基于GPS数据的OMIS图像航线校正研究

随着GPS实时定位技术的发展,GPS广泛地应用于舰船、飞机等动态目标的导航定位。机载GPS数据用于遥感图像航线校正就是利用机载GPS数据模拟计算出飞机飞行的各种姿态参数,从而对由机载成像光谱仪获得的遥感图像进行方位校正,使遥感图像达到几何粗校正的结果,为几何精校正打下基础。OMIS是中国科学院上海技术物理所新近研制的128通道成像光谱仪,并于1998年8月在江苏常州进行了试验飞行。结合这次实验,利用机载GPS数据对飞行图像进行了航线校正研究,并结合实际飞行数据进行了实验,获得了较好的结果。     

轻型飞机成像光谱图象几何校正技术研究

成像光谱测量技术是近年来遥感领域的发展前沿之一，该技术以高光谱分辩率、高空间分辩率、高时相分辨率及普像合一为主要特征，在国民经济各个领域得到广泛应用。在剖析轻型飞机成像光谱测量系统成像环境特征的基础上，深入研究了低空遥感图象几何学理论，并利用数学模型分析方法，建立了航空成像光谱图象几何畸变模式及几何校正模型；提出了适合本系统的几何处理流程。利用所建立的几何校正模型和软件，对机载可见光/短波红外成像光谱数据进行了几何特性分析及几何校正，取得较好的图象处理效果，并证实了系统的实用性。     

天宫二号卫星宽波段成像光谱仪地理定位方法

本文针对天宫二号(Tiangong No.2,TG-2)宽波段成像光谱仪的宽波段相机进行观测几何和地理定位解算。TG-2搭载的宽波段成像光谱仪是用于海洋、气象和环境空间综合观测的新一代试验遥感仪器。解算该仪器观测几何和高质量遥感地理定位数据是开展上述应用的前提和基础。本文基于宽波段相机多CCD拼接直视推扫模式,根据其特殊的扫描几何和卫星空间位置姿态,建立仪器焦平面与地理空间位置的对应模型。通过大量实际观测的定位数据建立旋转角度与变形数量的关系,修正安装矩阵,提高了模型定位精度。利用该模型实现了对TG-2卫星宽波段成像光谱仪图像的地理定位。利用图像的地理位置进行投影,与高精度海陆模板进行比较,定位精度约为2个像元(200m)。     

高分辨率卫星影像几何校正研究

该文首先对遥感影像的变形机理与几何校正方法进行研究讨论,论述了多项式模型和有理函数模型等遥感图像几何校正模型,介绍了双三次卷积内插方法、最临近内插方法、双线性内插法等数字图像重采样方法,同时论述了地面控制点(GCP)及检查点的选取方法。在此基础上论述了遥感图像几何校正的一般步骤:根据现有数据特点,利用ERDAS对影像数据进行几何校正。最后对校正精度进行分析,结果符合预期要求,说明实验中所采取的方法与流程具有较高可靠性。     

一种基于RBF神经网络的遥感图像校正方法

研究基于RBF神经网络的算法针对遥感图像的几何校正,给出一个简单快速的实现方案,通过对实际图像进行了校正实验,获得满意的校正结果,说明谊方法能有效地精确校正图像的几何畸变.     

机载聚束SAR图像定位精度研究

根据机载聚束SAR成像几何关系及线性RD成像算法,对SAR图像的定位精度 进行了深入探讨。由于现有的惯性导航系统大多精度不高,并不能准确提供载机的真实运动 信息,利用这些参数进行成像处理会使目标偏离真实位置。本文主要分析惯性导航系统提供 的载机飞行参数对机载SAR定位精度的影响,建立定位方程并推导出定位误差解析公式。最 后对机载SAR图像定位精度进行仿真分析与实测数据处理验证,处理结果表明载机的视线方 向的速度误差和载机的位置误差是影响SAR图像定位精度主要因素。     

机载成像光谱图象边缘辐射畸变校正

由于受大气效应、地物反射非朗伯特性、仪器－太阳－目标相对几何关系以及仪器系统本身特性等多种因素的影响,机载成像光谱数据中不可避免地将引入系统或非系统的辐射畸变,严重地影响了数据表达信息的可靠性和有效性。目前虽然已有一些机载遥感图像辐射畸变校正方法,但由于受各种应用条件的限制,所发展的这些方法普遍缺乏实用性和通用性。该文在对机载成像光谱图象边缘辐射畸变形机制进行理论分析和探讨的基础上,针对机载成像光     

