Finding correct AoA for camera movement

[Diehard@Azeroth]

How do find the correct Angle of Attack value for a unit moving on steep mountains or lower ground?

P.S: im thinking its the angle between two 3d vectors, the first vector being the x,y,z of the unit, and the other vector being the sight range distance from the first vector.

*Also using a third person camera if it makes a difference.

Thanks in advance