This paper describes a software package called 3D Distortion Model (3DDM), which we developed to provide a better understanding of stereoscopic display design. The software is based on contemporary geometric models of stereoscopic perception from the scientific literature. The user can input stereoscopic display design parameters, and the software will calculate the resultant image metrics and perceptual space distortions. There are several options for visualization of these results. In a live mode option, subsequent changes to design parameters will update calculations and imagery in real time. Additionally, the user can lock specific parameter values and explore how changes in one input variable will necessitate changes in another. Using both numerical output and provided figures, the user can predict how specific parameter changes and subsequent perceptual distortions may impact the usability of the display itself. This software provides the capability for considering scene information, display design and the human user experience.