Multiview 3D Display Research Articles

Ultrathin metasurface for super multi-view 3D display with linear and circular polarization control

Multiview 3D display technologies are advantageous due to their smooth motion parallax, visual discomfort alleviation, and wide depth of focus. However, the potential applications of this technology are constrained by its bulky size and limited light modulation capability. Metasurfaces offer diverse wavefront control by manipulating the phase, amplitude, and polarization of light. They provide design freedom and high image quality for multiview 3D display technologies. Here, we propose an ultrathin metasurface-based super multiview 3D display that can effectively modulate the flexibility of linearly polarized (LP) and circularly polarized (CP) electromagnetic waves. Numerical results demonstrate that it can produce 24 views together for LP and CP waves and high-quality reconstructed 3D images are obtained. The suggested metasurface for super multiview 3D display is promising to underpin the advancement of meta-optics-based operations in 3D display, imaging and integrated optics.

Edge highlighting with depth-dependent opacity gradation of laser-scanned point clouds improves the accuracy of perceived depth in transparent multi-view 3D visualizations

There is an activity called "digital archiving" in which cultural property is digitized for preservation and utilization, and transparent visualization using 3D point clouds is a valuable tool for understanding the complex internal structure of cultural property. However, when 3D data is transparently visualized, depth information may become unclear. In this paper, we investigated whether the depth perception of transparently visualized 3D objects can be improved by highlighting the 3D edges of the structures and adjusting the opacity of the edges according to the depth. In order to verify the effect of the depth-dependent 3D edges, we conducted a psychophysical experiment in which subjects were asked to report the magnitude of perceived depth for 3D structures of two cultural properties using a multi-view 3D display. The perceived depth was smaller than the simulated depth under all conditions. However, the opacity adjustment in edge highlighting mitigated the depth underestimation from an average of 69.4 to 35.5%. These results indicate that edge highlighting with opacity adjusted according to depth improves the accuracy of the perceived depth of 3D structures of cultural property visualized transparently.Graphical abstract

Ultrathin ring-shaped metasurface for a multiview 3D display

The development of glasses-free 3D multiview displays has opened up new avenues for experiencing 3D displays. Multiview technologies have the advantages of visual discomfort alleviation, smooth motion parallax, full-color display, and broad depth of focus. However, their intended uses are impeded due to the versatility of designing ultrathin display systems freely by using metasurface technology. This paper presents a technique for creating an ultrathin ring-shaped metasurface for a multiview display system with a thickness of 2 µm. The proposed multiview 3D display system generates eight views. Numerical simulations are used to confirm the efficacy of the suggested strategy, and the results demonstrate the attainment of a high-quality multiview 3D display. The proposed work demonstrates the potential applications of the metasurface in multiview display systems for electromagnetic wave manipulation in future 3D TVs, imaging, integrated optics, and next-generation compact displays.

P‐127: Pixel Aliasing Methods for Voxel Resolution Enhancement of Multiview Display

Pixel aliasing method is proposed to increase the resolution of multiview 3D display. where the deterioration of 3D image resolution occurs due to producing multiple directional images with limited display resolution. To overcome the resolution limitations of discrete voxels, we rearrange the image pixels by using the resizing technique and the interpolation method to enhance the 3D image resolution. We demonstrate the image resolution increase in both the depth and horizontal directions.

Design of Ultrathin Metasurface for Multiview 3D Display Based on Look-Up-Table Method

Design of Ultrathin Metasurface for Multiview 3D Display Based on Look-Up-Table Method

Chromatic correction for super multi-view 3D display based on diffraction theory.

The traditional analysis method for super multi-view 3D display based on geometric optics, which approximates the lenticular lenses as a series of pinhole structures, ignored the chromatic aberration. In this paper, the optimization method based on diffraction theory is proposed for super multi-view 3D display, where the wavefronts are evaluated accurately by the forward propagation method, and the chromatic aberration of the synthetic viewpoint image is reduced dramatically by the backward reconstruction optimization method (BROM). The optical experiment is performed to verify the feasibility of the method, which is consistent with numerical simulation results. It is proved that the proposed method simulates the physical propagation process of super multi-view 3D display and improves the reconstructed image quality. In the future, it can be used to achieve the super multi-view 3D light field technology with low crosstalk.

Voxel characteristic estimation of integral imaging display system using self-interference incoherent digital holography.

