CASIA OpenIR  > 毕业生  > 博士学位论文
视觉测量与定位问题研究
其他题名Study on Visual Metrology and Pose Determination
曾慧
学位类型工学博士
导师胡占义
2007-05-26
学位授予单位中国科学院研究生院
学位授予地点中国科学院自动化研究所
学位专业模式识别与智能系统
关键词视觉测量 单应矩阵估计 车轮与地面接触点 人脸姿态估计 机器人定位 Visual Metrology Homography Estimation The Contacting Point Of Wheel To The Ground Face Pose Estimation Robot Localization
摘要视觉测量与定位问题是计算机视觉领域的核心问题,具有重要的理论研究价值和广泛的应用前景。到目前为止,尽管国内外在此领域取得了丰硕的研究成果,但在实际应用过程中仍存在很多问题有待解决。因此,本文以视觉系统的实际需求为出发点,对具体应用过程中遇到的一些视觉测量与定位方面的问题进行了研究和探索,所完成的主要工作有: 1)针对直接线性方法在基于线对应的单应矩阵估计中在某些特殊的摄像机姿态下会出现较大误差的情况,提出了一种基于线对应的归一化单应矩阵估计方法并将其应用到视觉测量中。该方法不仅提高了算法的鲁棒性,同时又保持了直接线性方法简单、快速、易实现等优点。 2)利用车轮与地面的接触点必位于过车轮中心的像点和垂直消影点的直线上这一性质,提出了一种单幅图像、单个车轮情况下车轮与地面接触点的自动检测方法。大量图像的实验结果均验证了该方法的有效性,并成功应用于交通事故现场处理原型系统中。 3)研究了一种利用平面单应矩阵来估计人脸姿态及人脸在图像中位置的方法。该方法实施简单、不需要对摄像机内参数预先进行标定,能够在较大范围内比较精确地估计人脸姿态及人脸在图像中的位置。 4)给出了两种基于平面激光测量的移动机器人自定位方法。第一种方法是改进的Hough密度谱的方法,它的主要优点是避免了现有方法Hough变换离散化过程中的信息损失问题,提高了算法的精度和鲁棒性。第二种方法是基于Fourier-Mellin 变换的方法,主要利用Fourier变换的位移理论和Fourier-Mellin不变量来估计运动参数。为了避免图像离散化造成的信息损失,在该方法中使用基于Hausdorff距离的最近点迭代(ICP)算法来进一步精化平移向量。
其他摘要The most important issues in computer vision are visual metrology and pose determination. Although fruitful achievements have been obtained in the field, there still exist many difficult problems to hamper the real progress of applications. This thesis is focused on some real problems about visual metrology and pose determination. The main work can be summarized as:1)It is a conventional belief that line-based approaches perform better than point-based ones for homography estimation, as the line-fitting is generally more noise resistant than point detection. In this work, we show that blithely using line-based estimation is a risky business. More specifically, we show that when the image line(s) is (are) passing through or close to the origin, the line-based homography estimation could become wildly unstable whereas the point-based estimation performs normally. To tackle this problem, a new normalized method specially designed for line-based homography estimation is proposed and validated by extensive experiments.2)An automatic approach for detecting the contacting point of wheel to the ground is proposed. The fundamental principle of this approach is the fact that the contacting point must lie on the line going through the projection of the wheel center and the vertical vanishing point. Extensive experimental results show that the proposed approach is capable of detecting the contacting point satisfactorily and effectively.3)A simple and efficient method based on planar homography is proposed for face pose estimation. The method is composed of the following steps: At first, the parameters of the 3D planar face model are estimated from a single fronto-parallel face image. Then the homography between the face model plane and the image plane is estimated, by which the face pose and the face image location are determined. Finally, the M-Estimator is employed to further refine the results. The main characteristic of the proposed method is that it is simple to implement, does not need to calibrate the projective camera beforehand and can recover the face pose and the face image location satisfactorily under a wide degree of head motion.4)Two novel robot self-localization methods based on planar laser measurement are proposed. The first one is an improved Hough density spectrum based method, where a novel Hough density spectrum is introduced, and by which the location accuracy and robustness are both enhanced. The second one is a Fourier-Mellin transform based method. In this method, by firstly converting the two measurement point sets into two binary images, the Fourier-Mellin based image registration technique, a popular method in image registration field, is employed to determine the rotation parameter at first, then followed by a standard ICP technique with the Hausdorff distance as its cost for the estimation of the two translation parameters. The experimental results show that both our proposed methods can perform robustly and accurately.
馆藏号XWLW1060
其他标识符200418014628014
语种中文
文献类型学位论文
条目标识符http://ir.ia.ac.cn/handle/173211/5975
专题毕业生_博士学位论文
推荐引用方式
GB/T 7714
曾慧. 视觉测量与定位问题研究[D]. 中国科学院自动化研究所. 中国科学院研究生院,2007.
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