Computer Graphics and Human Depth Perception with Gaze-Contingent Depth of Field
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Virtual Reality (VR) -- the use of a computer to create a simulated environment that can be entered and interacted with as if it were real -- is finding important applications, especially in architectural design and in the medical community. Using a wheelchair incorporated into to a VR system, architects discovered a flaw in their design of a 140-room hospital; the bathroom countertops were two inches too far for wheelchair-bound patients to use the sinks . As a training tool in medical schools, VR allows students to practice surgery using an immersive interface, reducing the need for cadavers . These applications for virtual reality require an accurate perception of depth be presented to the user; one cannot afford to use a system that trains the user to systematically underestimate or overestimate distances in delicate operations. Unfortunately, for reasons unknown, an established compression effect -- where the virtual world is perceived to be significantly smaller than what it is intended to be -- is plaguing most virtual reality systems3. It is this dilemma that is motivating my research. I believe the problem is in the visual image of the VR system. Seeing a consistently, in-focus and detailed image on a computer screen sends cues to the human eye that the object displayed is flat. In the real world, objects behind and in front of an object of attention are seen as being blurred or out-of-focus, an effect known as depth of field. The depth of field effect occurs because of the eye lens accommodating for any given point in focus. Although eye lens accommodation cannot be safely or practically manipulated in the lab, the image that would have been created on a person s retina due to correct accommodation can be replicated. This visual image with blur from a finite depth of field has not been established as a depth cue, but there is evidence to suggest it aids in depth perception. I hypothesize that the visual image does play a role and that by adding the correct depth of field blur producing the image that would have appeared on the retina had accommodation been operating will improve the accuracy of depth perception on 3-D computer displays and help eliminate the compression factor currently affecting VR systems.