Welcome

1/28/2004 slide 18

Ecological Development
of Vision 3/3

•“…objects don’t go out of their way to line up in confusing arrangements.” [Pinker 1999] p212

•Cohesion makes smooth contours

•Motion, tension, gravity cause straight lines, right angles

•Near-parallel lines in image or from one point of view usually relate to parallel lines real world

•Organisms that move evolve to be symmetric

•Objects look different under different lighting, but important to be able to identify them nevertheless

light from above

shadow

Light from above

shadow

tree makes 90-degree with ground

Animal symmetrical along
long
axis

Ground continuous

Tree sort of symmetric


	Tree: ground is continuous,, tree is continuous
	Tree straight line, right angle to ground
	Parallel sides of trunk indicate parallel side in real world
	Cheetah-symmetric, lighting from above,
	Lots of dots but we see as one coherent animal. Grass has texture but we can discern plane it is on.