基于粒子滤波器的摄像机运动参数估计

针对利用运动矢量估计摄像机运动参数的问题,将运动矢量作为状态,以块的位置作为状态索引,根据区域的局部相关性自适应地确定状态转移方程,以块匹配的平均绝对误差作为状态估计的观测输出,从而建立状态空间模型。基于该模型利用粒子滤波器估计运动矢量,采用重采样技术来消除粒子退化的现象,最后按照运动矢量与摄像机参数的关系模型,借助最小二乘法确定最优的摄像机参数。实验表明,该算法以较少的搜索点可以估计得到具有时空一致性的运动矢量场,进而能估计出反映摄像机真实运动的摄像机运动参数。     

流体运动估计光流算法研究综述

对流体图像序列进行运动分析一直是流体力学、医学和计算机视觉等领域的重要研究课题。从图像对中提取的密集精确的速度矢量场能够为许多领域提供有价值的信息,基于光流法的流体运动估计技术因其独特的优势成为一个有前途的方向。光流法可以获得具有较高分辨率的密集速度矢量场,在小尺度精细结构的测量上有所改进,弥补了基于相关分析法的粒子图像测速技术的不足。此外,光流方法还可以方便的引入各种物理约束,获得较为符合流体运动特性的运动估计结果。为了全面反映基于光流法的流体运动估计算法的研究进展,本文在广泛调研相关文献的基础上,对国内外具有代表性的论文进行了系统阐述。首先介绍了光流法的基本原理,然后将现有算法按照要解决的突出问题进行分类：结合流体力学知识的能量最小化函数,提高对光照变化的鲁棒性,大位移估计和消除异常值。对每类方法,从问题解决过程的角度予以介绍,分析了各类突出问题中现有算法的特点和局限性。最后,总结分析了流体运动估计技术当前面临的问题和挑战,并对未来基于光流法的运动估计算法的研究方向和研究重点进行了展望。     

Adaptive robust estimation of affine parameters from block motion vectors

In this paper, we propose an affine parameter estimation algorithm from block motion vectors for extracting accurate motion information with the assumption that the undergoing motion can be characterized by an affine model. The motion may be caused either by a moving camera or a moving object. The proposed method first extracts motion vectors from a sequence of images by using size-variable block matching and then processes them by adaptive robust estimation to estimate affine parameters. Typically, a robust estimation filters out outliers (velocity vectors that do not fit into the model) by fitting velocity vectors to a predefined model. To filter out potential outliers, our adaptive robust estimation defines a continuous weight function based on a Sigmoid function. During the estimation process, we tune the Sigmoid function gradually to its hard-limit as the errors between the model and input data are decreased, so that we can effectively separate non-outliers from outliers with the help of the finally tuned hard-limit form of the weight function. Experimental results show that the suggested approach is very effective in estimating affine parameters reliably.     

3D motion estimation of bubbles of gas in fluid glass,using an optical flow gradient technique extended to a third dimension

To solve the problem of estimating velocities of gas bubbles in melted glass, a method based on optical flow constraint (OFC) has been extended to the 3D case. A single camera, whose distance to the fluid is variable in time, is used to capture a sequence of frames at different depths. Since objects are not static, we cannot obtain two frames of different height values at the same time, and to our knowledge, this prevents the use of common 3D motion estimation techni ques. Since the information will be rather sparse, our estimation takes several measures around a given pixel and discards the erroneous ones, using a robust estimator. Along with the exposition of the practical application, the estimation proposed here is first contrasted in the 2D case to common benchmarks and then evaluated for a synthetic problem where velocities are known. Received: 9 July 2001 / Accepted: 5 August 2002 Published online: 3 June 2003 This work has been supported by Saint Gobain Cristaleria S.A., under contract FUO-EM-034-01 with Oviedo University, Spain.     

Experimental investigation of the effect of thermal comfort parameters on cervical range of motion

The most well-known ailment affecting the neck muscles is neck stiffness, caused by sharp changes in temperature, chilling of the muscles by air conditioning or drafts, and consequent painful muscle contractions. A stiff neck is typically characterized by soreness and difficulty in moving the neck – especially when trying to turn the head to the side. A stiff neck may also be accompanied by a headache, neck pain, shoulder pain and/or arm pain. Reduced cervical range of motion (ROM) is a common finding in people with neck pain. Musculoskeletal disorders continue to represent a major source of pain and discomfort as well as a significant source of workday loss and workers' compensation costs.In this study, the effects of parameters in air conditioning such as temperature, humidity and air velocity on cervical ROM have been investigated experimentally. In this investigation, each of the three parameters was used as a variable while the others were kept constant in a controlled laboratory room, and the effects of the parameter variations were investigated. Based on the observation that individuals often enter the air conditioned room perspiring in summer conditions, both dry and sweaty conditions were examined. Finally, experimental data were assessed with ANOVA analyses, and cervical rotation was found to be influenced by temperature and air velocity, but not humidity. It was also determined that parameters (temperature, air velocity and humidity) are not effective factors on cervical motion limitation provided that indoor air conditions remain within comfort limits which are prescribed in current standards of ASHRAE Standard 55 – 2004 and ISO 7730.     

