Depth Acuity Methodology for Electronic 3D Displays: eJames (eJ)

An electronic version (eJ) of the James (J) test of depth acuity is created and evaluated on three different types of 3D electronic displays: one active-eyewear Stereo 3D (S3D) and two non-eyewear full parallax Field-of-Light Display (FoLD) systems. The two FoLD systems are the Actuality Integral Slice (AIS) swept-screen volumetric Perspecta and the Zebra Integral Ray (ZIR) hogel-based ZScape Motion Display (ZMD). The James test is designed so that the only factor examined is binocular single vision (BSV), aka stereoscopic parallax. The James Depth Perception Apparatus (DPA) comprises two vertical white 1cm wide rods (or thin strings) viewed at a reference distance (e.g. 6m) against a black background through a window in a black front. The eJ computer graphics white bar stimuli in this work are designed to visually emulate -- within limitations of the S3D, AIS, and ZIR -- the white rods in the James DPA. The unique artifacts of the three electronic display types impede creation of a single graphical representation of the two-bar stimuli and complicate cross-type comparisons. A compact variant of the James DPA developed by Howard made the left rod stationary and right rod adjustable by the subject (rather than the administrator) via a hand-crank to match distance via a mechanical string-pulley system. The Howard DPA variant also enabled depth acuity threshold determination by two methods: (a) forced-choice of nearest bar; (b) adjustment of right bar to match left. An AFRL-automated Howard DPA is included in the present study to enable a comparison of real-world stimuli versus the electronic displays. A hand-held computer game controller is used to automate data collection and subject trial initiation. Four software interfaces are developed to control the stimuli positions presented on the three 3D electronic systems and the automated DPA; the right bar is randomly positioned from trial to trial.