFLECTANCE FROM ROUGH SURFACES

We present a reflection model for isotropic rough surfaces that have b oth specular and diffuse components. The surface is assumed to have a normal distribution of heights. Parameters of the model are the surfac e roughness given by the rms slope, the albedo, and the balance betwee n diffuse and specular reflection. The effect of roughness on diffuse reflection is taken into account, instead of our modeling this compone nt as a constant Lambertian term. The model includes geometrical effec ts such as masking and shadowing. The model is compared with experimen tal data obtained from goniophotometric measurements on samples of til es and bricks. The model fits well to samples with very different refl ection properties. Measurements of the sample profiles performed with a laser profilometer to determine the rms slope show that the assumed surface model is realistic. The model could therefore be used in machi ne vision and computer graphics to approximate reflection characterist ics of surfaces. It could also be used to predict the texture of surfa ces as a function of illumination and viewing angles. (C) 1998 Optical Society of America.