Stereoscopic Volume Perception

Abstract

In the past five years, technological improvements have made it possible to capture, modify, and present technically good stereoscopic images. With devices able to capture high-resolution digital pictures and robust computer vision algorithms in post-production, today we are able to produce high-quality live-action stereoscopic content—from a technical point of view. This paper tackles an analytical question living in the art domain of stereoscopic cinema: When does a ball look flat like a frisbee disk, and when does it appear elongated like an egg? To analyze volume perception, we introduce a simple but powerful basic concept: A 1×1×1 m cube is used to virtually sweep through space away from the observer's eyes to infinity. For each distance, we measure the angles of width and depth on the observer's retina, which cause the retinal disparity that elicits stereopsis. This ratio leads to a width-to-depth sweep through space (width-to-depth ratio versus distance). The same test setup is then duplicated. Instead of the eyes two cameras are connected to a virtual cinema where an observer sits. Again a cube is swept through space and the width and depth angles are measured. Having established this basic concept, we then modify the parameters of focal length and interaxial distance and see how they affect the width-to-depth ratio. During evaluation, new dependencies are found between all parameters. Moreover, new measurement parameters are presented, which simplify the usage of depth volume in stereoscopic photography.