标题: | 精准且有自适能力之环场视觉 技术及应用之研究 A study on accurate and adaptive omni-vision techniques and applications |
作者: | 石神恩 Shih, Shen-En 蔡文祥 Tsai, Wen-Hsiang 资讯科学与工程研究所 |
关键字: | 环场视觉;最佳化系统组态;自动调适;Omni-vision;Optimal system cofiguration;Automatic Adaptation |
公开日期: | 2013 |
摘要: | 为了能使电脑与四周环境互动,环场视觉是一项极其有效且十分重要的技术。与传统电脑视觉技术相比,环场视觉强调其在单一时间点能对大范围环境取景之能力,而不用在摄影机上加装马达装置来周期性地转移摄影机,更不需用多部摄影机来对环境取景。由上述可知,在环场视觉技术中我们可以避免影像接合、摄影机换手、多摄影机特征连续追踪等复杂问题。为了达到大范围取景之目的,有两种特殊设计的环场摄影机较常被使用,其一是反射式环场摄影机,另一种是鱼眼摄影机。其中,前者是将一个特殊形状的反射式镜面摆放在一传统摄影机前方,藉由该镜面来研展摄影机的可视范围;后者是利用一特殊的鱼眼透镜来研展其可视范围。然而,因为极大范围的环境资讯被浓缩于一张传统大小的影像中,环场摄影机所撷取到的影像必定有十分严重的扭曲,这也使得后续影像分析的工作变得困难且复杂许多。虽然将影像扭曲校正回来是其中一种简单的解决方式,然而因为扭曲造成影像解析度的不同,校正回来的影像在某些区域会十分地模糊,在影像分析后会产生不稳定的结果。更甚者,上述扭曲校正的过程也需要些许运算能力,在即时应用及嵌入式系统中都较不适用。 为了克服环场摄影机撷取到的严重扭曲,我们提出了在扭曲影像上精准且稳定地侦测空间中直线的方法。另外,我们也针对各种利用环场摄影机侦测空间中直线的应用,提出改良的摄影机模型,并且也提出一套方便的校正程序来校正环场摄影机。此校正程序只需使用空间中的一条直线特征,且不需要测量其位置及方向,使得整个校正程序变得十分简单,且可让一般使用者方便地进行校正,使环场视觉技术朝消费电子更迈进一步。 另外,从消费者的角度上来看,我们应该也要能让一般使用者方便地架设一套环场视觉系统。在此方面,我们提出一套新的双眼视觉系统,此系统可让使用者任意地摆放两部环场摄影机。在摆放完成后,系统会自动利用环境中之直线特征来回推摄影机的位置及角度,从而正确地计算立体资讯,以供各种人机互动应用使用。另一方面,针对需要取得十分精准之立体资讯的应用中,我们也提出一套最佳化架构以及三个最佳化演算法,其可告诉使用者如何摆放该二部环场摄影机的位置及角度,以求得最佳之立体资讯。根据这些最佳化演算法,使用者将可建构出能进行精准立体测量之双眼环场视觉系统。 最后,我们也对上述所提出之各种环场视觉技术进行延伸研究,开发一套室内停车场管控系统。此系统可利用假设于天花板之各环场摄影机,自动地分析停车场中各停车格之位置,并自动找出空的停车格位置,以利驾驶找寻停车位。与现有系统相比,我们提出的系统因为摄影机的可视范围较大,所以只需要较少的摄影机数量;另外,因为我们提出的系统可自动分析停车格位置,因此其系统建置过程会便利许多。 在可行性及效率评估中,我们已对上述各方法及技术进行理论及实验分析,并得到良好之实验结果。 Omni-vision is an important and effective technique to make computers be aware of the surrounded environment. Different from traditional computer vision techniques, omni-vision ones emphasize more on capturing the environment information within a very wide area at one time without adding a motor control to the camera, moving the camera periodically, or using multiple cameras. Such techniques can avoid the difficulties of image stitching, camera hand-off, feature tracking over different cameras, etc. To achieve the capability of capturing information of a wide area, two special kinds of cameras are commonly used, which are catadioptric omni-directional cameras, and fisheye-lens cameras. The formal ones use a specially-designed reflective mirror to extend the viewing field, and the latter ones use a fisheye-lens to achieve the goal. However, since the environment information captured from a wide area is all compressed in a relatively small image, the captured image is inevitably heavily distorted, which makes the image analysis task much more difficult and complicated. Although, an easy and feasible way to deal with the heavy distortion is to unwarp the captured images to yield an image looking like one captured by a conventional perspective camera. However, since the resolution distributions captured by omni-directional cameras and by conventional perspective camera are quite different from each other, an unwrapped image becomes much more blurred in some regions, making image analysis tasks unstable and unreliable. Furthermore, the unwarping process needs some computation power, making it unsuitable to real-time applications and embedded systems with restricted computation power. To deal with the heavily-distorted images captured by omni-directional cameras, an accurate and reliable space line detection method without unwarping the distorted image is proposed. Also, to model the imaging process conducted by an omni-directional camera, a new camera model along with a convenient calibration process to calibrate an omni-camera easily is proposed. This new calibration technique requires only one straight line in the environment without knowing the position or direction of the line, making it possible for non-technical user to conduct the calibration work which is a big step toward consumer electronics. In addition, from the viewpoint of a consumer, the setup procedure of an omni-vision system should be sufficiently convenient for use by a typical user with no technical background. In this sense, a new binocular omni-vision system is proposed, which allows the user to place the two omni-directional cameras freely at any positions and with any orientations. After the two cameras are placed, the system can automatically derive the cameras’ positions and orientations via analysis of the space lines within the environment. As a result, the binocular omni-vision system can calculate 3D information correctly for use in many advanced human-machine interaction applications. Furthermore, for applications requiring precise 3D information, an optimization framework along with three different optimization algorithms are proposed as well to tell the user where to place the two omni-cameras, and what are the best orientations. With these optimization algorithms, the user can set up a binocular omni-vision system which acquires the most precise 3D data. Finally, the proposed omni-vision techniques are extended for uses in the application of indoor parking lot management. The proposed system for this application utilizes the omni-directional cameras mounted on the ceiling, and automatically analyzes the acquired images to obtain the locations of the parking spaces and detect vacant parking spaces. Different from existing similar application systems, the proposed one requires fewer cameras due to the wider fields of view of the cameras, and is much more convenient to set up because of the developed automatic parking-space analysis capability. The feasibility and effectiveness of all the above proposed methods and systems are demonstrated by theoretical analyses and good experimental results. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT079855864 http://hdl.handle.net/11536/73548 |
显示于类别: | Thesis |
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