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IONOSPHERIC EFFECTS ON GPS NAVIGATION IN LOW-LATITUDE AREA

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IONOSPHERIC EFFECTS ON GPS NAVIGATION IN LOW-LATITUDE AREA

基于改进SURF算法的无人机遥感影像快速拼接

第一届交通运输工程国际学术会议

作者： GAO Shan1, 2.and CHEN Wu2.1school of Civil engineering, Southwest Jiaotong {2., Chengdu, Sichuan, china, 610031 2.ept. of land surveying and Geo-Informatics, The Hong Kong polytechnic {2., Hong Kong

Ionospheric effects are the major constraints for GPS navigation. Especially, at low latitude, ionospheric delay varies greatly both in space and time. Even for short baselines, ionospheric effects cannot be cancelled out with double difference algorithm. Strong ionospheric disturbances are also observed in the region. In this paper, ionospheric behavior in Hong Kong is investigated by using a dense reference network. The effects of ionospheric disturbances on GPS receiver, such as loss of lock, gross error and measurement noise are studied.

关键词： GPS navigation ionospheric delay loss of lock cycle slip

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地理与地理信息科学 2013年第5期29卷 22-25,F0002页

作者：李长春齐修东雷添杰马萧萧河南理工大学测绘与国土信息工程学院河南焦作454001 北京师范大学北京100875

为了及时、准确地反映测区情况，需要在拍摄现场将获得的无人机遥感影像进行实时拼接。基于SURF的无人机遥感影像拼接算法具有尺度和旋转不变性，拼接效果较好，但该算法稳定性较差，拼接过程中大量误特征点被提取出来，导致计算量大、... 详细信息

为了及时、准确地反映测区情况，需要在拍摄现场将获得的无人机遥感影像进行实时拼接。基于SURF的无人机遥感影像拼接算法具有尺度和旋转不变性，拼接效果较好，但该算法稳定性较差，拼接过程中大量误特征点被提取出来，导致计算量大、匹配效率低，无法满足实时拼接的要求。该文首先利用SURF算法粗提取特征点，然后利用RANSAC算法剔除被误提取的特征点，实现特征点的快速匹配和图像实时拼接。实验结果表明该文的算法不但可以得到很好的图像拼接效果，而且极大地提高了拼接效率。

关键词：无人机遥感影像快速拼接 SURF算法 RANSAC算法改进SURF算法

Monitoring Crustal Deformations with Radar Interferometry: A Review

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Journal of Southwest Jiaotong university(English Edition) 2004年第2期12卷 148-158页

作者：刘国祥丁晓利黄丁发 school of Civil engineering Southwest Jiaotong University Department of land surveying and Geo-Informatics The Hong Kong Polytechnic University

The crustal movements, probably motivating earthquakes, are considered as one of the main geodynamic sources. The quantitative measurements of ground surface deformations are vital for studying mechanisms of the buried faults or even estimating earthquake potential. A new space-geodetic technology, synthetic aperture radar interferometry (InSAR), can be applied to detect such large-area deformations, and has demonstrated some prominent advantages. This paper reviews the capacity and limitations of InSAR, and summarises the existing applications including some of our results in studying the earthquake-related crustal motions. Finally it gives the outlook for the future development of InSAR.

关键词： Satellite SAR interferometry Earthquake Crustal deformation Monitoring

Stochastic Model of GPS/BD Combined Standard Single Point Positioning

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Stochastic Model of GPS/BD Combined Standard Single Point Po...

第三届中国卫星导航学术年会

作者： Wenkun Yu 1,Wujiao Dai 1,Xiaoli Ding 2.Wentao Yang 2.Xiao Gao 1 1 school of Geosciences and Info-physics engineering,Central South {2.,Changsha,Hunan,china 2.Department of land surveying and Geo-Informatics,The Hong Kong polytechnic {2.,Hung Hom,Kow Loon,Hong Kong

Reasonable determination of weights is the key factor in giving full play to advantages of GPS/BD combined ***,Helmert VCE （Variance Component Estimation） is employed aiming at adjusting the variance-ratio between the two heteroscedastic ***,the precise priori weight matrix can enhance the convergence of iteration methods based on posteriori information,reduce the iteration’s ***,system related errors,together with outliers,influence the estimation,leading to a distorted stochastic ***,in this paper,based on robust Helmert VCE and using integrated priori accuracy,taking various error sources into consideration,an initial weighing method for combined system is suggested.

