In this paper we study the growth of surface roughness during sputtering of transparent SnO2 films onto rough glass substrates. Films in the thickness range 50–1200 nm were produced, and the optical characterization was made with a spectroscopic total integrating scattering instrument in the wavelength range 0.35≪λ≪1.0 μm. Optical constants for the different SnO2 films were determined. The observed spectral behavior of the diffuse reflectance (transmittance), as compared to the total reflectance (transmittance), could be explained by first-order vector perturbation theory in conjunction with a surface growth model incorporating both smoothing and roughening effects. Good agreement between calculated and measured reflectance and transmittance spectra was found, only by assuming partially correlated interface roughness. The scattering calculations rely on atomic force microscope measurements of the glass substrate and the front surfaces of the films, and a model of the cross correlation that describes the propagation of surface features through the new layer. The obtained replication factor gave additional information on the contribution of the substrate roughness to the film front surfaces. © 2000 American Institute of Physics.