If you surround the bird B with a ten-meter-radius sphere and map each point A on the ground to the intersection between the line segment AB and the sphere, the x and y axis map to a total of four curves along the lower half of the sphere, all of which are, in fact, parallel at the equator.
This way, only smaller parts of lines are parallel (parallel enough), while in reality—or should I say, on the plane—the biggest part of those lines are parallel.
Mapping on the sphere, even mental, doesn’t account for that. And the bird must know this, because it flies miles and miles.
Most of reality maps to near the equator, therefore the bird’s eye would evolve to have most receptors near the equator and most of its visual cortex would focus there. (Assuming that things don’t become more important to the bird as they grow nearer :P)
If you surround the bird B with a ten-meter-radius sphere and map each point A on the ground to the intersection between the line segment AB and the sphere, the x and y axis map to a total of four curves along the lower half of the sphere, all of which are, in fact, parallel at the equator.
This way, only smaller parts of lines are parallel (parallel enough), while in reality—or should I say, on the plane—the biggest part of those lines are parallel.
Mapping on the sphere, even mental, doesn’t account for that. And the bird must know this, because it flies miles and miles.
Most of reality maps to near the equator, therefore the bird’s eye would evolve to have most receptors near the equator and most of its visual cortex would focus there. (Assuming that things don’t become more important to the bird as they grow nearer :P)