关键词： GPS/BD robust Helmert stochastic model

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支持向量机在多类分类问题中的推广

计算机工程与应用 2004年第7期40卷 10-13,65页

作者：刘志刚李德仁秦前清史文中武汉大学遥感信息工程学院武汉430079 武汉大学测绘遥感信息工程国家重点实验室武汉430079 香港理工大学土地测量与地理咨询系地球信息研究中心

支持向量机(SVMs)最初是用以解决两类分类问题,不能直接用于多类分类,如何有效地将其推广到多类分类问题是一个正在研究的问题。该文总结了现有主要的支持向量机多类分类算法,系统地比较了各算法的训练速度、分类速度和推广能力,并分析... 详细信息

支持向量机(SVMs)最初是用以解决两类分类问题,不能直接用于多类分类,如何有效地将其推广到多类分类问题是一个正在研究的问题。该文总结了现有主要的支持向量机多类分类算法,系统地比较了各算法的训练速度、分类速度和推广能力,并分析它们的不足和有待解决的问题。

关键词：支持向量机多类分类多类支持向量机

A New GPS System for Continuous Deformation Monitoring

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Journal of Modern Transportation 2000年第2期17卷 169-176页

作者：黄丁发丁晓利阿永奇 school of Civil engineering Southwest Jiaotong University Chengdu 610031 China Department of land surveying and Geo-Informatics The HongKong Polytechnic UniversityKowloon HongKong

This paper presents a multi-antenna GPS based system developed for local continuous deformation monitoring. Due to a large number of points that needs to be monitored, the standard approaches of using permanent GPS receiver arrays will cause high cost. It eventually becomes the limiting factor for large-scale use of GPS in these application areas. Multi-antenna GPS system allows a number of GPS antennas to be linked to one GPS receiver by a specially designed electronic component, i. e. the so-called GPS multi-antenna switch (GMS), The receiver takes data sequentially from each of the antennas attached to the receiver. A distinctive advantage of the approach is that one GPS receiver can be used to monitor more than one point. The cost per monitored point (i. e. the expenses of hardware) is therefore significantly reduced.

关键词： multi-antenna GPS system deformation monitoring fast ambiguity resolution multipath

A VORONOI-BASED ALGORITHM FOR POINT CLUSTER GENERALIZATION

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A VORONOI-BASED ALGORITHM FOR POINT CLUSTER GENERALIZATION

第十一届几何与图学国际会议

作者： Haowen YAN Zhilin LILanzhou Jiaotong university Lanzhou 730070 chinaDepartment of {2. surveying and Geo-Informatics The Hong Kong polytechnic university Kowloon Hong Kong

＜正＞The main purpose of the algorithms for point feature generalization is to correctly transmit information contained by point clusters with the reduction of point number, however two groups of existing algorithms are not satisfactory: the incremental algorithms for settlement selection （Langran and Poiker, 1986;van Krevel et al, 1995） can’t deal with topological information well, while the Voronoi-based algorithm （Ai and Liu, 2.02. doesn’t take into consideration the importance values （thematic information） of points. To overcome their shortcomings, an integrated algorithm is given. The new algorithm employs two methods to ensure different kinds of information can be transmitted correctly: （1） determine the point number on resulting maps by the radical law （Topfer and Pillewizer, 1966）, so that statistical （positional） information is transmitted correctly;（2. recursively construct Voronoi diagrams of the retained points, and delete points by comparing the significance value of a point with those of its Voronoi neighbors, so that topological, thematic and geometrical information are transmitted correctly. The drawback of this algorithm is that the symbolization of point features is not considered, which may cause overlap and congestion of map symbols on resulting maps.

关键词： Point feature generalization Voronoi diagrams Algorithms

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无控制DEM匹配与地表差异探测

计算机工程与应用 2009年第31期45卷 193-195,226页

作者：冯义从岑敏仪张同刚黄志勤西南交通大学土木工程学院成都610031 四川省国土资源厅信息中心成都610072

泥石流爆发地区控制点布设和维护困难,使得精确探测该类区域泥石流造成的地表变化非常困难。基于规则格网DEM(Digital Elevation Model),分析泥石流灾害的特点,提出了顾及地形特征的无控制DEM匹配与差异探测方法。根据不同时相DEM数据,... 详细信息

泥石流爆发地区控制点布设和维护困难,使得精确探测该类区域泥石流造成的地表变化非常困难。基于规则格网DEM(Digital Elevation Model),分析泥石流灾害的特点,提出了顾及地形特征的无控制DEM匹配与差异探测方法。根据不同时相DEM数据,利用该方法成功探测出普歪沟泥石流爆发区的地表水土流失变化。

关键词：三维匹配差异探测稳健估计地形特征

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GIS空间分析的应用领域

四川测绘 2004年第3期27卷 99-102页

作者：姜亚莉张延辉武汉大学遥感信息工程学院湖北武汉430079 广东省国土资源厅海测队广东广州510500

随着地理信息系统的不断发展,对于空间数据结构的研究也日趋成熟,作为该系统的核心———空间分析也相应成为人们倍加关注的热点。本文从空间分析的定义、目的出发,进一步概括了GIS空间分析的具体应用领域,并结合参与的项目着重分析了... 详细信息

随着地理信息系统的不断发展,对于空间数据结构的研究也日趋成熟,作为该系统的核心———空间分析也相应成为人们倍加关注的热点。本文从空间分析的定义、目的出发,进一步概括了GIS空间分析的具体应用领域,并结合参与的项目着重分析了空间分析在水污染监测中的应用情况。

关键词： GIS 地理信息系统空间数据结构水污染监测