Artists do not study perspective as much these days as in the past. Possibly only those who put together a montage of disparate elements to make up a scene would need to work out the perspective of each part, but I will post a diagram and some formulas I derived from spherical trigonometry to show how to convert from the left handed Cartesian co-ordinate system to the equivalent view in spherical trigonometry and this page from the book "Landscape Perspective" I am not really trained in math and so all I use are right triangles; which of course are easier. First of all the angle of view we see in sharp focus, not including our peripheral vision, from the horizon to the ground is the arc tan of 1/4. In other words if your eye line were at the altitude of 5 feet then you could only see all of a ten foot high elephant if it were at least twenty feet away; without bending your head.
bambootiger 
Obviously working out each point in perspective using trigonometry would be too time consuming to be ppractical, but it is a good place to start to understand the relationships. I have worked out a much easier way of doing it, that is perspective without being a slave to vanishing points. I’ll discuss that in another blog entry.