Autostereoscopic Research Articles

Display depth analyses with the wave aberration for the auto-stereoscopic 3D display

Because the aberration severely affects the display performances of the auto-stereoscopic 3D display, the diffraction theory is used to analyze the diffraction field distribution and the display depth through aberration analysis. Based on the proposed method, the display depth of central and marginal reconstructed images is discussed. The experimental results agree with the theoretical analyses. Increasing the viewing distance or decreasing the lens aperture can improve the display depth. Different viewing distances and the LCD with two lens-arrays are used to verify the conclusion.

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.

Comparison of visual discomfort when viewing 3D videos with various contrast changes on a stereoscopic 3D display, an autostereoscopic display, and an HMD

The increasing popularity of different kinds of 3D displays such as stereoscopic 3D monitors, auto-stereoscopic displays, and head mounted displays (HMDs) has led to visual discomfort being considered as one of the major concerns in the 3D industry. Previous research studies on visual discomfort have considered various disparities and motions in 3D videos to identify vergence-accommodation linkage conflicts. In this paper, we measure visual discomfort occurring from viewing 3D videos with various contrast changes using perceived symptoms questionnaires, measured near point of convergence, eye blink rate, and saccadic movements. We compare visual discomfort for different displays such as stereoscopic 3D (s3D) display, auto-stereoscopic display, and HMD. From our experimental results, we conclude that visual discomfort increases when the subject is watching 3D videos using auto-stereoscopic displays. In addition, brighter videos caused more visual discomfort compared to darker videos.

360-degree Multi-Viewer Autostereoscopic Tabletop Display with Omnidirectional Dynamic Parallax Barrier and Novel Time-Multiplexed Directional Backlight

The goal of this project is to develop an autostereoscopic tabletop display for multiple viewers freely positioned around the display. 3D content is produced by an omnidirectional dynamic parallax barrier display using dual layer transparent LCD panels. Time multiplexing the parallax barrier’s period and orientation, and the use of a directional backlight allows for displaying 3D content 360° around the table to multiple tracked viewers. The novel directional backlight provides precise addressability of a large number of views using a hemispherical mirror to collimate light from a concentric outwards facing hemispherical LED array. A prototype was built using two 27” 2560×1440 pixel resolution LCD displays with 144Hz refresh rates. Interactive content and dynamic parallax barriers are rendered in a Unity 3D game engine based upon viewer positions obtained from a Vicon tracking system and a Kalman filter. The addressable backlight consists of 216 LEDs, addressable in 36 rows 10° apart placed on a transparent 38cm (15”) wide hemisphere inside a 76cm (30”) hemispherical concave mirror.

다시점 영상처리를 이용한 무안경 3차원 디스플레이의 크로스톡 저감 방법

본 논문은 다시점 영상처리 기술을 이용하여 무안경 3차원 디스플레이의 크로스톡(Crosstalk)을 저감하는 새로운 방법을 제안한다. 크로스톡은 현 시점 영상 정보를 주변 시점 영상 정보와 섞여 보이게 하여 출력 3차원 영상을 매우 흐리게 만든다. 무안경 3차원 디스플레이의 크로스톡을 저감하기 위해, 제안한 방법은 다시점 영상에 적응적 깊이 재배치와 시점 미분값 기반 크로스톡 역보상 필터를 적용한다. 또한, 제안한 방법은 에피폴라 영상 화소 보간법을 이용하여 넘침 및 아래 넘침 화소를 보상하여 영상 왜곡을 최소화한다. 실험 결과는 제안한 방법이 기존 방법보다 3차원 영상 품질을 향상시키면서 크로스톡을 효율적으로 저감함을 보여준다. In this paper, we present a new method to reduce crosstalk of a glasses-free three-dimensional (3D) display using a multi-view image processing technique. Since crosstalk makes the current view image mixed with its neighboring ones, the output 3D image becomes severely blurred. We apply adaptive depth retargeting and view gradient-based crosstalk inverse filtering onto a multi-view image to minimize crosstalk of the glasses-free 3D display. In addition, overflow and underflow pixels are compensated by epipolar image pixel interpolation so that visual artifacts are minimized. Experimental results show that the proposed method reduces crosstalk more efficiently than the previous work while improving 3D image quality.

