Precise, automatic and fast method for vanishing point detection

A new automated approach for vanishing point detection in images of urban scenes is described. This method is based on the theorem of Thales. The main contribution of this paper is the automatic and simultaneous detection of all vanishing points of the image, achieved by converting this problem into the detection of circles in a complex cloud of points, in which each point corresponds to a segment and is associated with an uncertainty. This extraction of circles uses a RANSAC method, modified to improve its speed by using accumulation techniques (Hough transform or otherwise). This robust estimation is then refined by least squares error propagation using the individual variances of each segment. The algorithm is robust, its accuracy is optimised and it is entirely automatic. Its successful operation has been tested on a large number of images of varied urban scenes.     

三维激光扫描单点定位精度评定方法研究

三维激光扫描技术是当前的一种新技术,其仪器的精度评定方法还不完善,提出两种三维激光扫描单点定位精度评价方法,即外部符合精度评价方法和内部符合精度评价方法。介绍了两种方案的实施过程,并且通过实验进行了分析,得到了较好的评价结果。     

非量测数码相机单像空间后方交会的辅助分步像主距与像主点的简单测定

近年来,非量测的中、高端普通数码相机越来越多的应用到航空、近景等摄影测量领域[3]。影响摄影测量成果精度的重要因素之一是相机的技术参数,因此相机技术参数的检校是保证成果质量能否满足精度要求的关键问题之一。本文着重讲述了在以单像空间后方交会为基础的相机检校中,受制于实践环境,当控制场各控制点的几何分布通常被布置离一个平面不大的范围内,则会使未知数的解极不稳定,甚至有不定解得可能。为防止出现错解以及不定解,先通过试验场检校给出像主距f和像主点(x0,y0)初始值,从而避免上述情况发生,文中给出了方法、原理及实践数据、结果。     

面向流媒体传输的空间数据变化累积模型

将流媒体技术引入到以矢量数据为主的网络GIS传输中,其关键是建立逐级精细化的多层次表达模型,并在服务器端数据预组织上建立线性索引结构。本研究针对该目标建立一种矢量数据多重表达的新模型,即变化累积模型,认为尺度空间中从粗到细的数据表达过程是一些"变化"的累积,"变化"表现为两个连续尺度表达间的差别,通过"变化"元素的逐渐增加或减少来实现渐进传输。基于该模型对面状数据渐进式传输进行研究,将多边形分级剖分为一系列凸壳或外接矩形的基础上建立变化累积模型,通过剖分元素的组合完成渐进式流媒体传输。     

基于SAR干涉点目标分析技术的城市地表形变监测

通过深入研究干涉点目标的相位模型,提出基于空间搜索的邻近点目标干涉相位差解缠方法,用以计算点目标的地形残差和线性形变,以及分离点目标大气延迟相位和非线性形变相位的时空域滤波方法,解决干涉点目标分析中的关键问题.最后,以苏州地区地表沉降监测为应用试验,利用形成的SAR干涉点目标形变信息提取技术,获取苏州市区1992-2002年间的地表沉降信息.研究结果与已有文献记录保持比较好的一致性,证明SAR干涉点目标技术完全可以发展成为应用于城市地表形变监测的实用化技术.

Abstract：

Interferometric point target analysis (IPTA) is one of the latest developments in radar interferometric processing. It is achieved by analysis of the interferometric phases of some individual point targets, which are discrete and present temporarily stable backscattering characteristics, in long temporal series of interferometric SAR images. This paper analyzes the interferometric phase model of point targets, and then addresses two key issues within IPTA process. Firstly, a spatial searching method is proposed to unwrap the interferometric phase difference between two neighboring point targets. The height residual error and linear deformation rate of each point target can then be calculated, when a global reference point with known height correction and deformation history is chosen. Secondly, a spatial-temporal filtering scheme is proposed to further separate the atmosphere phase and nonlinear deformation phase from the residual interferometric phase. Finally, an experiment of the developed IPTA methodology is conducted over Suzhou urban area. Totally 38 ERS-1/2 SAR scenes are analyzed, and the deformation information over 3 546 point targets in the time span of 1992-2002 are generated. The IPTA-derivecl deformation shows very good agreement with the published result, which demonstrates that the IPTA technique can be developed into an operational tool to map the ground subsidence over urban area.     

利用TGO软件的点校正功能实现物探测量GPS控制网待定点的解算

基于泌阳凹陷高精度三维地震采集测量GPS控制测量项目,作者论述了在TGO软件中利用点校正功能求解控制网中待定点坐标方法。通过与约束平差结果的比较,证明了此方法的可行性。     

轨道平顺性与测量精度

从轨道平顺性验收标准性切入,提出轨道平顺性对控制网的精度要求;指出轨道平顺性与控制点间的相对精度相关,与控制测量网垂直于线路的的横向误差及高程相关。     

关于非齐次马氏链的强极限定理

主要研究了非齐次马氏链的强极限定理.首先应用鞅差序列收敛定理给出了关于非齐次马氏链的任意k元函数一类平均值的极限定理.最后得到一系列相关状态序偶出现频率的推论.     

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CG 2A型垂线观测仪固定式的使用

介绍CG-2A型垂线观测仪固定式的使用情况,并与便携带式进行了比较。