【作者】 夏新星；

【导师】 李海峰； 刘旭；

【作者基本信息】 浙江大学 ， 光学工程， 2014， 博士

【摘要】 光场三维显示技术是近几年才被提出的一种新型三维显示方法。这种技术试图记录和重构三维物体上各个点元朝向各个方向发出的光线,与全息显示类似,因此它不仅可以真实再现三维场景的空间特性,而且能够正确表现不同物体的相互遮挡关系,是一种更符合人们观看习惯的三维显示技术,已经成为近年来的研究热点。本论文以全光函数为基础,围绕着光场重构这一问题进行展开,阐述了光场三维显示的基本原理,着重介绍了三套分别采用普通定向散射屏、柱面定向散射屏以及平面偏折型定向散射屏实现360度水平光场三维显示系统的基本结构、重建原理,并详细分析了这三套系统的三维显示空间以及单一视点观看图像。这为光场三维显示实验样机的成功构建和后续性能评价提供了重要的理论依据。我们搭建了基于数字微镜阵列(DMD)的彩色高速投影样机,开发了具有特定散射特性的定向散射屏,解决了光场数据采集以及计算、投影图像的快速生成、海量数据的高效压缩与高速传输以及光场扫描的图像同步控制等关键问题,成功地先后构建了基于普通定向散射屏的360度光场三维显示系统以及基于平面偏折型定向散射屏的悬浮式360度光场三维显示系统。实验系统既证明了利用高速投影机和同步旋转的定向散射屏来进行360度光场三维显示的可行性,又为进行光场三维显示性能评价的深入研究提供了有效平台。构建的悬浮式360度光场三维显示,首次成功地将显示的三维场景完全悬浮在屏幕上方的空气中,这为今后观察者用手探入显示区域与三维场景进行实时交互奠定了基础。随着三维显示相关研究的深入,评价再现三维图像的显示性能将会成为下一步研究的主要方向。基于构建的实验平台,分析了光场三维显示的空间再现能力,提出了空间分辨率以及角分辨率的计算方法,并从信息量的角度,提出并分析了光场显示所具有的光线复用特性。我们还提出了表示精确度的函数用于评价光场重建的精确程度,为进一步地评价三维显示图像质量提供了理论指导。另外,我们在现有实验平台的基础上对显示系统性能进行了一定的改进与提升。我们提出了基于LED亮度调制的真彩色光场三维显示方法并进行了实验验证,在显示二值图像数量相同的情况下,显著地提高了重建灰度的量级。基于目前的数据传输系统,我们还初步研究了基于手势的三维交互方法,并通过原理实验进行验证。最后,展望了光场三维显示的发展前景。基于现有实验系统的不足,从显示器件、屏幕器件、垂直自由视点、图像实时生成及海量数据传输、三维显示图像评价体系以及视觉感知的生理心理学等诸多方面进行了分析,为今后光场三维显示的研究和发展提供了方向。更多还原

【Abstract】 Light field three-dimensional (3D) display technique, which was proposed several years ago, is one of the novel3D displays. This technique, similar to holographic display, tries to record and reconstruct the rays in different directions emitting from every point of3D objects. Therefore, it can not only reconstruct the spatial property of3D scenes really, but also represent the occlusion relation between different objects correctly. Since light field display conforms with the human vision, it has become one of the research hotspots in recent years.Based on the plenoptic function, the thesis involves the issue of light field reconstruction. After brief introduction of the principle of light field display, rotating directional diffuser, cylindrical directional diffuser and flat light field directional diffuser are utilized to develop360-degree light field display system respectively. The configuration and reconstruction method of these three types of3D displays are highlighted, and the3D display zone and image observed at one viewpoint are analyzed in detail. It provides theoretical references for establishment of light field3D display prototypes and subsequent performance evaluation.We developed the color high-frame-rate DMD-based projector, and designed the directional diffuser with featured diffusing characteristics. Then we solved the key problems including acquisition and computation of light field, rapid generation of projecting images, efficient compression and high-speed transmission of mass data, synchronization of scanning light field, and so on.360-degree light field3D display system based on rotating directional diffuser and flat light field directional diffuser were built successively. The experimental systems demonstrate the feasibility of the method which is utilizing high-frame-rate projector and synchronously rotating directional diffusing screen to achieve360-degree light field3D display, and provides an effective platform to further study the performance of light field3D display. The floating360-degree floating3D display made the whole displayed3D scenes floating over the flat light field directional diffuser in the air successfully for the first time. It establishes the foundation for the further study of real-time interaction with the reconstructed3D scenes.With the further development of3D display, the performance evaluation of displayed3D image is gradually becoming the direction of the next research. Based on the experimental platform, the spatial reconstruction ability was analyzed in detail, and computational method of the spatial resolution and angular resolution was presented. From the perspective of amount of information, the characteristic of ray multiplexing was proposed and analyzed. Besides, we presented the evaluation function of the accuracy of light field reconstruction, which provides theoretical guidance for further evaluation of displayed3D images. We also improved the proposed display system in some respects. The method of true-color light field3D display based on LED luminance modulation was presented. And the experimental result showed that the method could increase the gray scale significantly with the same number of projecting binary images. Based on the current data transmitting system, the method of gesture-based3D interaction was initially researched, and the experimental results verified this method.At last, we have discussed the development of light field3D display. Based on the existing deficiency of experimental system, we analyzed on many aspects, such as display device, screen device, vertical free viewpoint, real-time image generation and mass data transmission, evaluation system of3D image, physiology and psychology of visual cognition and so on. It shows us a research direction of future research and development.更多还原