Light‐field head‐mounted displays reduce the visual effort: A user study

Abstract

Head‐mounted displays (HMDs) allow the visualization of virtual content and the change of view perspectives in a virtual reality (VR). Besides entertainment purposes, such displays also find application in augmented reality, VR training, or tele‐robotic systems. The quality of visual feedback plays a key role for the interaction performance in such setups. In the last years, high‐end computers and displays led to the reduction of simulator sickness regarding nausea symptoms, while new visualization technologies are required to further reduce oculomotor and disorientation symptoms. The so‐called vergence–accommodation conflict (VAC) in standard stereoscopic displays prevents intense use of 3D displays, so far. The VAC describes the visual mismatch between the projected stereoscopic 3D image and the optical distance to the HMD screen. This conflict can be solved by using displays with correct focal distance. The light‐field HMD of this study provides a close‐to‐continuous depth and high image resolution enabling a highly natural visualization. This paper presents the first user‐study on the visual comfort of light‐field displays with a close‐to‐market HMD based on complex interaction tasks. The results provide first evidence that the light‐field technology brings clear benefits to the user in terms of physical use comfort, workload, and depth matching performance.

Toward physically realistic vision in teleoperation: A user study with light‐field head mounted display and 6‐DoF head motion

“…Obviously, the subjects tried to use the additional information of the light-field display (potentially increased confidence) and to correct the position accordingly, even if they could not achieve a more accurate result compared to the condition without light-field. Contrary to the prior study 9 (where the depth map was perfect and 3D instead of 2.5D), no evidence was found that light-field technology directly reduces the visual strain of the human operator and no effects in the SSQ and VSQ queries were found. Yet, the overall workload ratings indicated lower values when light-field was available compared to the condition without.…”

“…In literature, for instance, holographic displays 11 and such based on microlens arrays, multiple depth planes, 12,13 or varifocal elements (e.g., focus‐tunable lenses 14,15 or deformable membrane mirrors 16 ) were proposed to display different depth areas. The light‐field head‐mounted display of this work (Creal Zorya 17 ) was already applied in Panzirsch et al 9 . This work confirmed for the first time that light‐field HMDs can reduce the visual effort for the user in VR applications with perfect visual information.…”

“…The HMD allows the adjustment of the inter‐pupillary distance (IPD), that is, the individual distance between the two eyes, between 58 and 72 mm. The reader is referred to Panzirsch et al 9 . for detailed information on the display technology.…”

“…Comparing the results from the experimental blocks with (LF on) versus without light-field (LF off ) showed no significant effects on the positional accuracy, which is also in line with prior experiments of the authors. 9 However, path lengths were significantly longer when positioning the most distant peg (Peg 1) with light-field activated. This effect can best be explained by the fact that the depth of field resolution decreases the further away an object is.…”

“…In most telerobotic setups, the remote environment is visualized to the human operator via head-mounted displays since they enable intuitive stereo vision at large head motions. Still, recent studies in VR environments 8,9 indicate that operating with conventional head-mounted displays (HMD, with fixed focus) cause high visual effort or even eye strain for the operator, thus heavily limiting the application period in VR as well as telerobotics due to reduced usability. One of the main reasons for increased visual effort is the so-called vergence-accommodation conflict (VAC) resulting from non-matching 3D and focusing distance.…”