I'm not sure if this is the technical term, but I'm asking: At what rate do things scale bigger and smaller as they move toward and away from the human eye?
I know the equation for the linear perspective grids below are,
(size changed by this %) = 5/((distance to object) + 5) for the grid on the left
(size changed by this %) = 3/((distance to object) + 3) for the grid on the right
The '3's and the '5's come from the distance from the distance point to the vanishing point. On the grid on the right the objects smaller at a bigger rate as they move back than they do on the grid on the rate that has a distance point of 5.
for example: a circle with a 1' diameter at (distance to object) = 0
will be 0.5' at 5' away because...
0.5 = 5(5 + 5) = 5/10 = 1/2
I know one point perspective is not nearly the most accurate model, but I'm only interested is calculating the size of objects depending on their size, or vice versa. Maybe you have a better equations that scales objects the same way the eye perceives.
Right now I only know what it isn't. It's not depth of field because that has to do with what's in focus. It's not the range of vision in terms of degree or depth perspective because the eye(s) can see things shrink at the same rate with one eye looking at things going straight away from me.
In both of my grids the hieght from the horizon is 5' but things scale bigger and smaller at the same rates away from you whether you're on the ground or in a hot air balloon.
I suppose whatever the different setting there is between a fish eye and my eye is what I'm asking.
So, please. What is the distance point for the human eye?