共查询到19条相似文献,搜索用时 203 毫秒
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针对战机对地侦查视频图像中地面旋转运动背景下运动目标检测高虚警、低实时性的问题,提出了一种基于改进光流法的旋转运动背景下对地运动目标实时检测算法。首先提取图像的特征点,在特征点处计算光流运动矢量,并通过光流矢量场估算背景运动矢量。根据战机飞行高度自适应计算目标像素尺寸,网格化分块待检测图像;然后将各个特征点光流矢量与背景运动矢量相比较,获得备选目标特征点。最后统计分块备选目标特征点密度,判断目标位置区域。对2组实验视频中央360像素×432像素区域进行目标检测实验,结果表明该算法能够准确地检测出地面运动目标,虚警率低。平均每帧检测耗时分别为29.460 ms和31.505 ms,满足战机对地运动目标检测的实时性。 相似文献
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针对直角坐标系中光流跟踪算法无法跟踪存在旋转和尺度变化目标图像的问题,在分析Horn-Schunck经典光流计算公式基础上,提出了一种对数极坐标域的梯度跟踪算法。该算法可以对存在旋转和尺度变化的运动目标实施跟踪,通过实验证明了这种方法在处理运动图像变化时是有效的。因而,这种用对数极坐标域的跟踪算法有一定的实用价值。 相似文献
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为了解决雷达目标跟踪的非线性估计问题,提出了一种基于最优线性无偏估计的交互式多模型(IMM)机动目标跟踪算法.该算法采用最优线性无偏估计(BLUE),把目标的状态在笛卡尔坐标来表示,而把雷达测量误差保留在极坐标下,并结合交互式多模型算法,实现对机动目标的有效跟踪.仿真实验验证了该算法的准确性和有效性. 相似文献
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杨叶梅 《计算机与数字工程》2011,39(9):108-110,160
该文为了实现对运动目标的检测,重点研究了基于梯度的Horn&Schunck光流算法,然后提出一种高斯金字塔的改进光流法,并结合最大类间方差的图像分割法和形态学滤波中的开、闭运算,完成运动区域的提取。实验仿真结果和数据表明改进的光流算法能准确获取运动目标区域,并更加省时。 相似文献
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Previous studies have shown that the Cartesian coordinate extended Kalman filter exhibits unstable behavior characteristics when utilized for bearings-only target motion analysis (TMA). In contrast, formulating the TMA estimation problem in modified polar (MP) coordinates leads to an extended Kalman filter which is both stable and asymptotically unbiased. Exact state equations for the MP filter are derived without imposing any restrictions on own-ship motion; thus, prediction accuracy inherent in the traditional Cartesian formulation is completely preserved. In addition, these equations reveal that MP coordinates are well-suited for bearings-only TMA because they automatically decouple observable and unobservable components of the estimated state vector. Such decoupling is shown to prevent covariance matrix ill-conditioning, which is the primary cause of filter instability. Further investigation also confirms that the MP state estimates are asymptotically unbiased. Realistic simulation data are presented to support these findings and to compare algorithm performance with respect to the Cramer-Rao lower bound (ideal) as well as the Cartesian and pseudolinear filters. 相似文献
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Mitiche A Sekkati H 《IEEE transactions on pattern analysis and machine intelligence》2006,28(11):1818-1829
This study investigates a variational, active curve evolution method for dense three-dimensional (3D) segmentation and interpretation of optical flow in an image sequence of a scene containing moving rigid objects viewed by a possibly moving camera. This method jointly performs 3D motion segmentation, 3D interpretation (recovery of 3D structure and motion), and optical flow estimation. The objective functional contains two data terms for each segmentation region, one based on the motion-only equation which relates the essential parameters of 3D rigid body motion to optical flow, and the other on the Horn and Schunck optical flow constraint. It also contains two regularization terms for each region, one for optical flow, the other for the region boundary. The necessary conditions for a minimum of the functional result in concurrent 3D-motion segmentation, by active curve evolution via level sets, and linear estimation of each region essential parameters and optical flow. Subsequently, the screw of 3D motion and regularized relative depth are recovered analytically for each region from the estimated essential parameters and optical flow. Examples are provided which verify the method and its implementation 相似文献
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《Computer Vision and Image Understanding》2007,105(1):86-92
Scale space is a natural way to handle multi-scale problems. Yang and Ma have considered the correspondence between scales, and proposed optical flow in the scale space. In this paper, we generalized Yang and Ma’s work to generic images. We first generalize the Horn–Schunck algorithm to multi-dimensional multi-channel image sequence. Since the global smoothness constraint for regularization is no longer suitable in general cases, we introduce localized smoothness regularization. In scale space optical flow, points in original image trends to aggregate at a large scale, so we introduce aggregation density as an additional smoothness coefficient. At last, we apply the proposed methods to color images and 3D images. 相似文献