Directional backlight 3D display system with wide-dynamic-range view zone, high brightness and switchable 2D/3D

In this paper, we present an autostereoscopic display system with wide-dynamic-range view zone, high brightness and switchable 2D/3D. For this purpose, we propose a novel directional backlight system inspired by an optical splitter. Combined with eye tracking technique and LED-lit matrix, we expand the viewing zone and achieve 2D/3D switchable properties. And the design of direct illumination-type LED backlight improves the brightness significantly. The mathematical analysis and logic principle of the system is provided in this paper. And also, we build an autostereoscopic display prototype by the directional backlight system, and demonstrate experimentally that our system gives the viewer freedom both of viewing position and viewing environment with images of high quality.

超多視点裸眼立体ディスプレイのためのインタラクティブコンテンツの制作および実行環境の構築

超多視点裸眼立体ディスプレイのためのインタラクティブコンテンツの制作および実行環境の構築

Novel corrective machining method to fine-tune groove widths

Using lenticular lenses to realize auto-stereoscopic displays has become increasingly popular in the TV industry, especially in the area of developing multi-view glasses-free 3D TV. Each lenticular lens has many sublenses through which the light is diverted in different directions. A multi-view TV display projects a vertically rotated 3D image to a viewer that seamlessly matches his or her sideways movement. To do so, it poses a very stringent requirement on machining lenticular lens mold. Using a tailor-made cutting tool, the profile of the lenticular grooves can be machined very precisely, and in a very efficient manner; however, the groove width might vary due to elastic bouncing. Such variation of the groove width leads to disparity in the light intensity entering the left and right eye of the viewer. The 3D perception would then unavoidably deteriorate. Thus, a corrective machining method must be developed to fine-tune the groove width. In this paper, a method involving transverse cutting perpendicular to the axes of the lenticular grooves is proposed, in which the cutting is done transversely across the grooves using a single point diamond tool. The depth of corrective cut is 1 μm, and the errors in the groove widths can be corrected to ±200 nm.

Approach to change optimal viewing distance of autostereoscopic display based on parallax barrier

Abstract An approach to change the optimal viewing distance of autostereoscopic is proposed. The optimal viewing distance can be changed by setting up a prism array instead of changing the parameters of the display. The theoretical formula to determine the optimal viewing distances are deduced and prism array structure is designed. The parameters of the prism array are optimised. The simulation results by optical analysis software ASAP show that this approach is correct and feasible.

Parallax adjustment for visual comfort enhancement using the effect of parallax distribution and cross talk in parallax-barrier autostereoscopic three-dimensional display

Visual discomfort is a common problem in three-dimensional (3D) videos, and this issue is the subject of many current studies. Among the methods to overcome visual discomfort presented in current research, parallax adjustment methods provide little guidance in determining the condition for parallax control. We propose a parallax adjustment based on the effects of parallax distribution and cross talk on visual comfort, where the visual comfort level is used as the adjustment parameter, in parallax-barrier-type autostereoscopic 3D displays. We use the horizontal image shift method for parallax adjustment to enhance visual comfort. The speeded-up robust feature is used to estimate the parallax distribution of 3D sequences, and the required amount for parallax control is chosen based on the predefined effect of parallax distribution and cross talk on visual comfort. To evaluate the performance of the proposed method, we used commercial 3D equipment with various intrinsic cross-talk levels. Subjective tests were conducted at the fixed optimal viewing distance for each piece of equipment. The results show that comfortable videos were generated based on the proposed parallax adjustment method.

Tri-color composite volume H-PDLC grating and its application to 3D color autostereoscopic display.

A tri-color composite volume holographic polymer dispersed liquid crystal (H-PDLC) grating and its application to 3-dimensional (3D) color autostereoscopic display are reported in this paper. The composite volume H-PDLC grating consists of three different period volume H-PDLC sub-gratings. The longer period diffracts red light, the medium period diffracts the green light, and the shorter period diffracts the blue light. To record three different period gratings simultaneously, two photoinitiators are employed. The first initiator consists of methylene blue and p-toluenesulfonic acid and the second initiator is composed of Rose Bengal and N-phenyglycine. In this case, the holographic recording medium is sensitive to entire visible wavelengths, including red, green, and blue so that the tri-color composite grating can be written simultaneously by harnessing three different color laser beams. In the experiment, the red beam comes from a He-Ne laser with an output wavelength of 632.8 nm, the green beam comes from a Verdi solid state laser with an output wavelength of 532 nm, and the blue beam comes from a He-Cd laser with an output wavelength of 441.6 nm. The experimental results show that diffraction efficiencies corresponding to red, green, and blue colors are 57%, 75% and 33%, respectively. Although this diffraction efficiency is not perfect, it is high enough to demonstrate the effect of 3D color autostereoscopic display.

