1 Fred Books (1992) Final Technical Report to the National Science Foundation on University of North Carolina's Walkthough Project stated the following when reporting on stereopsis: "Stereo noticeably adds to the illusion of presence, but it makes much less difference in architectural modeling than in most applications. Architectural models have lots of parallel lines and planes, known to be perpendicular... Obscuration, perspective and the kinetic depth effect provide so strong a set of cues that stereo is almost frosting."