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基于直线光流场的三维运动和结构重建 总被引:2,自引:0,他引:2
利用直线间运动对应关系,将像素点光流的概念和定义方法应用于直线,提出了直线光流的概念,建立了求解空间物体运动参数的线性方程组,利用三幅图像21条直线的光流场,可以求得物体运动的12个参数以及空间直线坐标.但是在实际应用当中,要找出这21条直线的光流场是很困难的,因此该文提出了运用解非线性方程组的方法,只需要6条直线的光流.就可以分步求出物体的12个运动参数,并根据求得的12个运动参数和一致的图像坐标系中的直线坐标,求得空间直线的坐标,从而实现了三维场景的重建. 相似文献
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The modification by H.H. Nagel (1987) of the approach developed by B.K.P. Horn and B.G. Schunck (1981) for determining optical flow is generalized to the case where local motion information is given by more than one constraint equation. Applying this scheme to three constraint equations reported in the literature, as a special case, a generalization of Nagel's approach is obtained. An existence and uniqueness result of solutions under very general conditions that, in turn, ensures the applicability of standard techniques to compute an approximate solution is presented 相似文献
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A new methodology, called hybrid predictive dynamics (HPD), is introduced in this work to simulate human motion. HPD is defined as an optimization-based motion prediction approach in which the joint angle control points are unknowns in the equations of motion. Some of these control points are bounded by the experimental data. The joint torque and ground reaction forces are calculated by an inverse algorithm in the optimization procedure. Therefore, the proposed method is able to incorporate motion capture data into the formulation to predict natural and subject-specific human motions. Hybrid predictive dynamics includes three procedures, and each is a sub-optimization problem. First, the motion capture data are transferred from Cartesian space into joint space by using optimization-based inverse kinematics (IK) methodology. Secondly, joint profiles obtained from IK are interpolated by B-spline control points by using an error-minimization algorithm. Third, boundaries are built on the control points to represent specific joint profiles from experiments, and these boundaries are used to guide the predicted human motion. To predict more accurate motion, the boundaries can also be built on the kinetic variables if the experimental data are available. The efficiency of the method is demonstrated by simulating a box-lifting motion. The proposed method takes advantage of both prediction and tracking capabilities simultaneously, so that HPD has more applications in human motion prediction, especially towards clinical applications. 相似文献
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A Quantitative Analysis of Current Practices in Optical Flow Estimation and the Principles Behind Them 总被引:1,自引:0,他引:1
Deqing Sun Stefan Roth Michael J. Black 《International Journal of Computer Vision》2014,106(2):115-137
The accuracy of optical flow estimation algorithms has been improving steadily as evidenced by results on the Middlebury optical flow benchmark. The typical formulation, however, has changed little since the work of Horn and Schunck. We attempt to uncover what has made recent advances possible through a thorough analysis of how the objective function, the optimization method, and modern implementation practices influence accuracy. We discover that “classical” flow formulations perform surprisingly well when combined with modern optimization and implementation techniques. One key implementation detail is the median filtering of intermediate flow fields during optimization. While this improves the robustness of classical methods it actually leads to higher energy solutions, meaning that these methods are not optimizing the original objective function. To understand the principles behind this phenomenon, we derive a new objective function that formalizes the median filtering heuristic. This objective function includes a non-local smoothness term that robustly integrates flow estimates over large spatial neighborhoods. By modifying this new term to include information about flow and image boundaries we develop a method that can better preserve motion details. To take advantage of the trend towards video in wide-screen format, we further introduce an asymmetric pyramid downsampling scheme that enables the estimation of longer range horizontal motions. The methods are evaluated on the Middlebury, MPI Sintel, and KITTI datasets using the same parameter settings. 相似文献