The area of stereoscopic visualization is defined as the union of four different science areas: Visualization, Computer Graphics (i.e. stereoscopy), Psychology (i.e. depth perception), and Human Computer Interaction. The paper concentrates on the complex integration of various perceptual cues and rendering and interaction in stereoscopic environments. It discusses human factors of stereoscopic visualization systems and argues that they must be integral part of the design of visualization tools. Furthermore, it highlights the role of the user as a central part of the visualization process.