Now FET may dispute that light travels in straight lines, but that is nothing to do with perspective. Moreover perspective collapses entirely if light is bendy.
I don't think, perspective, which is a mathematical projection from real world to an image plane, may not be possible with "curved rays". BTW. Mr Rowbotham denies any refraction and curvature of Earth, and that's the reason, why he had come up with this abstruse "law of perspective".
These effects similar to the "ship sinking behind the horizon" seem not so rare, so he had to find alternate way to explain it.
I agree, but the claim was that the ankles will always be visible on a flat earth, so long as light travels in straight lines.
These 'ankles' may be visible until you reach observers eye resolution. But this is not perspective.
Alone defining a 'distance' to an
imaginary point, the vanishing point, is utter nonsense.
Defining this distance by hight of the observer and eye resolution, turns around the projection. The distance, where objects 'vanish' due to resolution, is given by the object size and eye resolution.
Do you think, you get better eye resolution and see the same object farther away, if you climb a ladder or so?
(assuming in both cases there's no obstruction between you and the object)
Why is eye resolution so "surface affine"? Does it make any difference, if the observed object is close to the ground or higher up? Where would e.g. a hat, on the head of the girl, same size as here ankles, 'vanish' from view?