if you had a displacement map texture with a full mip chain. and each mip was the maximum heights (not the average height) scaled down of the mip before it, wouldnt that be a way to reduce texture sampling - marching the ray across?
How come this has never come up anywhere on the net? (as far as ive checked) Does it suck compared or not work?
It would require sampling a desired level, so youd have to make sure you stopped at the right from eye distance.