Creating a comfortable stereoscopic viewing experience: effects of viewing distance and field of view on fusional range

In stereoscopic display systems, there is always a balance between creating a “wow factor,” using large horizontal disparities, and providing a comfortable viewing environment for the user. In this paper, we explore the range of horizontal disparities, which can be fused by a human observer, as a function of the viewing distance and the field of view of the display. Two studies were conducted to evaluate the performance of human observers in a stereoscopic viewing environment. The viewing distance was varied in the first study using a CRT with shutter glasses. The second study employed a large field-of-view display with infinity focus, and the simulated field of view was varied. The recorded responses included fusion/no fusion, fusion time, and degree of convergence. The results show that viewing distance has a small impact on the angular fusional range. In contrast, the field of view has a much stronger impact on the angular fusional range. A link between the degree of convergence and the fusional range is demonstrated. This link suggests that the capability of the human observer to perform eye vergence movements to achieve stereoscopic fusion may be the limiting factor in fusing large horizontal disparities presented in stereoscopic displays.