2 Dimensional parametric model of the camera positioning and aiming. Our view of this diagram is looking at the end of the pivot axis so we see the full length of the arm, as it moves from to 90º elevation down to 0º elevation. This diagram does not model rotation about the Z axis, although I can add that once this is clear. Adjust the elevation, arm length, and camera offset angle with the three sliders.
Note that Roffset is the radius of the circle whose points would appear in the center of the camera's image as the arm is rotated (Rz, not elevated). In 2 dimensions, it's the same as the (absolute value of the) X intersect value. Zoffset is the height above the origin (pivot axle) where the camera view ray intersects the vertical (Z) axis. Also, this 2D diagram gets the X axis OK, but it calls our Z axis (vertical) its Y axis. And just for fun, the Zintersect point is reported in polar coordinates.