Consider the diagram below:
We can see from the plane $\Phi$ two parallel lines on its surface. Then these two lines are projected onto the plane $\Pi$ where they appear to be intersecting.
My question is how did they become intersecting? and how is the perspective defined in this figure? that is to say from what field of view is the person looking at this diagram to see this phenomena? Because I don't understand what this diagram is specifically describing when it connects all these rays to the optical center $O$.
I have attached an example of train tracks and hope someone can help me understand it as an example of this phenomena
Best Answer
In the train track picture, the rails never meet, but appear to. The point where they appear to meet is infinitely far away, but there is a definite angle to look to see the point of intersection (we must look at the middle of the picture).
In the top diagram the observer at $O$ must look in the direction $O\Pi$ to see where the two lines appear to meet (even though they never actually meet).