区域似大地水准面精化模型算法的优选

建立高精度、高分辨率的区域似大地水准面模型是GPS高程测量在实际应用中必须解决的首要问题,分别介绍BP神经网络、曲面拟合的模型及算法,并基于焦作市GPS测量数据,通过MATLAB编程计算和分类实验,验证几种算法的有效性与可靠性,结果证明神经网络算法要优于其它算法,最后给出有益的结论.     

高重复率SLR数据预处理方法的实现

千次重复频率SLR技术主要优势是观测数据量犬,从而得到高精度测量结果,相比低重复频率(小于10Hz)测距资料,kHz数据量有近百倍的增加,因而快速、有效对每次每圈卫星kHz资料处理是高重复率激光测距重要内容,以满足ILRS对测距数据及时处理和发送的要求.通过采用均匀选取数据的点图方式,加速数据点屏幕显示;采用Visua...     

室内定轨移动摄影测量控制系统设计与实现

在室内定轨移动摄影测量系统中,自动化、智能化的控制系统是其稳定可靠工作的重要保障.该摄影测量系统需要对轨道上的移动平台和摄影测量机构进行远程操作,为了实现稳定、可靠的控制,设计研发以单片机为控制核心的遥控系统;摄影测量机构是由五台非量测数码相机拼接而成,为了实现五台相机同步摄影,设计完成相机同步曝光装置.实验表明该系统...     

Skyline-based registration of 3D laser scans

Acquisition and registration of terrestrial 3D laser scans is a fundamental task in mapping and modeling of cities in three dimensions. To automate this task marker-free registration methods are required. Based on the existence of skyline features, this paper proposes a novel method. The skyline features are extracted from panoramic 3D scans and encoded as strings enabling the use of string matching for merging the scans. Initial results of the proposed method in the old city center of Bremen are pre-sented.     

Analytical methods for error propagation in planar space–time prisms

The space–time prism demarcates all locations in space–time that a mobile object or person can occupy during an episode of potential or unobserved movement. The prism is central to time geography as a measure of potential mobility and to mobile object databases as a measure of location possibilities given sampling error. This paper develops an analytical approach to assessing error propagation in space–time prisms and prism–prism intersections. We analyze the geometry of the prisms to derive a core set of geometric problems involving the intersection of circles and ellipses. Analytical error propagation techniques such as the Taylor linearization method based on the first-order partial derivatives are not available since explicit functions describing the intersections and their derivatives are unwieldy. However, since we have implicit functions describing prism geometry, we modify this approach using an implicit function theorem that provides the required first-order partials without the explicit expressions. We describe the general method as well as details for the two spatial dimensions case and provide example calculations.     

Spatial Metrics to Analyse the Impact of Regional Factors on Pattern of Urbanisation in Gurgaon,India

In recent years, there has been lot of emphasis on the study of urban land use/ land cover changes to discover the growth pattern due to rapid urbanisation. This study presents spatial metrics and gradient analysis approach for quantifying and capturing changes in urban landscape using LISS III imagery of 1999, 2001 and 2004 of Gurgaon, India. A combination of spatial metrics i.e. percentage of landscape, mean patch size, number of patches, landscape shape index and largest patch index, available in Fragstats ver. 3.3, have been used to quantify the patterns of urban growth in different directions in terms of size, shape and complexity of development. The local built-up areas were quantified by the “moving window” technique. A gradient analysis has been carried out through sampling from a reference point to 8 km in 16 directions with a window size of 500 mts. Results of this study demonstrate the potential of spatial metrics and gradient modelling to quantify the impact of regional factors on the growth pattern of Gurgaon city.     

The ionosphere: effects,GPS modeling and the benefits for space geodetic techniques

The main goal of this paper is to provide a summary of our current knowledge of the ionosphere as it relates to space geodetic techniques, especially the most informative technology, global navigation satellite systems (GNSS), specifically the fully deployed and operational global positioning system (GPS). As such, the main relevant modeling points are discussed, and the corresponding results of ionospheric monitoring are related, which were mostly computed using GPS data and based on the direct experience of the authors. We address various phenomena such as horizontal and vertical ionospheric morphology in quiet conditions, traveling ionospheric disturbances, solar flares, ionospheric storms and scintillation. Finally, we also tackle the question of how improved knowledge of ionospheric conditions, especially in terms of an accurate understanding of the distribution of free electrons, can improve space geodetic techniques at different levels, such as higher-order ionospheric effects, precise GNSS navigation, single-antenna GNSS orientation and real-time GNSS meteorology.     

Transverse Mercator with an accuracy of a few nanometers

Implementations of two algorithms for the transverse Mercator projection are described; these achieve accuracies close to machine precision. One is based on the exact equations of Thompson and Lee and the other uses an extension of Krüger’s series for the mapping to higher order. The exact method provides an accuracy of 9 nm over the entire ellipsoid, while the errors in the series method are less than 5 nm within 3900 km of the central meridian. In each case, the meridian convergence and scale are also computed with similar accuracy. The speed of the series method is competitive with other less accurate algorithms and the exact method is about five times slower.     

基于遥感数字图像的电子教学地图的制作

随着现代化教学手段在地理教学中的应用,传统的教学挂图可利用计算机作为辅助工具,制作成电子教学地图。本文论述了利用遥感数字图像制作电子教学地图的指导思想、必要性和可行性,并探讨了遥感数字影像教学地图的制作方法。     

基于分布式GIS的工程移民管理系统设计与实现

针对工程移民管理信息化建设的现状,提出以基于GIS的分布式处理技术为指导,采用.Net分层架构技术构建工程移民管理系统。阐述基于抽象工厂的分层架构体系,以解决数据库变更导致系统不兼容的问题;设计多级树模型,以解决移民实物指标动态管理的问题;重点探讨采用分布式空间数据库技术实现海量时空数据的高效存储管理,从而便于完成复杂...