Microstructural and optical properties of obliquely deposited thin films are simulated in a computer 3D method. Identical hard sphere particles arrive serially as the simulation proceeds and relax into the nearest site where they touch the particle of impact and two others. Structural and optical properties are calculated from the resulting 3D array of particles. Peaks in the radial distribution function of simulated films are in agreement with particle to particle distances in small clusters and indicate that the films are amorphous. Columnar directions are identified by a maximum in the variance of the film density and results are given for several deposition geometries. Form birefringence is indicated by anisotropy in the 2D angular distribution function viewed down the columns, and values of the three principal refractive indices are computed by an iterative method.