NHK Science & Technical Research Laboratories develops light field head-mounted display for comfortable VR viewing –PRONEWS: Digital video production Web magazine

NHK Broadcasting Technology Research Institute (Giken) can watch natural 3D images by utilizing light field technology that reproduces reflected light from objects in the same way as in the real world, and can be expected to reduce eye strain. We have developed a head-mounted display (HMD).

Lightfield HMD configuration

NHK Science & Technical Research Laboratories is conducting research on VR (Virtual Reality) viewing devices such as HMDs as one of the future media technologies. With a conventional HMD, a three-dimensional effect can be obtained by projecting images with parallax between the left and right eyes, but since the focal position of the eyes is aligned with the display, it is thought that unnatural perception will occur and visual fatigue will occur. Has been done.

In the light field HMD developed this time, a lens array with many small lenses arranged is placed in front of the display, and the image (element image) of a small subject corresponding to each lens is displayed on the display.

A group of element images in which small element images are arranged is generated in real time according to the movement of the HMD and displayed on the display.This image and lens array reproduce the rays of a 3D scene as in the real world.

With this method, the focal position of the eyes is unconsciously adjusted according to the position in the depth direction of the subject, as in the real world, and it is expected to suppress visual fatigue because natural 3D viewing is possible. ..

Since I am looking at the subject in the foreground, I can see clearly in the foreground and blurry in the distance (left). Since I am looking at the subject in the back, I can see the back clearly and the front looks blurry (right).
* Although it looks natural in the real world, with the conventional HMD, the focal position of the eyes is fixed regardless of the position in the depth direction you are trying to see, and the appearance such as blurring does not change.

In addition, with the Lightfield HMD, the 3D image generated between the lens array and the eyepiece can be magnified and viewed with the eyepiece, but the problem was that the depth dimension became large. This time, by forming this 3D image as a virtual image on the outside of the display, the distance between the lens array and the eyepiece could be reduced, and the size of a general HMD could be achieved.

Lightfield HMD optical system design

In the future, the company aims to improve the optical system such as the lens array to improve the quality of 3D images, verify the display characteristics through evaluation experiments, and realize a device that enables more comfortable VR viewing.