Author Affiliations
Abstract
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications (BUPT), Beijing 100876, China
A concept of divergence angle of light beams (DALB) is proposed to analyze the depth of field (DOF) of a 3D light-field display system. The mathematical model between DOF and DALB is established, and the conclusion that DOF and DALB are inversely proportional is drawn. To reduce DALB and generate clear depth perception, a triple composite aspheric lens structure with a viewing angle of 100° is designed and experimentally demonstrated. The DALB-constrained 3D light-field display system significantly improves the clarity of 3D images and also performs well in imaging at a 3D scene with a DOF over 30 cm.
3D light-field display depth of field divergence angle of light beams compound lens Chinese Optics Letters
2024, 22(1): 011101
针对当前3D光场手势交互存在识别率低、识别速度慢、深度学习网络需要较多数据样本的问题,本文提出了一种基于小样本手部关键点的多层感知器(Multi-Layer Perceptron,MLP)网络提升3D光场交互准确度方法,识别速度达到毫秒级。在手部关键点采集过程中,从不同位置采集得到的同一种手势关键点三维数据存在显著差异。为了消除差异,本文提出在同一右手笛卡尔坐标系下,通过位移和罗德里格旋转公式对简化后的手势模型进行位姿变换,将同一种手势归一化。一个MLP神经网络被用来从归一化后的手部关键点跳变关系中提取手部特征。实验结果表明,本文提出的方法对3D光场交互中的简单手势识别率为95%以上,对复杂手势的识别率为90%以上。与此同时,该方法在小样本数据集训练下表现出优秀的性能,能够满足精确和快速手势识别的要求。最后,本文展示了一种将所提出的方法成功应用于3D光场交互的场景。
交互 手势分类识别 多层感知器 小样本数据集 interaction gesture recognition MLP small dataset
在裸眼3D立体视频观看中,由于存在辐辏调节的矛盾,观看者会产生诸如眩晕、呕吐等视疲劳症状,尤其在医疗、A/VR等场景下,3D视频观看通常为任务驱动,眼动行为由于受到主观控制,单一的眼动特征很难准确评估视觉疲劳,更无法得到视疲劳等级,导致视疲劳无法及时被发现,从而造成不可预估的损失。针对以上问题,本文提出了一种基于多种眼动行为的3D视疲劳等级评估模型,旨在观看3D内容时,通过对注视、扫视、眨眼等眼动行为进行建模分析,得到实时视疲劳等级。本文采用主客观相结合的方法进行实验:受试者观看3D内容,实验人员记录受试者主观打分并利用眼动仪提取受试者客观眼动行为;通过进行相关性分析,探究任务驱动下能够表征3D视疲劳的各种客观眼动行为;利用神经网络建立基于16种眼动行为的视疲劳四等级评估模型。模型对3D视疲劳等级的预测准确率达到82%,证明了模型的有效性。
裸眼3D显示 视疲劳 眼动行为 任务驱动 神经网络 naked eye 3D display eye fatigue eye movements task driving neural network
Author Affiliations
Abstract
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
In the integral imaging light field display, the introduction of a diffractive optical element (DOE) can solve the problem of limited depth of field of the traditional lens. However, the strong aberration of the DOE significantly reduces the final display quality. Thus, herein, an end-to-end joint optimization method for optimizing DOE and aberration correction is proposed. The DOE model is established using thickness as the variable, and a deep learning network is built to preprocess the composite image loaded on the display panel. The simulation results show that the peak signal to noise ratio value of the optimized image increases by 8 dB, which confirms that the end-to-end joint optimization method can effectively reduce the aberration problem.
integral imaging diffractive optical element end-to-end optimization deep learning network aberration correction Chinese Optics Letters
2022, 20(12): 121101
1 北京邮电大学电子工程学院,北京 100876
2 中国人民解放军63867部队,北京 137001
提出了一种基于视点分段式体像素的大视角全视差桌面式光场显示系统,采用了定向准直背光和反贴于分辨率为7680 pixel×4320 pixel的液晶显示屏上的柱镜阵列,实现了100°的水平观看视角,并利用光学偏折膜和全息功能屏,在适用于桌面显示的正面观看范围内实现了离散采样光场的体像素重建。设计了一种能够根据多位观看者的空间坐标划分独立视区的视点分段式体像素,并推导了其与液晶显示屏上子像素的函数映射关系,实现了对观看区域的分段式图像编码。提出了一种可为处在不同观看区域的多位观看者同时提供正确全视差光场显示的透视关系校正方法,填补了光学系统固有的垂直视差缺失,实现了桌面式光场显示中错误透视关系的自适应实时校正。
全息 光场 三维显示系统 视点分段式体像素 全视差 透视关系校正
Author Affiliations
Abstract
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
A holographic visualization of volume data based on adjustable ray to optical-wave conversion is presented. Computer-generated holograms are generated by emitting multiple rays to sample the volumetric field. Equal interval sampling, object light wave adjustment, and information composition are sequentially performed during the march of rays. The program is accelerated in parallel to reduce the total time, and the reconstructions are dynamically adjusted to express different parts of an object. Optical experiments verify that the proposed method can holographically reconstruct the surface and interior information of objects.
computer-generated hologram holographic display ray-casting method volume data visualization Chinese Optics Letters
2022, 20(1): 010501
Author Affiliations
Abstract
State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
A distortion correction method for the elemental images of integral imaging (II) by utilizing the directional diffuser is demonstrated. In the traditional II, the distortion originating from lens aberration wraps elemental images and degrades the image quality severely. According to the theoretical analysis and experiments, it can be proved that the farther the three-dimensional image is displayed from the lens array, the more serious the distortion is. To analyze the process of eliminating lens distortion, one lens and its corresponding elemental image are separated from the traditional II. By introducing the directional diffuser, the aperture stop of the separated optical system changes from the eye’s pupil to the lens. In terms of contrast experiments, the distortion of the improved display system is corrected effectively. In the experiment, when the distance between the reconstructed image and lens array is equal to 120 mm, the largest lens distortion is decreased from 46.6% to 3.3%.
080.1005 Aberration expansions Chinese Optics Letters
2018, 16(4): 041001