On the observability of linear motion quantities in navigation systems

Navigation systems are a key element in a large variety of mobile platforms, where the correct knowledge of their position and attitude is essential in most applications. This paper focuses on the observability of linear motion quantities (position, linear velocity, linear acceleration, and accelerometer bias). It presents necessary and sufficient conditions, with a clear physical insight, for the observability of these variables in 3-D. The analysis provided is based on kinematic models, which are exact and intrinsic to the motion of a rigid-body, and different cases are presented depending on the assumptions made on the sensor suite that is available on-board.     

Solving camera parameters from the perspective projection of a parameterized curve

Given the two-dimensional perspective projection of a known conic or polygon of unknown size and position in three-dimensional space, we show how to determine the camera look angles relative to the plane where the curve lies. Separate cases are discussed for conic and polygons. We then show that this technique can be used to solve for any planar or nonplanar curves, as long as they can be represented in parametric forms.     

Unified optical flow field approach to motion analysis from a sequence of stereo images

In this paper a new approach to motion analysis from stereo image sequences using unified temporal and spatial optical flow field (UOFF) is reported. That is, based on a four-frame rectangular model and the associated six UOFF field quantities, a set of equations is derived from which both position and velocity can be determined. It does not require feature extraction and correspondence establishment, which are known to be difficult, and only partial solutions suitable for simplistic situations have been developed. Furthermore, it is capable of detecting multiple moving objects even when partial occlusion occurs, and is potentially suitable for nonrigid motion analysis. Unlike the current existing techniques for motion analysis from stereo imagery, the recovered motion by using this new approach is for a whole continuous field instead of only for some features. It is a purely optical flow approach. Two experiments are presented to demonstrate the feasibility of the approach.     

基于深度相机的手腕识别与掌心估测算法(HHME2013-ID51)

当手和手臂都进入深度相机所设定的有效深度范围时,它们将被作为一个整体来提取,若处理时也把它们作为一个整体,这可能会影响手势交互的一些重要算法,如掌心估测,手朝向估测,手的跟踪等。本文分析了手腕的运动特征和手的轮廓特点,并利用内切矩形的几何特征,提出了手腕识别算法来分割手与手臂;为了提高掌心估测算法的性能,本文分析了锐角三角形和最大内切圆的几何特征,并结合手势交互的特点,提出了新的掌心估测算法。经实验证明,手腕识别算法能较好地分割出手与手臂,新的掌心估测算法较之原算法在性能上有显著提高。     

计算机视觉的PNP问题的最优解

本文讨论了计算机视觉的PNP(Perspective-N-Point)问题:根据观察到的n个已知特征点的象点求解被观察物体相对于相机的三维运动参数.由于象噪声,该问题本质上是非线性最优化问题.本文导出一个闭式解,并提出若干克服象噪声影响的方法.仿真试验的结果表明本文的方法有很好的应用前景.     

基于深度相机的手腕识别与掌心估测

目的当手和手臂都进入深度相机所设定的有效深度范围时,它们将被作为一个整体来提取,若处理时也把它们作为一个整体,这可能会影响手势交互的一些重要算法,如掌心估测、手朝向估测、手的跟踪等。掌心是手势交互中较为稳定的点,掌心与手簇中心的连线常被用来估测手的朝向。因此提高掌心估测算法的性能有助于提高手势交互的整体性能。方法为了有效地分割手与手臂,从分析手腕的运动特征和手的轮廓特点入手,并利用内切矩形的几何特征,提出手腕识别算法;为了提高掌心估测的性能,从手势交互的特点入手,分析了锐角三角形和最大内切圆的几何特征,提出新的掌心估测算法。结果本文算法在空气多点触摸系统中进行了实验,新的掌心估测算法较之原算法在性能上提高了近7倍,且仍然能保持掌心坐标的稳定性,坐标偏差不大于3个像素。同时手腕识别算法的引入也提高了掌心估测的准确性。结论实验结果表明,手腕识别算法能较好地分割出手与手臂,新的掌心估测算法能很好地支持实时交互。     

公路汽车视觉导航中运动目标的检测与跟踪方法的研究

通过对室外行驶车辆上所采集的长序列图象的处理与分析,研究公路汽车计算机辅助礼堂导航中运动目标的检测与跟踪问题。算法的核心是根据图象中的水平、垂直边缘及目标尾部的局部对称性检测和图象中目标的存在,进而建立描述目标与摄象机之间的相对运动的状态模型和表示目标循征的透视投影模型,应用扩展的卡尔曼滤波器进行3维运动参数估计。     