A cross-platform solution for light field based 3D telemedicine

Current telehealth services are dominated by conventional 2D video conferencing systems, which are limited in their capabilities in providing a satisfactory communication experience due to the lack of realism. The “immersiveness” provided by 3D technologies has the potential to promote telehealth services to a wider range of applications. However, conventional stereoscopic 3D technologies are deficient in many aspects, including low resolution and the requirement for complicated multi-camera setup and calibration, and special glasses. The advent of light field (LF) photography enables us to record light rays in a single shot and provide glasses-free 3D display with continuous motion parallax in a wide viewing zone, which is ideally suited for 3D telehealth applications. As far as our literature review suggests, there have been no reports of 3D telemedicine systems using LF technology. In this paper, we propose a cross-platform solution for a LF-based 3D telemedicine system. Firstly, a novel system architecture based on LF technology is established, which is able to capture the LF of a patient, and provide an immersive 3D display at the doctor site. For 3D modeling, we further propose an algorithm which is able to convert the captured LF to a 3D model with a high level of detail. For the software implementation on different platforms (i.e., desktop, web-based and mobile phone platforms), a cross-platform solution is proposed. Demo applications have been developed for 2D/3D video conferencing, 3D model display and edit, blood pressure and heart rate monitoring, and patient data viewing functions. The demo software can be extended to multi-discipline telehealth applications, such as tele-dentistry, tele-wound and tele-psychiatry. The proposed 3D telemedicine solution has the potential to revolutionize next-generation telemedicine technologies by providing a high quality immersive tele-consultation experience.

Subjective Comparison of Consumer Television Technologies for 3D Visualization

This paper presents a comparison among different consumer 3D display technologies by means of a subjective assessment test. Therefore, four 55-in displays have been considered: one autostereoscopic display, one stereoscopic with polarized passive glasses, and two with active shutter glasses. In addition, a high-quality 3D video database has been used to show diverse material with both views in high definition. To carry out the test, standard recommendations have been followed considering also some modifications looking for a test environment more similar to real home viewing conditions, with the objective of obtaining more representative conclusions. Moreover, several perceptual factors have been considered to study the performance of the displays, such as picture quality, depth perception, and visual discomfort. The obtained results show interesting issues, like the performance improvement of active shutter glasses technology, the high performance of the polarized glasses technology in terms of quality and comfort, and the need of improvement of the autostereoscopic displays to complement the visual comfort to reach a global high-quality visual experience.

Floating autostereoscopic 3D display with multidimensional images for telesurgical visualization.

We propose a combined floating autostereoscopic three-dimensional (3D) display approach for telesurgical visualization, which could reproduce live surgical scene in a realistic and intuitive manner. A polyhedron-shaped 3D display device is developed for spatially floating autostereoscopic 3D image. Integral videography (IV) technique is adopted to generate real-time 3D images. Combined two-dimensional (2D) and 3D displays are presented floatingly around the center of the display device through reflection of semitransparent mirrors. Intra-operative surgery information is fused and updated in the 3D display, so that telesurgical visualization could be enhanced remotely. The experimental results showed that our approach can achieve a combined floating autostereoscopic display that presents 2D and 3D fusion images. The glasses-free IV 3D display has full parallax and can be observed by multiple persons from surrounding areas at the same time. Furthermore, real-time surgical scene could be presented and updated in a realistic and intuitive visualization platform. It is shown that the proposed method is feasible for facilitating telesurgical visualization. The proposed floating autostereoscopic display device presents surgical information in an efficient form, so as to enhance operative cooperation and efficiency during operation. Combined presentation of imaging information is promising for medical applications.

Effects of depth perception cues and display types on presence and cybersickness in the elderly within a 3D virtual store

As the population ages, home computers with an Internet connection can provide the elderly with a new way to access information and services and manage Internet shopping tasks. One of the primary advantages of virtual environment (VE) technology for online shopping is its ability to provide a three-dimensional (3D) perspective to customers for a more realistic sense of the goods and the shopping environment. A sense of presence is one of the critical components required for an effective VE. However, side effects such as cybersickness may be caused by the display medium. When the quality of depth perception cues is poor, will the elderly’s experience of cybersickness influence their feeling of presence and performance of goods searching during exposure within a 3D virtual store with 3D displays? An experiment addressed associations among presence, cybersickness, and performance in a 3D virtual store with autostereoscopic, stereoscopic and monocular displays with good and poor depth perception cues in an elderly sample. The results showed that the virtual store with an autostereoscopic display with high-quality depth perception cues will produce good sense and realism in stereopsis to allow the elderly to experience presence within a virtual store. However, if the depth perception cues are poor, 3D displays, and especially stereoscopic displays, are not recommended; elderly users may lose interest in a 3D virtual store due to even more serious cybersickness than that experienced with a monocular display.

