融合道路图像关键信息的车距视觉测量方法

提出了一种融合道路图像关键信息的纵向车距视觉测量方法,在道路成像平面内建立了基于车道平面约束的视觉测距模型,运用边界约束Hough变换采集两侧道路标识线的斜率、聚点坐标以及车道宽度信息,自动求解视觉传感器的高度及俯仰角等测距参数。选取双通道Gabor滤波器提取目标车辆的5尺度8方向特征样本,联合AdaBoost分类器与级联Cascade筛选有效特征,快速精确提取目标特征点的坐标参数。实验结果表明,视觉测量值与实测值的绝对误差平均值为1.37 m,相对误差平均值为2.38%,测距平均耗时32 ms,与传统测距方法相比较,测量精度和实时性均得到了提高,适合于汽车主动防撞安全系统中应用。     

激光瞄靶训练系统中鱼眼图像的校正

讨论了激光瞄靶训练系统中鱼眼图像的校正问题.根据胸环靶图像各环宽度相等的特性,使用最小二乘法拟合图像上各点到镜头光心的距离和无畸变距离之间的映射关系,实现了靶心与光心重合情况下鱼眼图像的校正和成绩判定方法.在靶心与光心非重合情况下,通过连接靶心与光心所在的直线,求出该直线与各环交点到光心的距离和无畸变距离,拟合新的映射关系.实验结果表明,校正后判定射击成绩精度达到0.1环.     

基于数据特征的多传感器融合实时目标检测

为了进一步降低目标检测出现的误检率,提出了一种基于传感器数据特征的融合目标检测算法。首先,为了减少部分离群噪声点对点云表达准确性的影响,采用统计滤波器对激光雷达原始点云进行滤波处理;其次,为了解决点云地面分割在坡度变化时,固定阈值会导致分割不理想的问题,提出了自适应坡度阈值的地面分割算法;然后,建立KD（k-dimensional）树索引,加速DBSCAN（density-based spatial clustering of applications with noise）点云聚类,基于Andrew最小凸包算法,拟合最小边界矩形,生成目标三维边界框,完成聚类后的目标点云位姿估计;最后,将激光雷达检测到的三维目标点云投影到图像上,投影边界框与图像检测的目标边界框通过IoU关联匹配,提出基于决策级的三维激光雷达与视觉图像信息融合算法。使用KITTI数据集进行的测试实验表明,提出的点云聚类平均耗时降低至173 ms,相比传统的欧氏距离聚类,准确性提升6%。搭建硬件实验平台,基于实测数据的实验结果表明,提出的融合算法在目标误检率上比YOLO v4网络降低了约10%。     

基于线结构光视觉的燃料组件变形测量技术研究

针对快堆燃料组件外形变形参数的测量,设计了基于线结构光的燃料组件变形测量系统,并考虑到辐射对电子元器件和测量精度的影响,进行了测量系统的辐射屏蔽设计。对辐射屏蔽玻璃的折射对测量的影响进行了研究,并在空气中线结构光测量模型的基础上提出一种折射校正的线结构光测量模型。在空气中进行测量系统标定,然后对加玻璃的测量值进行折射校正,通过多组测量实验表明折射校正模型校正误差为±0.05 mm,线结构光燃料组件测量系统的全局参数测量的标准差不大于0.03 mm。组件测量系统能在一定辐照剂量下能实现燃料组件变形参数的高精度测量,对于获取燃料组件物理参数和堆芯设计具有重要的意义。     

地铁隧道沉降变形实时监测系统误差分析

根据图像传感器网络的沉降变形监测原理,建立地铁隧道沉降变形监测系统的数学模型。利用误差分析理论对系统测量误差进行分析,提出沉降变形监测系统的误差累积计算模型。给出在满足1 km的测量距离上获得±3 mm的测量精度条件下,图像传感器应满足的精度要求。分析该监测系统控制累积误差随监测点数增多而扩大的有效性,为提高监测系统的精度提供理论依据。     

