Described is a user interface that displays a representation of a stereo scene, and includes interactive mechanisms for changing parameter values that determine the perceived appearance of that scene. The scene is modeled as if viewed from above, including a representation of a viewer's eyes, a representation of a viewing screen, and an indication simulating what each of the viewer eyes perceives on the viewing screen. Variable parameters may include a vergence parameter, a dolly parameter, a field-of-view parameter, an interocular parameter and a proscenium arch parameter.