Best performing parameters of linear and non-linear seismic base-isolator systems obtained by the power flow analysis

In this paper the problem of finding the best performing base isolator parameters of a seismic excited structure is treated. The structural and earthquake parameters and the isolator type are considered assigned. The approach here proposed is based on the minimization of the power flow transmitted by the isolator to the structure. The power flow is a statistical measure of the power transmitted to the structure during an earthquake. The earthquake is idealized as a filtered stochastic process. This approach considers the structure–isolator–excitation system as a super-structure in which the structure, the isolator and the excitation filter are the sub-structures. It guarantees a very good global behaviour of the structure, both in terms of relative displacements and in terms of accelerations. The isolator types considered in this work are the linear, the yielding and the friction ones.     

基于时空预测向量相关性的运动估计算法

针对UMHexagonS算法体现出来的问题,利用时间预测向量和空间预测向量的位置映射关系,提出了一种新的运动估计算法--基于时空预测向量相关性的运动估计算法。该算法首先在小范围得到最优点后,继续利用预测矢量的时空方向相关性进行特定方向的扩展搜索,避免了提前落入局部最优点,并减少了搜索点数,从而提高了搜索质量。实验结果表明,与UMHexagonS算法相比,该算法在保持码率基本不变的情况下,能有效地减少运动估计时间,并且能一定程度地提高单帧的峰值信噪比。关键词：     

Designing and testing a calibrating procedure for combining the coordination systems of a handling robot and a stationed video camera

The paper discusses some of the results of designing and testing a calibrating procedure with important implications in contemporary robotics. This procedure is also mentioned in the literature as the “procedure for calibrating by matching the coordination systems of a robot and a stationed video camera”. The procedure is tested by a training robotechnic system, which consists of an anthropomorphic robot with five stages of freedom and a stationed video camera that can identify solid stationary objects. The results of this experimental testing are used to create and adopt some new methods for laboratory exams in robotics for students of FA in a Technical University and for developing further research on calibrating procedures in robotics needed for the industry.     

Decomposition and composition of the properties of alternatives in multicriteria decision-making problems

It is shown that under the vector approach, the problem of making decisions by decomposing the properties of alternatives can be represented by a hierarchical system of criteria. At the lower hierarchy level, an alternative is evaluated for separate properties on the basis of a criterion vector and, at the upper level, a composition is used to evaluate the alternative as a whole. The problem is solved by the method of nested scalar convolutions of vector-valued criteria. Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 117–122, January–February 2009.     

Unmeasured temperature control in the presence of unknown drifting parameters in a cruise ship application

In cruise ship applications several waste heat recovery systems have been developed over the years in order to harvest the excess heat produced by the diesel engine and is stored in the coolant as thermal energy for instance. In this paper, a detailed model of a Fresh-Water-Cooling system is developed based on first principles and a given circuit scheme provided by the vessel manufacturer. The Fresh-Water-Cooling system consists of multiple interconnected subsystems; in this paper the main focus lies on the heat exchanger, where the waste heat recovery process takes place. Due to the presence of unmeasured states and uncertain model parameters the heat exchanger is modelled as partially measured stochastic system. Further the process is proved to be conditionally Gaussian, which makes the use of a conditionally Gaussian filter possible. It produces optimal estimates for the states and the unknown drifting parameters in the mean square sense. The process state is locally stabilized by the estimated process values using stabilizing feedback control.     

Finding the focus of expansion and estimating range using optical flow images and a matched filter

The focus of expansion plays an important role in many vision applications such as three-dimensional reconstruction, range estimation, time-to-impact computation, and obstacle avoidance. Most current techniques are based on correspondence or on accurate flow estimation and are therefore considered computationally heavy. This paper presents an efficient technique to find the focus of expansion from optical flow. The technique utilizes a specially designed matched filter that does not require an exact estimation of the optical flow but rather can use a low-quality estimation of it. In addition, based on the location of the focus of expansion and its immediate neighborhood, the paper suggests a way to estimate the range to the focus of expansion. Based on the experimental results, the technique has proved to be both accurate and efficient.Received: 26 January 2003, Accepted: 18 March 2004, Published online: 14 September 2004 Correspondence to: Didi Sazbon     

Sequential learning employing unfamiliar teacher hypothesis (SLEUTH) with concurrent estimation of both the parameters and teacher characteristics

Parametric learning in an unfamiliar environment, i.e., under unknown degree of supervision, forms the topic of this study. In addition to the learning of the distribution parameters, the learning scheme presented here has the novel capability of learning about the unfamiliar teacher, i.e., estimating the teacher characteristics inherent in the environment. This learning, under an unfamiliar teacher hypothesis, is seen to be computationally feasible and the results of simulation reveal the efficacy of the scheme in improving the learning under the unfamiliar teacher through learning about the teacher.