Three-dimensional (3D) images reconstructed by integral imaging display are captured as a complex hologram using self-interference incoherent digital holography (SIDH) and analyzed for the volumetric image characteristics. The integrated images can present 3D perception through not only binocular disparity but also volumetric property, which is represented in forming a volume picture element, called 'voxel', and an important criterion to distinguish the integral imaging from the multiview 3D display. Since SIDH can record the complex hologram under incoherent lighting conditions, the SIDH camera system has the advantage to measure the voxel formed with the incoherent light fields. In this paper, we propose a technique to estimate and analyze the voxel characteristics of the integral imaging system such as the depth location and resolution. The captured holograms of the integrated images are numerically reconstructed by depth for the voxel analysis. The depth location of the integrated image can be calculated and obtained using the autofocus algorithms and the focus metrics values, which also show the modalities of depth resolution. The estimation method of this paper can be applied to the accurate and quantitative analysis of the volumetric characteristics of light field 3D displays.

Motion parallax and lossless resolution autostereoscopic 3D display based on a binocular viewpoint tracking liquid crystal dynamic grating adaptive screen.

The autostereoscopic 3D display has two important indicators, both the number of viewpoints and display resolution. However, it's a challenge to improve both the viewpoint and the resolution. Here, we develop a fixed-position multiview and lossless resolution autostereoscopic 3D display system that includes the dynamic liquid crystal (LC) grating screen. This display system consists of an LC display panel and an LC grating screen. The synchronization of the frame switching of the LC display panel and the LC grating screen shutter enables the preserved resolution. The "eye space" design makes the viewpoint dense enough and determines the LC grating screen's parameters. We use binocular viewpoint tracking technology to realize the LC grating screen's adaptive control based on the above work. Different binocular views are rendered in real-time according to the different positions of a single pair of stereoscopic viewpoints in the eye space, making the motion parallax possible. We present the working principle and mathematical analysis. We implement a prototype for verifying the principle. According to the experiment results analysis, this prototype can achieve viewpoint tracking and motion parallax based on resolution lossless and viewpoint dense enough.

Conditions of a Multi-View 3D Display for Accurate Reproduction of Perceived Glossiness.

Visualizing objects as they are perceived in the real world is often critical in our daily experiences. We previously focused on objects' surface glossiness visualized with a 3D display and found that a multi-view 3D display reproduces perceived glossiness more accurately than a 2D display. This improvement of glossiness reproduction can be explained by the fact that a glossy surface visualized by a multi-view 3D display appropriately provides luminance differences between the two eyes and luminance changes accompanying the viewer's lateral head motion. In the present study, to determine the requirements of a multi-view 3D display for the accurate reproduction of perceived glossiness, we developed a simulator of a multi-view 3D display to independently and simultaneously manipulate the viewpoint interval and the magnitude of the optical inter-view crosstalk. Using the simulator, we conducted a psychophysical experiment and found that glossiness reproduction is most accurate when the viewpoint interval is small and there is just a small (but not too small) amount of crosstalk. We proposed a simple yet perceptually valid model that quantitatively predicts the reproduction accuracy of perceived glossiness.

Micro-projection dynamic backlight for multi-view 3D display

A micro-projection dynamic backlight for multi-view three-dimensional (3D) display is proposed. The proposed backlight includes a light emitting diodes (LEDs) array, a lenticular lens array, and a scattering film. The LED array, the lenticular lens, and the scattering film construct a micro-projection structure. In this structure, the LEDs in the array are divided into several groups. The light from each LED group can be projected to the scattering film by the lenticular lens and forms a series of bright stripes. The different LED groups have different horizontal positions, so these bright stripes corresponding to different LED groups also have different horizontal positions. Therefore, they can be used as a dynamic backlight. Because the distance between the LEDs array and the lenticular lens is much larger than the distance between the lenticular lens and the scattering films, the imaging progress will make the width of the bright stripes much smaller than that of the LEDs, and the pitch of the stripes is also decreased. According to the 3D display theory, the bright stripes with small width and pitch help to increase the number of views. Therefore, the proposed micro-projection dynamic backlight is very suitable for multi-view 3D display. An experimental prototype was developed, and the experimental results show that the micro-projection dynamic backlight can correctly complete the directional projection of the parallax images to form a 3D display.

Pixelated Blazed Gratings for High Brightness Multiview Holographic 3D Display

Multiview 3D display can reveal wondrous information of a 3D image without any visual aids. Therefore, it has great potential in many applications, such as education, game, training, and design. Among all the multiview 3D display techniques, the one that is based on diffractive optics and metasurface can present 3D images with ultrawide field of view and low crosstalk. However, the brightness of diffractive multiview 3D display is limited by the diffraction efficiency. Moreover, the low fabrication efficiency and high cost limit the commercial development of 3D display based on metasurface. Here we propose a multiview 3D display based on multi-level pixelated blazed gratings. The period and orientation of each blazed grating in the view modulator is different to form a converged light field. A 4-view prototype was assembled by integrating the view modulator with a shadow mask for the modulation of light intensity. A 3D thoracic cage model was virtually projected within the viewing angle with minimum crosstalk. The light efficiency of the prototype is significantly improved to 60% for 4-level blazed gratings.

