Steep parallax mapping (as proposed by McGuire, 2005) retains the illusion of depth at steep angles even with high-energy height fields. The associated cost of a much more computationally intensive shader far more advanced GPU requirements, make this shader very GPU intensive. Note the staircase artifacts at the near of the quad, given by the piecewise linear search. Although this can be arbitrarly reduced by controlling the number of steps to run per-pixel, this would likely make the rendering cost unacceptable. Also notice 'texture bleeding' on the far end of the quad. Because the texture is used in REPEAT mode, the traced rays do traverse the other end of the quad (those spike-like detail should really be near the eye, just below the stair-like thing).