This study investigated perceptual and cognitive issues relating to manipulations in geometric field-of-view (GFOV) in perspective displays and the effects of incorporating virtual environment enhancements in the interface based on visual momentum (VM) techniques. Geometric field-of view determines the field-of-view (FOV) for perspective displays. Systematic errors in size and distance have been shown to occur in perspective displays as the result of changes in the GFOV. Furthermore, as humans' normal FOV becomes restricted, their ability to acquire spatial information is reduced resulting in a incomplete formulation and representation of the visual world. The magnitude of the resulting biases increase as task difficulty increases. It was predicted that as VM increases in the interface, the ability to overcome problems associated with restricted FOVs will also increase.

Sixty participants who were pre-tested for spatial ability were required to navigate through a virtual office building while estimating space dimensions and performing spatial orientation and representation tasks. A 3 x 2 x 2 mixed-subjects design compared three levels of GFOV, two levels of VM, and two levels of Difficulty.

The results support the hypothesis that 60° is the optimum GFOV for perspective displays. VM increased accuracy for space dimension estimates, reduced direction judgment errors, improved distance estimates when task difficulty was increased, improved participants' cognitive maps, and reduced the error for reconstructing the spatial layout of objects in a virtual space. The results also support the hypothesis that wider FOVs are needed to accurately perform spatial orientation and representation tasks in virtual environments. Spatial ability was also shown to influence performance on some of the tasks in this experiment.

This study effectively demonstrates that the spatial characteristics of architectural representations in perspective displays are not always accurately perceived. There is a clear tradeoff for setting GFOV in perspective displays: A 60° GFOV is necessary for perceiving the basic characteristics of space accurately; however, if spatial orientation and representation are important, a 90° FOV or larger is required. To balance this tradeoff if symbolic enhancements are included in the virtual environment, such as VM techniques, larger FOVs are less of a concern.