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在计算机视觉和图象处理中,单轴旋转运动被广泛地应用于基于图象的场景绘制,其中具有代表性的有同心拼图和立体全景图.在这些图象的绘制过程中,单轴旋转运动的旋转角度是一组关键的参数.旋转角度可以通过计算单轴旋转运动的不变量和对应点予以求解,然而在求解单轴旋转运动不变量的算法中,需要拟合场景中一个点的相对运动轨迹在图象平面形成的二次曲线.由于场景中点的在图象平面的可见轨迹所对应的旋转夹角较小,直接拟合非常困难.本文通过部分场景中存在的对应直线信息,给出了求解二次曲线的一个算法,并通过实验验证了算法的有效性. 相似文献
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本文讨论了存在小失真的图象边界为矩形的图象的校正问题,提出一种基于改进随机Hough变换的自动校正算法.该算法通过改变参数空间原点的位置使参数的取值范围缩小,既节约了存储空间又利于直线的提取.本文还将以梯度方向为像素点分类的方法引入到随机Hough变换中,大大提高了直线的提取精度,并改善了时间特性.该算法具有抗干扰能力强,运行时间短等优点,并且由于算法采用的是基于直线的提取方法,因此能较好的处理边界不连续的情况. 相似文献
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计算线流场的主要作用是作为中间介质来重建三维物体的运动和结构.本文提出了基于直线的线流场概念及其计算方法,其基本思路是首先使用霍夫变换提取图象系列中特征直线的坐标;然后通过建立相邻图象之间对应直线的匹配准则,找出对应直线,从而建立位移场;最后对位移场求时间导数得到直线的线流.图象中所有特征直线的坐标和线流的集合定义为直线的线流场.用L型多面体的综合图像进行了实验,实验表明本文所提出的线流场计算方法是可行的. 相似文献
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摄像机内参数自标定——理论与算法 总被引:3,自引:0,他引:3
讨论如何通过摄像机的旋转运动标定其内参数.当摄像机绕其坐标轴旋转时,运用
代数方法给出了计算内参数的公式.该公式在2D投影变换接近理论值P时是非常实用的.
在摄像机绕未知轴旋转时,根据相应的2D投影变换,运用矩阵特征向量理论给出了内参数的
通解公式.通过摄像机绕两个不同未知轴的旋转,摄像机内参数能被唯一地确定.这些结果为
摄像机自标定算法提供了理论基础,同时也给出了实用性算法.模拟实验和真实图像实验的
结果表明本文所给的算法具有一定实用价值. 相似文献
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线性确定无穷远平面的单应矩阵和摄象机自标定 总被引:10,自引:0,他引:10
引入了一种新的对无穷远平面的单应性矩阵(The infinite homography)的约束方程并
据此提出了一种新的摄象机线性自标定算法.与文献中已有的方法相比,该方法对摄象机的运
动要求不苛刻(如不要求摄象机的运动为正交运动),只须摄象机作一次平移运动和两次任意刚
体运动,就可线性唯一确定内参数.该方法主要优点在于:在确定无穷远平面的单应性矩阵的过
程中,不需要射影重构,也不需要有限远平面信息,唯一所需要的信息是图象极点,从而简化了
文献中现有的算法.另外同时给出了由极点确定(运动组)关于无穷远平面单应性矩阵的充分必
要条件.模拟实验和实际图象实验验证了该方法的正确性和可行性. 相似文献
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设计了一个扩展Robert算子,该算子能够在有噪声的情形下对图象中各种宽度的线条进行检测。当使用Hough变换确定直线的参数时,首先只用Hough变换检测第一条最为显著的直线,随后去掉该条直线及其附近的点,然后再次对图象进行Hough变换,并重复此过程,直到找到所有直线或者Hough变换后参数平面上的值都小于某个阈值为止。使用此改进后的Hough变换能够准确地检测到图象中构成网格的直线的参数。给出了具体的检测例子。 相似文献
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提出了一种基于多直线特征的全局运动估计算法,同时也介绍了它在电子图象稳定(EIS)系统中的应用,首先,用全局运动估计技术来估计摄像机的运动,即通过小波变换法提取图象中的边缘,并利用Hough变换法提取图象中的直线段特征,然后按照直线段的特征参数和位置选择原则选择具有分布特性的多个直线段,并通过对应的直线段特征比较计算局部运动参数和全局运动参数;最后根据全局运动估计结果,利用滤波法进行抖动判别和补偿,实现对图象序列的稳定处理,实验结果表明,多直线特征可以准确且稳定地估计摄像机的运动参数,通过滤波法可以消除视频序列的抖动。 相似文献
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现有的非刚体三维运动重建算法很难根据不同的场景、不同的非刚体来寻找不同的形状基,这种情况对重建
过程产生了很大的影响,造成模型失真。为了解决这一问题,提出一种基于Murkowski距离连续的非刚体三维运动
恢复算法,该算法根据在高速分解的图像序列中帧与帧之间的运动参数与特征点位移变化都呈现连续平缓的物理特
性,在Murkowski距离约束的情况下,将运动结构参数通过非线性优化的方法来进行求解,最终得到非刚体的三维运
动结构,并且通过仿真实验,验证了它的可行。 相似文献
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The iterative closest point (ICP) algorithm represents an efficient method to establish an initial set of possible correspondences between two overlapping range images. An inherent limitation of the algorithm is the introduction of false matches, a problem that has been tackled by a variety of schemes mainly based on local invariants described in a single coordinate frame. In this paper we propose using global rigid motion constraints to deal with false matches. Such constraints are derived from geometric properties of correspondence vectors bridging the points described in different coordinate frames before and after a rigid motion. In order to accurately and efficiently estimate the parameters of interest, the Monte Carlo resampling technique is used and motion parameter candidates are then synthesised by a median filter. The proposed algorithm is validated based on both synthetic data and real range images. Experimental results show that the proposed algorithm has advantages over existing registration methods concerning robustness, accuracy, and efficiency. 相似文献
