Convert relative to global

1. Sep 2, 2009

mamali

could any one help me ?
i know global position of three flag for example (10,20,30)
and i have my distance , phi and theta to flags .
could any one helping me find my position ?

2. Sep 3, 2009

HallsofIvy

What do you mean by "three flags"? You give the position, (10, 20, 30) of one point. But knowing the coordinates of a single point and your position relative to that point is sufficient. Your x, y, z coordinates, taking that one point as origin are x= $\rho cos(\theta) sin(\phi)$, y= $\rho sin(\theta) sin(\phi)$ and z= $\rho cos(\phi)$. Your x, y, z "global" coordinates, relative to the same coordinate system in which your point is (10, 20, 30) are x= $\rho cos(\theta) sin(\phi)+ 10$, y= $\rho sin(\theta) sin(\phi)+ 20$ and z= $\rho cos(\phi)+ 30$, a simple translation.

I am assuming here that your "$\theta$" and "$\phi$ are relative to the "global" coordinate system. If not, you might need three points and would need to specify how $\theta$ and $\phi$ are measured.