雷达引导的视频联动监控模型及算法

针对视频安防监控系统中出现的监视区域有限、目标定位困难等问题,利用雷达监测范围广、不受光学条件影响的特性,建立了雷达引导的视频联动监控模型,并在此基础上提出了目标定位算法和多目标选择算法。首先,根据雷达检测到的目标信息,自动计算出运动目标在系统联动模型中对应的摄像机方位角和俯仰角,从而引导摄像机准确锁定目标并实时监控追踪。然后,当监控场景中出现多个目标时,采用多目标选择算法,将目标的离散程度、径向速度及其与摄像机之间的距离进行数据加权融合,选择出优先级别最高的目标进行重点监控。实验结果表明,所提目标定位算法对于行人与车辆的定位准确率分别达到0.94和0.84,能够实现目标的准确定位,多目标选择算法可在复杂环境中有效选择出最佳监控目标,具有良好的鲁棒性和实时性。     

Optotrak系统在风洞模型变形与姿态测量中的应用研究

风洞试验中模型的变形量与空间姿态角是非常重要的参数,变形量可用于CFD修正,而模型姿态角的准确度直接影响到试验数据的质量和特性.为了准确获取这些参数,介绍了一种基于三线阵CCD交汇原理的光学测量设备——Optotrak系统,以及应用该系统开展的测量试验技术.通过在沿翼展方向的多个剖面上安装Marker点,获取模型在不同...     

一种基于几何性质的鱼眼图像校正算法

为快速、高效地校正具有径向畸变的鱼眼图像,提出一种基于几何性质的校正算法。根据投影不变性原理以及径向畸变的几何特性,计算畸变直线的斜率,并通过求解线性方程组得出多项式校正模型的参数。实验结果表明,该算法能够以较低的运算复杂度获得较高的校正精度,相比于采用数学迭代拟合直线的方法,该算法在图像整体校正质量上有明显改善。     

近地炸点声定位算法研究

针对四元十字阵被动声定位算法存在定位精度受目标方位角影响的问题,提出基于时间差技术的五元十字阵算法;研究了五元十字阵阵元间的几何关系与参数的计算,利用球面坐标法及最小二乘法推导了目标定位计算式,进行了系统误差分析;实验结果表明,该算法提高了炸点的测距与测向精度,改善了目标方位角对弹丸炸点的定位精度的影响;与四元十字阵算法相比,五元十字阵算法在距离、方位角和俯仰角的误差分别是1.33m、0.0003°和0.44°。     

双目立体视觉系统的精度分析

为提高双目立体视觉系统的测量精度,分析双目视觉系统的工作原理以及该系统各个环节的误差模型.通过提高标定模板的精度、增加标定图像,可以减小标定误差及图像校正行对齐误差.分析图像识别误差对视觉系统测量精度的影响,导入视觉系统的结构参数与测量误差之间的关系,从而确定结构参数对测量精度的作用.讨论物距对测量精度的影响,并给出合...     

南水北调中线工程渠堤变形安全监控指标研究

为研究大型调水工程中渠堤的变形安全,在分析南水北调中线工程典型渠段变形影响因素的基础上,对水压、时效、降雨等因素进行研究,建立相应的渠坡位移统计模型,对边坡实测变形数据进行回归分析,验证统计模型的合理性,采用典型监测效应量的小概率法拟定渠道边坡内部的水平位移等相应测点的变形监控指标。结果显示,拟合值与实际值符合良好,可以作为渠堤的监控指标,为渠堤变形安全监控指标的发展奠定基础。     

Correcting for the influence of frozen lakes in satellite microwave radiometer observations through application of a microwave emission model