利用地面景象信息辅助的无人机自主定位技术

针对无人机自主定位过程中GPS定位系统失效的问题,提出了一种利用地面景象信息辅助的无人机自主定位技术,首先利用无人机所拍摄的实时航拍图像,与预先储存在无人机计算机中地面景象的数字化地形图进行匹配,从匹配结果中提取一个同名像点,结合地面景象数字化地形图所提供的数据信息获取此同名像点的地理位置坐标,根据同名像点位置与无人机位置间的几何关系,结合机载光电测量系统的坐标转换过程,实现无人机的自主定位过程。利用已知的地面同名像点的地理位置信息,反推出无人机的地理位置信息具有一定的创新性。由于整个定位过程存在实际误差,因此利用无人机飞行时记录的数据,采用蒙特卡罗法对定位误差进行仿真试验。试验结果表明该技术能够在误差允许范围内,在GPS定位系统失效的情况下完成无人机的自主定位     

直升机机载软件重要度分级的研究与应用

随着现代电子计算机技术在直升机中的大规模使用,机载软件在直升机中承担着日益重要的角色.机载软件不仅存储和处理大量对安全飞行至关重要的数据,还能辅助飞行人员进行逻辑判断、引导飞机进入正确的航线乃至直接控制飞机的飞行.为了确保机载软件正常的生命周期,稳步提高机载软件的安全性水平,开展机载软件重要度分级的研究与应用.     

基于图像匹配的飞行器导航定位算法及仿真

在飞行器导航定位优化控制的研究中,针对无法获得GPS信号时,长航时飞行器捷联惯导系统存在误差,提出了关于图像地标的飞行器精确定位算法,为实现成像系统对捷联惯导系统的误差校正奠定了基础。利用特定地标在机载摄像机像平面上的图像信息,通过图像变换、匹配定位、坐标变换,解算摄像机空间三维坐标和三个姿态角。再根据摄像机坐标系与机体坐标系的变换关系,推算飞行器精确位置。通过计算机仿真对算法进行了验证,结果表明,提出的算法能够满足GPS不可用时长航的飞行器组合导航精度要求,研究结果对长航时飞行器导航具有一定借鉴和参考价值。     

基于POS数据的OMIS影像几何校正

介绍了基于POS数据对OMIS影像做几何校正的原理和方法,不同于传统使用地面控制点对影像的纠正,该方法不需要地面控制点,这显著地提高了航空摄影后处理的工作效率,具有良好的应用前景。该处理流程主要分为两个部分:利用POS数据计算影像外方位元素和建立共线方程对OMIS影像做几何校正。实验证明,该方法对摆扫型成像方式的几何畸变校正是可行的,校正结果满足使用要求。     

Interface methods for using intranet portal organizational memory information system

In this paper, an intranet portal is considered as an information infrastructure (organizational memory information system, OMIS) supporting organizational learning. The properties and the hierarchical structure of information and knowledge in an intranet portal OMIS was identified as a problem for navigation tools of an intranet portal interface. The problem relates to navigation and retrieval functions of intranet portal OMIS and is expected to adversely affect user performance, satisfaction, and usefulness. To solve the problem, a conceptual model for navigation tools of an intranet portal interface was proposed and an experiment using a crossover design was conducted with 10 participants. In the experiment, a separate access method (tabbed tree tool) was compared to an unified access method (single tree tool). The results indicate that each information/knowledge repository for which a user has a different structural knowledge should be handled separately with a separate access to increase user satisfaction and the usefulness of the OMIS and to improve user performance in navigation.     

一种基于位置点的地图匹配改进算法

针对智能手机计算资源有限、功耗要求高、内置GPS模块易受到周围环境的影响等问题, 提出了一种改进的基于位置点的地图匹配算法, 利用用户个人位置移动的连续性, 结合历史轨迹数据进行道路投影, 通过纠偏的方法对手机的定位数据与电子地图数据进行匹配, 实现了直线道路、十字路口以及多边形区域等各种路况的准确定位。地图匹配算法可用于移动用户行为轨迹的监测和基于移动用户位置的个性化推荐中。     

Interface methods for using intranet portal organizational memory information system

In this paper, an intranet portal is considered as an information infrastructure (organizational memory information system, OMIS) supporting organizational learning. The properties and the hierarchical structure of information and knowledge in an intranet portal OMIS was identified as a problem for navigation tools of an intranet portal interface. The problem relates to navigation and retrieval functions of intranet portal OMIS and is expected to adversely affect user performance, satisfaction, and usefulness. To solve the problem, a conceptual model for navigation tools of an intranet portal interface was proposed and an experiment using a crossover design was conducted with 10 participants. In the experiment, a separate access method (tabbed tree tool) was compared to an unified access method (single tree tool). The results indicate that each information/knowledge repository for which a user has a different structural knowledge should be handled separately with a separate access to increase user satisfaction and the usefulness of the OMIS and to improve user performance in navigation.     

