Junya Nakamura

Super multi-view display with a lower resolution flat-panel display

A lenticular-type super multi-view (SMV) display normally requires an ultra high-resolution flat-panel display. To reduce this resolution requirement, two or more views are generated around each eye with an interval smaller than the pupil diameter. Cylindrical lenses constituting a lenticular lens project a group of pixels of the flat-panel display to generate a group of viewing zones. Pixel groups generating left and right viewing zones through the same cylindrical lens are partitioned to separate the two zones. The left and right pixel groups for different cylindrical lenses are interlaced horizontally. A prototype SMV display is demonstrated.

Analysis of longitudinal viewing freedom of reduced-view super multi-view display and increased longitudinal viewing freedom using eye-tracking technique

— The viewing freedom of the reduced-view super multi-view (SMV) display was analyzed. It was found that there are separate multiple viewing ranges in the depth direction; thus, a technique that selects an appropriate viewing range to increase the longitudinal viewing freedom has been developed. Pixels of a flat-panel display viewed by the viewers eyes through a lenticular lens were determined from three-dimensional (3-D) positions of the viewers eyes, which were obtained using an eye-tracking system that employed a stereo camera. Parallax images corresponding to the 3-D positions of the viewers eyes were generated, which were displayed by the determined pixels. The experimental results show that the proposed technique successfully increased the longitudinal viewing freedom. It is also shown that a video camera was able to focus on the produced SMV images.

Generation of 360-degree color three-dimensional images using a small array of high-speed projectors to provide multiple vertical viewpoints

The generation of full-parallax and 360-degree three-dimensional (3D) images on a table screen is proposed. The proposed system comprises a small array of high-speed projectors and a rotating screen. Because the screen has a lens function, a large number of viewpoints are generated on a circle when the screen rotates. Thus, 360-degree 3D images having horizontal parallax are generated. Because all projectors are located at different heights from the screen, they generate the viewpoints on a circle at different heights. Therefore, plural viewpoints are aligned in the vertical direction to provide vertical parallax. A prototype display system that employs three high-speed color projectors is constructed.

Zone plate method for electronic holographic display using resolution redistribution technique

The resolution redistribution (RR) technique can increase the horizontal viewing-zone angle and screen size of electronic holographic display. The present study developed a zone plate method that would reduce hologram calculation time for the RR technique. This method enables calculation of an image displayed on a spatial light modulator by performing additions of the zone plates, while the previous calculation method required performing the Fourier transform twice. The derivation and modeling of the zone plate are shown. In addition, the look-up table approach was introduced for further reduction in computation time. Experimental verification using a holographic display module based on the RR technique is presented.

Development of a Holographic Display Module Using a 4k2k-SLM Based on the Resolution Redistribution Technique

A holographic display module with a viewing zone angle of 10.5° and a screen size of 2″ was developed using a 4k2k-SLM. This module has a frameless screen so that multiple modules can be arranged seamlessly.

Accommodation responses to horizontal-parallax-only super-multiview display

Super multi-view (SMV) displays have been developed to solve the vergence-accommodation conflict that causes visual fatigue with conventional three-dimensional (3D) displays. An ideal SMV display should generate dense viewpoints in both the horizontal and vertical directions. However, the SMV displays developed so far generate dense viewpoints only in the horizontal direction because of the system complexity required for full-parallax systems. Therefore, the accommodation responses to SMV displays were measured mostly for 3D images that contain distinctive vertical edges. In this study, we investigated the influences of the edge properties contained in 3D images upon the accommodation responses evoked by horizontal-parallax-only (HPO) SMV displays. We used the recently developed reduced-view SMV display, whose interval of viewpoints was 2.6 mm, for the accommodation measurements. Two test images were used: a “Maltese cross”, which contains several sharp edges, and a standard test image of “Lenna”, which contains various types of edges. We found that the HPO–SMV display still evoked the accommodation responses when “Lenna” was displayed. There were two types of accommodation responses for “Lenna”; the amounts of the evoked accommodation were smaller than or similar to those for the “Maltese cross”, depending on where the viewers gazed.

Vertical parallax added tabletop-type 360-degree three-dimensional display

The generation of full-parallax and 360-degree three-dimensional (3D) images on a tabletop screen is proposed. The proposed system comprises a small array of high-speed projectors and a rotating screen. All projectors are located at different heights from the screen. The lens shift technique is used to superimpose all images generated by the projectors onto the rotating screen. Because the rotating screen has an off-axis lens function, the image of the projection lens generates a viewpoint in the space, and the screen rotation generates a number of viewpoints on a circle around the rotating screen. Because all projectors are located at different heights, different projectors generate the viewpoints at different heights. Therefore, multiple viewpoints are aligned in the vertical direction to provide the vertical parallax. The proposed technique was experimentally verified. Three DMD projectors were used to generate three viewpoints in the vertical direction. The heights of the viewpoints were 720, 764, and 821 mm. Each projector generated 900 viewpoints on a circle. The diameter of the rotating screen was 300 mm. The frame rate was 24.7 Hz. The generation of 360-degree 3D images with the horizontal and vertical parallaxes was verified.

Enlargement of viewing freedom of reduced-view SMV display

In order to reduce the resolution of a flat-panel display used for the super multi-view (SMV) display, we previously proposed a reduced-view SMV display that generates views only around a viewers left and right eyes. A face-tracking system with one camera was combined with the reduced-view SMV display to enlarge the viewing freedom. However, the viewing freedom in the depth direction was limited. In the present study, we propose a SMV display system which generates views corresponding to three-dimensional (3D) positions of the viewers eyes to enlarge the viewing freedom in both the horizontal and depth directions. An eye-tracking system with a stereo camera is combined with the previously developed reduced-view SMV display. Pixels on the flat-panel display that are seen through each cylindrical lens are determined geometrically for all of the cylindrical lenses. Parallax images are generated corresponding to the 3D positions of the viewers eyes. To achieve the SMV display condition, two or more consecutive pixels including the determined pixels are used to display the parallax images. The enlargement of the viewing freedom was confirmed by the experiments.

Long-range 3D display using a collimated multi-layer display

We propose a long-range three-dimensional (3D) display using a collimated optics with multi-plane configuration. By using a spherical screen and a collimating lens, users observe the collimated image on the spherical screen, which simulates an image plane located at optical infinity. By combining and modulating overlapped multi-plane images, the observed image is located at desired depth position within the volume of multiple planes. The feasibility of the system is demonstrated by an experimental system composed of a planar and a spherical screen with a collimating lens. In addition, accommodation properties of the proposed system are demonstrated according to the depth modulation method.

Depth-fused Display for Expression of Objects with Large Depth Range

A depth-fused display covering a wide depth is proposed using collimated optics. An imaging plane is located at infinity by a spherical screen and a lens. The feasibility is demonstrated by an experimental system.