Stereography is the art and science of three-dimensional vision. 3-D imaging techniques are created by science and given expression through art. Artists have for centuries attempted to give their images the effects of volume and depth. The scientific use of perspective in art roughly parallels the rise of the printing press and the scientific revolution which has transformed the world. Through their use in the mass media of commercial photography, newsprint and film, 3-D images have become a significant part of American, and international, popular culture. Simultaneously, a wide range of 3-D imaging techniques have applications in medicine, industry and science as well as entertainment and the fine arts. Stereopsis, the perception of depth, is a result of the fact that our vision is binocular. Since our eyes are separated by a distance of about two and a half inches, we perceive any object from two separate viewpoints at the same time. 3-D imaging techniques involve the mechanical reconstruction of binary stereopsis. As early as 1584 Leonardo da Vinci, one of the great scientific artists, studied the perception of depth.