按照我的理解来计算重力矢量不是elipsoid saficient计算正常,但是我们需要计算机正常(大地水准面)[1](根据定义大地水准面是一个表面重力无处不在垂直)。所以我有一些问题:1。如何计算大地水准面正常吗?2。之间的最大差异是什么角度elipsoid正常和大地水准面正常吗?[!(在这里输入图像描述)[2]][2][![在这里输入图像描述][3]][3]* *更新:关于重力实际应用正常* *:我有一些高大的对象,站在地球上(像比萨斜塔)我可以获得GPS坐标的顶部和底部用照片从空气和应用摄影测量方法。然后从GPS坐标的顶部和底部的对象我能得到向量ECEF坐标,找到角在这个向量和重力向量。还我的问题:如果不同夹角椭球正常和大地水准面正常(“垂直偏差”)是大约100秒弧(0,0277778度)是安全这个实际应用椭球正常? **Update 2:** First: I'm trying to understand if normal to ellipsoid is sufficient for practical application. In real life object is mounted by using [spirit level][4] and on this picture we can see that theoretically I need normal to geoid, but if deflection of vertical small enough I can use normal to ellipsoid as approximation. [![enter image description here][5]][5] Second: I'm trying to estimate the error of angle measure, I have some error in calculating of GPS positions of my object top and bottom points say epsilon_1, also I have some error in calculating gravity vector because of I'm using normal to elispoid say epsilon_2 and I'm trying to understand how epsilon_1 and epsilon_2 affects resulting angle between object vector and gravity vector. [1]: https://en.wikipedia.org/wiki/Geoid [2]: http://i.stack.imgur.com/jwtBH.gif [3]: http://i.stack.imgur.com/5hkBm.png [4]: https://en.wikipedia.org/wiki/Spirit_level [5]: http://i.stack.imgur.com/zhCyA.gif