以人工标志物为基准的无人机定位系统

设计了一种以STM32单片机为控制核心的短距离高精度定位系统.系统通过识别定点位置的单一颜色块作为标识物来控制无人机不断飞到标识物上空,从而实现精准定位.本系统基于OV7670+STM32的结构开发,通过OV7670采集图像存储在FIFO中;STM32通过读取FIFO中的数据进行颜色识别与跟踪.实验结果表明,本系统识别准确率较高,定位精度较GPS定位提高了一个量级.     

GPS accuracy estimation using map matching techniques: Applied to vehicle positioning and odometer calibration

A test-bed application, called Map Matched GPS (MMGPS) processes raw GPS output data, from RINEX files, or GPS derived coordinates. This developed method uses absolute GPS positioning, map matched, to locate the vehicle on a road centre-line, when GPS is known to be sufficiently accurate. MMGPS software has now been adapted to incorporate positioning based on odometer derived distances (OMMGPS), when GPS positions are not available. Relative GPS positions are used to calibrate the odometer. If a GPS position is detected to be inaccurate, it is not used for positioning, or for calibrating the odometer correction factor. In OMMGPS, GPS pseudorange observations are combined with DTM height information and odometer positions to provide a vehicle position at ‘1 s’ epochs. The described experiment used GPS and odometer observations taken on a London bus on a predefined route in central of London. Therefore, map matching techniques are used to test GPS positioning accuracy, and to identify grossly inaccurate GPS positions. In total, over 15,000 vehicle positions were computed and tested using OMMGPS.In general, the position quality provided by GPS alone was extremely poor, due to multipath effects caused by the urban canyons of central London, so that odometer positioning was used much more often to position the vehicle than GPS. Typically, the ratio is 7:3 odometer positions to GPS positions. In the case of one particular trip, OMMGPS provides a mean error of position of 8.8 m compared with 53.7 m for raw GPS alone.     

基于卡尔曼滤波的车载GPS定位研究

利用卡尔曼滤波处理GPS定位数据是提高GPS定位精度的一种有效手段。针对车载GPS定位的特点,实现了一种车载GPS卡尔曼滤波算法。通过对实测数据进行比较分析,证明该算法具有实用意义。     

Localization using GPS and VISION aided INS with an image database and a network of a ground-based reference station in outdoor environments

GPS/INS integrated systems do not guarantee robustness and accuracy of localization, because GPS has vulnerability to external disturbances. However, the overall performance and reliability of the system can be significantly improved by fusing multiple sensors with a different operating principle. In outdoor environments where GPS may be blocked, there are many features compared to the open space and these features can provide much information for UGV localization. Thus, this paper proposes an improved localization algorithm based on the hierarchical federation of three measurement layers, i.e., GPS, INS, and visual localization, to overcome the shortcomings of GPS/INS integrated systems. The proposed algorithm automatically switches the operation modes according to GPS status and a network of a ground-based reference station. A vocabulary tree with SURF is used in the visual localization method. In the data fusion of visual localization and INS, an asynchronous and time-delayed data fusion algorithm is presented because visual localization is always time-delayed compared with INS. By using DGPS to obtain the reference position under the dynamic conditions of the reference station, the restrictions of the conventional DGPS are overcome and all UGVs within WiBro communication range of the reference station can accurately estimate the position with a common GPS. The experiment results with a predefined path demonstrate enhancement of the robustness and accuracy of localization in outdoor environments.     

An integrated data system for airborne remote sensing

This paper outlines the rationale and design for an enhanced Airborne Remote Sensing (ARS) facility, being implemented by the Natural Environment Research Council (NERC) in the U.K., to support environmental research and monitoring. It is based on the provision of a suite of optical remote sensing instruments, available for year-round deployment, and the development of an on-board integrated data acquisition, and ground-based data processing, system. Acquisition of the remotely sensed data will be synchronized with attitude/position information from a global positioning satellite (GPS) system to enable an accurate geometric rectification to be performed. A strategy has been devised for the endto-end ground processing of this data to enable the production of standard data products and distribution in a sensor-independent data format. The facility has been fully operational from Spring 1997 and is ready to support the needs of environmental scientists and organizations requiring high quality, and immediately usable, airborne remotely sensed data products.