Performance improvement of projection-type multiview holographic three-dimensional display using spatial light modulators

Projection-type multiview holographic three-dimensional (3D) display using a single spatial light modulator (SLM) and a directional diffractive device (DDD) composed of pixelated gratings is able to present 3D scenes with wide viewing angle and significantly reduced data volume. However, there are still several limitations on the display performance, such as finite number of viewpoints and low resolution for each view. In this paper, we propose an optimization method of projection-type multiview holographic 3D display by using multiple SLMs and a large-area DDD, where the total valid pixels used for multiview 3D display are substantially increased thanks to the seamless mosaic of holographic reconstructed images of multiple computer-generated holograms (CGHs) displaying on the SLMs so that the display performance can be noticeably improved. Two verification experiments are performed by combining two phase-only SLMs with an 8-view and a 4-view DDDs, respectively. The experimental results confirm that the crosstalk-free multiview holographic 3D displays with more viewpoints or higher resolution are successfully achieved, verifying the effectiveness of the proposed method.

Depth sensitivity investigation on multi-view glasses-free 3D display

Compared with the 2-view 3D display, the multiview 3D display provides more views to the observers, which allows a stereoscopic perception relatively closer to real viewing condition. Depth sensitivity (DS) on multi-view 3D display has not been investigated with respect to view number and stimulus contents. A lenticular glasses-free 3D display with alternative view numbers (2 views and 28 views) was used as the test platform. Two types of stimulus were implemented for DS investigation, including random dot stereogram (RDS) and contour stereogram (CS). 20 adults (22.8 ±2.1 years old) with normal vision participated in the experiment. Experimental results showed that the DS on 2-view display mode was consistent with that measured with the conventional DS test (t-ratio = 0.2560, P=0.8569). Besides, the DS was significantly better for 28-view display mode, compared with 2- view display mode (t-ratio = 4.326, P<0.0001). For the influence of stimulus type, subjects were able to perceive more precise depth information with the RDS (t-ratio=2.023, P=0.0422), compared with the CS. The proposed investigation indicates that depth perception is closely related to view numbers and stimulus content, the proposed investigation provides essential cues for the choice of view numbers and contents to achieve the desired perception effect.

Full-parallax 3D display using time-multiplexing projection technology

We enhanced the resolution characteristics of a threedimensional (3D) image using time-division multiplexing methods in a full-parallax multi-view 3D display. A time-division light-ray shifting (TDLS) method is proposed that uses two polarization gratings (PGs). As PG changes the diffraction direction of light rays according to the polarization state of the incident light, this method can shift light rays approximately 7 mm in a diagonal direction by switching the polarization state of incident light and adjusting the distance between the PGs. We verified the effect on the characteristics of 3D images based on the extent of the shift. As a result, the resolution of a 3D image with depth is improved by shifting half a pitch of a multi-view image using the TDLS method, and the resolution of the image displayed near the screen is improved by shifting half a pixel of each viewpoint image with a wobbling method. These methods can easily enhance 3D characteristics with a small number of projectors.

Quantitative evaluation of perceived depth of transparently-visualized medical 3D data presented with a multi-view 3D display

Transparent visualization is used in many fields because it can visualize not only the frontal object but also other important objects behind it. Although in many situations, it would be very important for the 3D structures of the visualized transparent images to be perceived as they are simulated, little is known quantitatively as to how such transparent 3D structures are perceived. To address this question, in the present study, we conducted a psychophysical experiment in which the observers reported the perceived depth magnitude of a transparent object in medical images, presented with a multi-view 3D display. For the visualization, we employed a stochastic point-based rendering (SPBR) method, which was developed recently as a technique for efficient transparent-rendering. Perceived depth of the transparent object was smaller than the simulated depth. We found, however, that such depth underestimation can be alleviated to some extent by (1) applying luminance gradient inherent in the SPBR method, (2) employing high opacities, and (3) introducing binocular disparity and motion parallax produced by a multi-view 3D display.

Autostereoscopic 3D display system with dynamic fusion of the viewing zone under eye tracking: principles, setup, and evaluation [Invited

We study optical technologies for viewer-tracked autostereoscopic 3D display (VTA3D), which provides improved 3D image quality and extended viewing range. In particular, we utilize a technique-the so-called dynamic fusion of viewing zone (DFVZ)-for each 3D optical line to realize image quality equivalent to that achievable at optimal viewing distance, even when a viewer is moving in a depth direction. In addition, we examine quantitative properties of viewing zones provided by the VTA3D system that adopted DFVZ, revealing that the optimal viewing zone can be formed at viewer position. Last, we show that the comfort zone is extended due to DFVZ. This is demonstrated by a viewer's subjective evaluation of the 3D display system that employs both multiview autostereoscopic 3D display and DFVZ.

