问题描述
我想更具体地说明我想做什么.我在ECI中获得坐标，因此需要从中获得纬度和经度.我能怎么做?我正在搜索，但找不到任何有关它的信息.再次感谢.
I would like to be more specific about what I want to do. I get coordinates in ECI and I need to get the latitude and longitude from this. How can I do? I was searching but I could'nt find anything about it. Thanks again.
(我正在用Java编写一个小程序，该程序显示给定时间内卫星的位置.因此，我使用了NORAD SGP算法，并且得到了位置(x，y，z)和速度(Vx (Vy，Vz).但是根据我所读的内容，此算法使用的坐标系是ECI，现在我需要在地图上绘制卫星，但无法将坐标转换为可以帮助我的系统.我想如果我可以将其转换为经度和纬度，则很容易绘制.您能帮我吗?我该怎么办呢?最好的选择是什么(UTM等)?谢谢.)
(I'm doing a small program in java that shows the position of a satellite in a given time. So, I used the NORAD SGP algorithm, and I have the position (x,y,z) and velocity(Vx,Vy,Vz). But the coordinates system used by this algorithm is the ECI, according what I read. Now I need to draw the satellite in a map, but I can't convert this coordinates to some system that could help me. I think if I can convert it to longitude and latitude it would be easy to draw. Could you help me? how can I do it? What is the best option(UTM,etc)? Thanks.)
推荐答案
您想要做的就是将ECI/ECEF(笛卡尔)转换为大地坐标(纬度/经度).该转换是所有大地测量转换中最复杂的，因为封闭形式的解决方案很复杂.有关坐标系的讨论，请参见史蒂文斯和刘易斯的飞机控制和模拟"的第34页: http://books.google.com/books/about/Aircraft_control_and_simulation.html?id=T0Ux6av4btIC
What you want to do is called ECI/ECEF (cartessian) to Geodetic (lat/lon) conversion. This conversion is the most complex of all the geodetic conversions as the closed form solution is complicated. See page 34 of Stevens and Lewis, Aircraft Control and Simulation for a discussion of the coordinate systems: http://books.google.com/books/about/Aircraft_control_and_simulation.html?id=T0Ux6av4btIC
ECI到大地测量是一个两步过程:
ECI to geodetic is a two step process:
第一步很简单，您需要将ECI(以地球为中心的惯性)转换为ECEF(以地球为中心/固定的地球).
The first step is the easiest in that you need to convert ECI (earth centered inertial) to ECEF (earth centered/earth fixed).
第二步是将ECEF转换为大地测量.您可以在此处阅读有关通过Newton-Ralphson解决此问题的信息: http://en.wikipedia.org/wiki/Geodetic_system
The second step is to convert ECEF to geodetic. You can read about solving this via Newton-Ralphson here: http://en.wikipedia.org/wiki/Geodetic_system
但是，如果我没记错的话，牛顿-拉夫森在两极周围变得不稳定.封闭式解决方案要复杂得多.我已经成功地实现了朱的方法.封闭形式解决方案的优点是没有迭代且没有奇点(技术上有奇点，但不在地球之上).参考文献:J.Zhu.将以地球为中心的地球固定坐标转换为大地坐标.技术报告IEEE日志号T-AES/30/3/1666，IEEE，1993年12月.
However, if I remember correctly, Newton-Raphson becomes unstable around the poles. The closed form solutions are much more complicated. I have successfully implemented Zhu's method. The advantage of the closed form solution is no iterations and there are no singularities (technically there are singularities but not above the earth). The reference: J. Zhu. Conversion of earth-centered earth-fixed coordinates to geodetic coordinates. Technical Report IEEE Log NO. T-AES/30/3/1666, IEEE, December 1993.
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