The spatial resolution of passive microwave observations from space is of the order of tens of kilometers with currently available instruments, such as the Special Sensor Microwave/Imager (SSM/I) and Advanced Microwave Scanning Radiometer (AMSR-E). The large field of view of these instruments dictates that the observed brightness temperature can originate from heterogeneous land cover, with different vegetation and surface properties.In this study, we assess the influence of freshwater lakes on the observed brightness temperature of AMSR-E in winter conditions. The study focuses on the geographic region of Finland, where lakes account for 10% of the total terrestrial area. We present a method to mitigate for the influence of lakes through forward modeling of snow covered lakes, as a part of a microwave emission simulation scheme of space-borne observations. We apply a forward model to predict brightness temperatures of snow covered sceneries over several winter seasons, using available data on snow cover, vegetation and lake ice cover to set the forward model input parameters. Comparison of model estimates with space-borne observations shows that the modeling accuracy improves in the majority of examined cases when lakes are accounted for, with respect to the case where lakes are not included in the simulation. Moreover, we present a method for applying the correction to the retrieval of Snow Water Equivalent (SWE) in lake-rich areas, using a numerical inversion method of the forward model. In a comparison to available independent validation data on SWE, also the retrieval accuracy is seen to improve when applying the influence of snow covered lakes in the emission model.     

Review of: “Glaciers-Ocean-Atmosphere Interactions”. Edited by V. M. KOTLYAKOV,A. USHAKOV and A. GLAZOVSKY,Proceedings of the International Symposium,St Petersburg, 24-29 September 1990 (Wallingford,UK: IAHS Press, 1991.) [Pp. 549.] Price US$60.

Data gathered during the NASA sponsored Multisensor Aircraft Campaign Hydrology (MACHYDRO) experiment in central Pennsylvania (U.S.A.) in July, 1990 have been analysed to study the combined use of active and passive microwave sensors for estimating soil moisture from vegetated areas. These data sets were obtained during an eleven-day period with NASA's Airborne Synthetic Aperture Radar (AIRSAR), and Push-Broom Microwave Radiometer (PBMR) over an instrumented watershed, which included agricultural fields with a number of different crop covers. Simultaneous ground truth measurements were also made in order to characterize the state of vegetation and soil moisture under a variety of meteorological conditions. Various multi-sensor techniques are currently under investigation to improve the accuracy of remote sensing estimates of the soil moisture in the presence of vegetation and surface roughness conditions using these data sets. One such algorithm involving combination of active and passive microwave sensors is presented here, and is applied to representative corn fields in the Mahantango watershed that was the focus of study during the MACHYDRO experiment. In this algorithm, a simple emission model is inverted to obtain Fresnel reflectivity in terms of ground and vegetation parameters. Since Fresnel reflectivity depends on soil dielectric constant, soil moisture is determined from reflectivity using dielectric-soil moisture relations. The algorithm requires brightness temperature, vegetation and ground parameters as the input parameters. The former is measured by a passive microwave technique and the later two are estimated by using active microwave techniques. The soil moisture estimates obtained by this combined use of active and passive microwave remote sensing techniques, show an excellent agreement with the in situ soil moisture measurements made during the MACHYDRO experiment.     

基于位置修正机制和模型更新策略的跟踪算法

为了实现目标跟踪算法在无人机应用中的高实时性和高成功率,针对目标遮挡和目标形变量大导致的跟踪丢失问题,提出了一种基于相关滤波的改进算法,算法包含自适应位置修正机制和模型更新策略.该算法提取目标区域的方向梯度直方图特征(HOG)训练滤波器,预测下一帧的目标位置.当预测位置不满足高置信度条件时,融合颜色命名特征(CN)对位置进行修正.为了提高算法的运行效率,对融合后的特征进行主成分分析(PCA)降维处理.利用平均峰值相关能量、多峰检测及最大响应值进行模型更新.实验中将改进算法与近年来的优秀算法进行对比.结果表明,所提算法在目标被遮挡和形变量大的场景中,跟踪精度更高.     

一种基于斜率的摄像机畸变校正方法

普通 CCD摄像机在成像时都存在畸变成像误差 ,在机器人视觉检测及自动装配中 ,有效地进行误差校正对准确确定物体的位置具有重要的意义 .本文采用带有一阶径向畸变的小孔摄像机模型 ,提出一种基于线段斜率的方法 ,对摄像机镜头的径向畸变进行校正 ,不必标定太多的摄像机的外参数 ,方法简洁 ,适合于视觉系统中对摄像机畸变的实时校正 ,或对摄像机捕获的图像进行几何校正 .实验表明 ,具有很强的鲁棒性和较高的校正精度     

