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Astronomical-topographic levelling using high-precision astrogeodetic vertical deflections and digital terrain model data 总被引:1,自引:1,他引:1
At the beginning of the twenty-first century, a technological change took place in geodetic astronomy by the development of
Digital Zenith Camera Systems (DZCS). Such instruments provide vertical deflection data at an angular accuracy level of 0.̋1
and better. Recently, DZCS have been employed for the collection of dense sets of astrogeodetic vertical deflection data in
several test areas in Germany with high-resolution digital terrain model (DTM) data (10–50 m resolution) available. These
considerable advancements motivate a new analysis of the method of astronomical-topographic levelling, which uses DTM data
for the interpolation between the astrogeodetic stations. We present and analyse a least-squares collocation technique that
uses DTM data for the accurate interpolation of vertical deflection data. The combination of both data sets allows a precise
determination of the gravity field along profiles, even in regions with a rugged topography. The accuracy of the method is
studied with particular attention on the density of astrogeodetic stations. The error propagation rule of astronomical levelling
is empirically derived. It accounts for the signal omission that increases with the station spacing. In a test area located
in the German Alps, the method was successfully applied to the determination of a quasigeoid profile of 23 km length. For
a station spacing from a few 100 m to about 2 km, the accuracy of the quasigeoid was found to be about 1–2 mm, which corresponds
to a relative accuracy of about 0.05−0.1 ppm. Application examples are given, such as the local and regional validation of
gravity field models computed from gravimetric data and the economic gravity field determination in geodetically less covered
regions. 相似文献
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基于面向对象编程原理,对数字地图的符号按面向对象的分类方法进行分类,详细说明了各类数字地图符号在计算机上的绘制方法,并在对线状符号的处理上改进了以往的传统做法,提出了新的思路,使程序实现更为方便,提高了程序执行效率。 相似文献
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基于基准地价系数修正法的城镇土地估价系统实现 总被引:1,自引:0,他引:1
郑智华 《测绘与空间地理信息》2007,30(1):98-101
本文以Visual FoxPro6.0为开发工具,实现高级语言与数据库之间的数据传输,建立了基于基准地价系数修正法的城镇土地估价信息系统,包括系统分析、系统总体框架设计、功能模块设计等,实现了土地估价的科学化、自动化和可视化。 相似文献