Round-view autostereoscopic display based on an adaptive subpixel pre-rendering tracking algorithm

A round-view autostereoscopic display is proposed based on an adaptive subpixel pre-rendering (ASPR) tracking algorithm. In the ASPR-based round-view system, 3D scene is rotated adaptively in a floating viewing zone by changing parallax image array (PIA) in real-time corresponding to the viewer's position. To verify and evaluate the achievements, an ASPR-based round-view autostereoscopic display prototype is developed. The results in both quality and quantity show that a round-view 3D perception is achieved in 90° ortho-stereoscopy viewing angle without pseud-3D effect, viewing zone flipping, and time delay.

The world's first radical resection for lung cancer using glasses-free 3D thoracoscope was completed in Guangzhou.

There is no boundary for a walker and no end of journey for an explorer. On May 5, 2015, Prof. He Jianxing from the First Affiliated Hospital of Guangzhou Medical University, with his team performed the world’s first two cases of radical lung cancer resection using glasses-free 3D thoracoscope, opening the door to further innovations to advance medical development ( Figure 1 ).

The world's first radical resection for lung cancer using glasses-free 3D thoracoscope was completed in Guangzhou.

There is no boundary for a walker and no end of journey for an explorer. On May 5, 2015, Prof. He Jianxing from the First Affiliated Hospital of Guangzhou Medical University, with his team performed the world’s first two cases of radical lung cancer resection using glasses-free 3D thoracoscope, opening the door to further innovations to advance medical development ( Figure 1 ).

Improving workflows of neuro-interventional procedures with autostereoscopic 3D visualization of multi-modality imaging in hybrid interventional suites.

Recent developments in interventional neuroradiology techniques, medical imaging modalities, endovascular stenting and embolization materials lead to an increasing number of patients with cerebral aneurysms and arteriovenous malformations that are eligible for endovascular treatment and have opened new perspectives for novel ways for patient treatment in general. In this paper, we describe a software tool for 3D image fusion of multi-modal acquisitions to assist endovascular treatment of cerebral malformations. The software and an autostereoscopic 3D display were implemented and tested in clinical applications in a hybrid interventional suite that is used for radio-interventional as well as neurosurgical procedures. Our hypothesis is that fusion of image data acquired prior to intervention procedures with images acquired during those procedures should allow better visualizing and navigating through complex cerebral vasculature. This should also improve workflows of neuro-interventional procedures. Preoperative and intra-operative acquisitions of vascular images of the brain were performed and transferred to a dedicated imaging workstation to be processed with our image fusion and visualization software tool. The tool was developed as a plugin extension to the open-source DICOM viewer OsiriX and is based on a modular and scalable architecture. Several processing modules were implemented to allow spatial co-registration and fusion of preoperative and intra-operative modalities. A special extension was also implemented for interactive autostereosopic, glass-free 3D visualization of fused results. The software platform was validated and evaluated in nine in vivo procedures by expert users. All patient cases were related to interventional treatment of neuro-vascular diseases. The emphasis was laid on the added value of spatial co-registration and fusion of preoperative and intra-operative modalities, as well as the overall impact on workflow during the intervention. The co-registered and fused images were visualized on an autostereoscopic 3D monitor installed in hybrid interventional suite. All experiments were evaluated and scored by interventional physicians and technicians. Displaying 3D-4D representations of brain vascular anomalies based on multi-modal acquisitions on a 3D autostereoscopic display is beneficial for the workflow and efficiency of interventional radiologists. The implemented software tool fulfills the premise of applicability of an open-source platform for more advanced, multi-modal visualization and processing of brain vascular structures for image-guided therapeutic interventions.

An innovative calibration based integral photography rendering algorithm for medical application and its evaluation.

Autostereoscopic has long been proposed to fulfill medical display in image-guided surgery and clinical education to provide more intuitive position information of clinical interest zone thus improving surgery safety and accuracy. As one category of flexible autostereoscopic 3D display, computer generated integral photography (CGIP) has been studied in medical application by many researches for its convenience and cost-efficiency. However, IP still suffers from inaccurate light field reconstruction, which limits its practicality in surgery. In this paper, we propose and apply a flexible fish-eye model based micro lens array (MLA) distortion calibration method and pre-distorted retracing rendering algorithm to render elemental image array (EIA) of CGIP. Furthermore, we also evaluate light field of the proposed algorithm in depth cue, and signal noise ratio of IP images by phantom experiment.