基于PSD的大坝变形监测仪关键技术研究

为解决现有大坝变形监测仪器可靠性不高等问题,基于半导体位置传感器PSD,以静力水准仪为例,在优化设计电路的基础上,设计新型变形监测仪器系统。通过系统一致性、稳定性和温度适应性实验,分析监测仪器的测量精度、温度适应性和测量时间3个关键技术指标:测量精度高达0.002 mm,温度稳定性达到0.001 mm,测量时间短到1 s。实验证明,PSD式新型监测仪器优于现有的变形监测仪器。     

基于高精度曲面建模的物体表面形变监测

道路、隧道、桥梁等物体表面形变监测是质量安全保障的重要前提。针对其表面监测问题，提出一种基于激光栅格化采样和高精度曲面建模的物体表面监测方法。该方法对监测物体表面利用栅格化采样进行高精度曲面建模和插值，通过多项式空间插值估计监测点的真实值和曲面第一、二基本量，对物体表面沉降和曲率半径参数变化角度进行监测。为验证该方法的有效性，在两组不同复杂程度的已知曲面上随机选取100个测试点，针对采样密度和插值密度分别进行数值仿真实验，并利用实物模型构建模拟形变实验，进而对测试点处的沉降变化和曲率半径变化进行监测。实验结果表明：在仿真实验中，高栅格化采样密度和插值密度能够大幅提高曲面重构精度，并降低物体表面不同复杂程度对监测精度的影响；在实物模拟形变实验中，沉降测量精度可达98.41%，曲率半径变化检测精度可达81.82%。     

An approach using random forest intelligent algorithm to construct a monitoring model for dam safety

The mechanism of dam safety monitoring model is analyzed; for the dam system comprehensive affected by multi-factor, the mapping relationship between the influence factors and the dam behavior effects domain is usually nonlinear. Synthesizing each kind of factor, 27 parameters are chosen as the main factors which affect the accuracy of the monitoring model. Taking the actual monitoring data as the evaluation factor, the dam safety monitoring model based on the random forest (RF) intelligent algorithm was built with the actual monitoring data to predict uplift pressure. At the same time, test the significance of each variable based on the RF monitoring model and calculate the importance degree of each variable for the model through the importance function. It is indicated that RF model can be relatively fast and accurately predict the uplift pressure of the dam according to the influence factors. The average prediction accuracy is more than 95%. As compared with other intelligent algorithms such as support vector machine, RF has better robustness, higher prediction accuracy, and faster convergence speed. Because of the uniformity of the calculation procedure and the universality of the prediction method, the RF model also has reasonable extrapolation for other dam safety monitoring models (such as crack opening and seepage discharge). Significance test results obtained by the two methods have shown that the impact of reservoir water level and daily rainfall on the uplift pressure is significant, and other factors’ impact on dam deformation is unstable and changes with the external environmental influence.

     

星载毫米波辐射计地面定标实验

对CE-1(嫦娥一号)卫星有效载荷微波探测仪初样样机8 mm微波辐射计进行了地面定标实验。测量了接收机的线性度和灵敏度;建立了射频前端微波辐射传输模型;应用该模型并结合测试结果,建立了失配条件下辐射计天线温度的定标方程。实验结果表明,接收机线性度为0.9999,灵敏度为0.17 K,定标误差小于0.85 K。为CE-1正样样机的研制以及科学目标的实现提供了定标参考。     

基于立体视觉的高精度标定与测量方法

立体视觉测量系统中,光学系统产生的畸变使目标的成像偏离了理论成像点,导致系统产生测量误差。针对提高系统测量精度的问题,提出一种基于立体视觉的测量方法。首先,根据标定板上各角点的像素分辨率,拟合整个成像平面的四次多项式,且多项式的系数与物体到相机的距离成比例;然后,应用双目测距原理,测量被测物体的纵向距离;最后,基于所得的多项式,应用单目相机测量待测物体的横向尺寸。实验结果表明,对于所提方法,当物体距离相机5 m以内时,其纵向距离误差可以减小到5%以内;当物体距离相机1 m时,其横向宽度测量误差在0.5 mm内,逼近理论最高分辨率。