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《地图》1993,(3)
Profiles a. The study of land forms from an examina tion of the contour lines is adequate for many pur poses, but when precision is demanded, a profile is usually required. A profile, within the scope and purpose of this manual, is an exaggerated side view of a portion of the earth's surface along a line between two points. 相似文献
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《地图》1993,(2)
d. On maps where the index and intermediate contour lines do not show the elevation and relief as accurately as may be needed, supplementary contours may be used. These contour lines are dashed brown lines, usually at one-haft the contour interval for the map. A note in the marginal information indicates the interval used. They are used exactly as are the solid contour lines. e. In addition to the contour lines on maps, bench marks and spot elevation are used to indicate points of known elevation.Bench marks are usually symbolized by an X and the elevation is given at that 相似文献
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《地图》1992,(1)
For the least distortion the best map is one on a globe, since all the geographical relationships are correctly displayed. But globes are bulky, expensive, and do n t permit the entire surface to be seen at once. Flat maps are better for most purposes. Which projection is best for a world map? The flip answer is "none",but that is not a good question. A better question would be: Which map projection is best for what purpose? One can narrow the options by 相似文献
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本文综合叙述了ITRF的原点,尺度,定几以及关于垂直基准方向的问题,可供了解使用ITRF和参与ITRF有关工作以及事空间大地测量观测与数据处理者参考。 相似文献
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随着测绘技术的不断进步,GPS实时动态定位技术(RTK)在测绘领域的应用日益广泛,而基于VRS(虚拟参考站Virtual Reference Station)技术的出现,更是为RTK测量提供了新的技术平台,给测量行业带来了革命性的变化。本文结合实例简要介绍了基于VRS的RTK在测绘领域的应用,阐述了其优越性和不足之处。 相似文献
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论述了具有自主知识产权的网络GNSS增强虚拟参考站系统软件(VENUS)的总体设计和功能模块设计。该软件系统平台界面友好,商品化程度高,目前已投入实际网络的运行中,稳定性好。经统计,其实时动态定位(RTK)的外符合精度水平为2~3 cm,高程为3~6 cm;内符合精度水平为1~2 cm,高程为2~4cm;精度分布均匀,初始化时间短。 相似文献
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城市数字化和数字城市是现代化城市的发展趋势,空间数据基础设施是数字城市的基础,连续运行参考站系统是城市空间数据基础设施的重要组成部分。本文介绍了连续运行参考站系统(CORS),阐述了建立该系统的基本步骤和所具备的功能,重点论述了参考站系统建设中的关键技术。 相似文献