【作者】 黄治；

【导师】 白剑；

【作者基本信息】 浙江大学 ， 测试计量技术及仪器， 2014， 博士

【摘要】 全景环带光学成像系统是一种特殊的超广角光学系统,进入系统的光线经多次反射和折射进入转向镜组,并最终成像在传感器上。这种系统能在保持结构体积紧凑的前提下将360。视场的物体按柱面投影的方式映射到一个环状平面上,在全景监控,管道探测等领域都有较为广阔的应用前景。普通传感器获得的都是二维的图像信息,拍摄者与之间物体的距离信息在投影过程中丢失,而立体成像是一种依靠多镜头或是多次拍摄来还原立体信息的方法,能在获取平面图像的同时获取物体的距离信息。传统的立体视觉都只针对某一个特定的方向,无法做到实时的采集周视环境的三维立体信息,为了实现某些需要无死角三维信息实时采集的需求,传统的方法往往需要精密的光学设备与复杂的后期图像处理的过程。本文提出的利用全景环带光学系统实现单传感器立体信息获取的设备与方法即可以解决以上的问题,采用两个同轴放置的全景环带透镜,在无遮拦的情况下成在同一个像面上。上方单元成像在下方单元的盲区中,且成像区域互不影响。此外,为了解决实验中的杂散光问题,还提出了一系列在优化设计中即可抑制全景环带透镜杂散光的方法,并都予以了实验验证。本文的研究内容主要包括以下几个方面：1.介绍了全景立体成像的研究背景,大视场成像技术和传统立体视觉获取设备的分类、发展现状、几种典型实例以及各自的优缺点。将全景和立体视觉相结合产生的集中光学系统和其基本原理,引出了一种基于全景环带透镜的独特成像方式,以及其较有潜力的应用领域。2.对全景环带透镜的有关参数结构之间的约束关系给出具体的数学表达关系,推导了主光线与各个表面交点的通用表达式,对优化设计的方法予以概括,提出了针对全景环带透镜的评价方法,最后综合其特点给出了全景环带透镜较有前景的几类应用领域。3.提出全景立体成像系统的基本成像原理,并建立了相应数学模型。详细介绍了上下全景环带透镜单元的设计步骤,设计制造了一套原理样机,并成功获得预期的图像。4.对立体信息的提取过程进行了详细介绍,给出了因入瞳漂移导致的基线长度变化的解决方案,采用多项式拟合的方法得到了快速确定入射角与基线长度的方法。在图像处理方面,给出了图像展开算法与相关点匹配算法,最后用实验验证了该系统分辨周视物体距离的能力,并给出了误差分析。5.提出了基于全景环带透镜的杂散光分析与抑制的方法,给出了详细的数学建模方法与抑制原则,并将其写入优化函数,设计制造了一套能够抑制杂散光的全景环带透镜,并与光学参数相同的普通全景系统进行了软件仿真与实物测试两种对照,最终都可以验证本文提出的设计原则可有效抑制全景光学系统中的杂散光。更多还原

【Abstract】 Panoramic annular lens system is one of the specific wide angle lenses. After several reflectitons and refractitions, the rays get into the relay lens and image on one sensor. This kind of optical system can project360°field of view onto a cicular image according to the cylinder projecting principle and the size of the system keeps compact. So it has a great application potential in the fields like panorama supervisory and pipe detection.The CCD/COMS sensors can only obtain two-dimensional information. The distance information of the objects in the image is lost in the projecting process. To obtain three-dimensional information, the traditional methods are using two or more lenses or take several pictures in different place to restore the depth information. The traditional binocular vision system is highly developed, but the observation angle of this system is narrow. It cannot obtain the panorama view of object space. So, to satisfy some applications that need360°field of view without any dead angle, people proposed several solutions, but most of them need complicate optical structure or image processing progress.In this paper, a novel real-time stereo system using double co-axial PALs is proposed. The method to extract the depth information is also present. The images of two units are on the same sensor without any overlay, and one circle image is on the other’s blind area. Besides, to eliminate the stray light in the experiment, some special criterions are added into the optimizing process. The simulation and real experiment both prove that the eliminating result is well. The detailed research contents are listed as below:1) The panoramic stereo imaging reaserch background, the technology of wild field of view, the category of the traditional stereo equipments, the present development situation, some typical examples and their advantages and disadvantages are introduced in the first chapter. After that, we put panoramic and stereo together and invent an optical system called panoramic stereo imaging system. This system has a particular imaging principle.2) The relationship of the geometry parameter and the constraint condition is established. After that, we trace the chief ray and obtain the point of intersections on the four surfaces and deduce some universal expressions. We summarize the optimizing methods and propose the evaluating criterion in the panoramic annular lens. Finally, we give some potential application field using this kind of lens.3) The panoramic stereo system’s imaging principle is proposed and the mathematical model is established. Also, we describe the detailed process of how to deign the two panoramic annular lens units, make a prototype and capture the prospective pictures.4) The extracting process of depth information from the picture getting by the above optical system is proposed. We analyze the baseline change caused by the pupil shifting and the solution to this problem. Using the fitting of a polynomial, we can quickly determine the relationship between the baseline’s length and the incident light angles. In the image process, we describe the ways to straighten the picture and match the feature point. In the end, we measure theprecsion of the system’s spatial resolution capability by a prototype and analysis the possible sources of the testing error. 5) A novel stray light evaluation method and some suppression principles of panoramic annular lens system in theory are proposed. By adding stray light suppression optimization function into optical software, a new panoramic annular lens system is designed. The high stray light suppression performance of this system is shown by non-sequential optical simulation software and real experiment compared with a normal panoramic annular lens system which shows its better stray light suppression performance than the normal one.更多还原