Geometry and optical perceptions

[deleted-369737]

Hello.
My son has been asked to offer an explanation to the following optical effect. When the human eye sees objects aligned along a horizontal plane (e.g. posts along a wire fence) the objects appear to be closer together as their distance from the eye increases. I cannot think of the scientific name, or explanation for this optical perception. I am also unsure as to what extent parallax error is relevant here, because it is not so much the spacing between, but the apparent decreasing height of the aligned objects that should be the subject of any explanation.
We would greatly appreciate any help you might offer with this.
Thanking you in advance!
Keith.

[deleted-2131]

Hi Keith,

You are on the right track. It has to do with the angular size of objects as a function of distance. Take a look at this explanation, and post back if you have questions about it.
http://www.thenakedscientists.com/HTML/ ... tion/2180/