23-9 超多眼方式を用いた網膜投影型ヘッドマウント3次元ディスプレイ(第23部門 立体映像技術)

23-9 超多眼方式を用いた網膜投影型ヘッドマウント3次元ディスプレイ(第23部門 立体映像技術)

Multiview holographic 3D dynamic display by combining a nano-grating patterned phase plate and LCD.

Limited by the refreshable data volume of commercial spatial light modulator (SLM), electronic holography can hardly provide satisfactory 3D live video. Here we propose a holography based multiview 3D display by separating the phase information of a lightfield from the amplitude information. In this paper, the phase information was recorded by a 5.5-inch 4-view phase plate with a full coverage of pixelated nano-grating arrays. Because only amplitude information need to be updated, the refreshing data volume in a 3D video display was significantly reduced. A 5.5 inch TFT-LCD with a pixel size of 95 μm was used to modulate the amplitude information of a lightfield at a rate of 20 frames per second. To avoid crosstalk between viewing points, the spatial frequency and orientation of each nano-grating in the phase plate was fine tuned. As a result, the transmission light converged to the viewing points. The angular divergence was measured to be 1.02 degrees (FWHM) by average, slightly larger than the diffraction limit of 0.94 degrees. By refreshing the LCD, a series of animated sequential 3D images were dynamically presented at 4 viewing points. The resolution of each view was 640 × 360. Images for each viewing point were well separated and no ghost images were observed. The resolution of the image and the refreshing rate in the 3D dynamic display can be easily improved by employing another SLM. The recoded 3D videos showed the great potential of the proposed holographic 3D display to be used in mobile electronics.

Diffraction effects incorporated design of a parallax barrier for a high-density multi-view autostereoscopic 3D display.

We present optical characteristics of view image provided by a high-density multi-view autostereoscopic 3D display (HD-MVA3D) with a parallax barrier (PB). Diffraction effects that become of great importance in such a display system that uses a PB, are considered in an one-dimensional model of the 3D display, in which the numerical simulation of light from display panel pixels through PB slits to viewing zone is performed. The simulation results are then compared to the corresponding experimental measurements with discussion. We demonstrate that, as a main parameter for view image quality evaluation, the Fresnel number can be used to determine the PB slit aperture for the best performance of the display system. It is revealed that a set of the display parameters, which gives the Fresnel number of ∼ 0.7 offers maximized brightness of the view images while that corresponding to the Fresnel number of 0.4 ∼ 0.5 offers minimized image crosstalk. The compromise between the brightness and crosstalk enables optimization of the relative magnitude of the brightness to the crosstalk and lead to the choice of display parameter set for the HD-MVA3D with a PB, which satisfies the condition where the Fresnel number lies between 0.4 and 0.7.

Parallax barrier engineering for image quality improvement in an autostereoscopic 3D display.

We present a image quality improvement in a parallax barrier (PB)-based multiview autostereoscopic 3D display system under a real-time tracking of positions of a viewer's eyes. The system presented exploits a parallax barrier engineered to offer significantly improved quality of three-dimensional images for a moving viewer without an eyewear under the dynamic eye tracking. The improved image quality includes enhanced uniformity of image brightness, reduced point crosstalk, and no pseudoscopic effects. We control the relative ratio between two parameters i.e., a pixel size and the aperture of a parallax barrier slit to improve uniformity of image brightness at a viewing zone. The eye tracking that monitors positions of a viewer's eyes enables pixel data control software to turn on only pixels for view images near the viewer's eyes (the other pixels turned off), thus reducing point crosstalk. The eye tracking combined software provides right images for the respective eyes, therefore producing no pseudoscopic effects at its zone boundaries. The viewing zone can be spanned over area larger than the central viewing zone offered by a conventional PB-based multiview autostereoscopic 3D display (no eye tracking). Our 3D display system also provides multiviews for motion parallax under eye tracking. More importantly, we demonstrate substantial reduction of point crosstalk of images at the viewing zone, its level being comparable to that of a commercialized eyewear-assisted 3D display system. The multiview autostereoscopic 3D display presented can greatly resolve the point crosstalk problem, which is one of the critical factors that make it difficult for previous technologies for a multiview autostereoscopic 3D display to replace an eyewear-assisted counterpart.