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Language-based information ftow security is a promising approach for enforcement of strong security and protection of the data confidentiality for the end-to-end communications. Here, noninterference is the standard and most restricted security property that completely forbids confidential data from being released to public context. Although this baseline property has been extensively enforced in various cases, there are still many programs, which are considered secure enough, violating this property in some way. In order to control the information release in these programs, the predetermined ways should be specified by means of which confidential data can be released. These intentional releases, also called declassifications, are regulated by several more relaxed security properties than noninterference. The security properties for controlled declassification have been developed on different dimensions with declassification goals. However, the mechanisms used to enforce these properties are still unaccommodating, unspecific, and insufficiently studied. In this work, a new security property, the Relaxed Release with Reference Points (R3P), is presented to limit the information that can be declassified in a program. Moreover, a new mechanism using reachability analysis has been proposed for the pushdown system to enforce R3P on programs. In order to show R3P is competent for use, it has been proved that it complies with the well-known prudent principles of declassification, and in addition finds some restrictions on our security policy. The widespread usage, precision, efficiency, and the influencing factors of our enforcement have been evaluated. 相似文献
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欠驱动刚体航天器姿态运动规划的遗传算法 总被引:6,自引:1,他引:5
研究欠驱动刚体航天器姿态的非完整运动规划问题.航天器利用3个动量飞轮可以控制其姿态和任意定位,当其中一轮失效,航天器姿态通常表现为不可控.在系统角动量为零的情况下,系统的姿态控制问题可转化为无漂移系统的运动规划问题.基于优化控制理论,提出了求解欠驱动刚体航天器的姿态运动控制遗传算法,并且数值仿真表明:该方法对欠驱动航天器姿态运动的控制是有效的. 相似文献
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Janusz Jakubiak Krzysztof Tchoń Władysław Magiera 《International journal of control》2013,86(9):1965-1974
We address the motion planning problem in specific mechanical systems whose linear and angular velocities depend affinely on control. The configuration space of these systems encompasses the rotation group, and the motion planning involves the system orientation. Derivation of the motion planning algorithm for velocity affine systems has been inspired by the continuation method. Performance of this algorithm is illustrated with examples of the kinematics of a serial nonholonomic manipulator, the plate-ball kinematics and the attitude control of a rigid body. 相似文献
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刚体空间运动参数估计 总被引:5,自引:1,他引:4
本文发展了一种模型匹配估计算法,它具有较高的鲁棒性.根据已做的总数达一千二百万个不同空间点的实验显示:在采样总数N≤30时,只要有4到5对匹配正确的点就可以准确地估计出刚体空间运动的参数.这种高鲁棒性使得该方法能够用于多个刚体运动的分析. 相似文献
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The metric reconstruction of a non-rigid object viewed by a generic camera poses new challenges since current approaches for Structure from Motion assume the rigidity constraint of a shape as an essential condition. In this work, we focus on the estimation of the 3-D Euclidean shape and motion of a non-rigid shape observed by a perspective camera. In such case deformation and perspective effects are difficult to decouple – the parametrization of the 3-D non-rigid body may mistakenly account for the perspective distortion. Our method relies on the fact that it is often a reasonable assumption that some of the points on the object’s surface are deforming throughout the sequence while others remain rigid. Thus, relying on the rigidity constraints of a subset of rigid points, we estimate the perspective to metric upgrade transformation. First, we use an automatic segmentation algorithm to identify the set of rigid points. These are then used to estimate the internal camera calibration parameters and the overall rigid motion. Finally, we formulate the problem of non-rigid shape and motion estimation as a non-linear optimization where the objective function to be minimized is the image reprojection error. The prior information that some of the points in the object are rigid can also be added as a constraint to the non-linear minimization scheme in order to avoid ambiguous configurations. We perform experiments on different synthetic and real data sets which show that even when using a minimal set of rigid points and when varying the intrinsic camera parameters it is possible to obtain reliable metric information. 相似文献