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Difference between parallax and steep parallax mapping?

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Parallax mapping is just a single offset based on the height where the normal is located, it isn't very accurate as its just a wild guess. The steep one probably attempts to trace the ray along the height map and find a collision point so it is more accurate although slower.

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Have a look here: http://graphics.cs.brown.edu/games/SteepParallax/index.html (sample fragment program at the bottom)
Basically, they implement a ray-tracer in the fragment program to find the actual u,v and create occlusion and self-shadowing. Pretty damn neat, but of course also more expensive than plain parallax.

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Quote:

they implement a ray-tracer in the fragment program to find the actual u,v

that sounds like Parallax Occlusion Mapping. Where's the difference?

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Quote:
Original post by m4gnus
that sounds like Parallax Occlusion Mapping. Where's the difference?


Everybody that comes up with a slightly different way of doing things will come up with their own terms to describe this technique. So in order to accurately know what the differences are, you need to look at the actual details of implementation and not at the names.

I guess they're pretty similar, but maybe one uses a volumetric distance map, another one a different acceleration structure or another one is brute force with a regular map or some dichotomy scheme, one actually works with antialiasing etc.

One needs to come up with a survey of techniques, but of course it pays less than to come up with one's own paper, and nobody wants to acknowledge too much their competition.

It seems that there is bunch of terms that describe similar looking techniques :
- Per pixel displacement : William Donnelly (in GPU gems)
- Displacement mapping : Microsoft (in their sdk)
- Parallax occlusion : ATI (in their toyshop demo)
- Steep parallax mapping : this Brown paper. Apparently they use LOD and filtering not to miss features. And they combine it with self shadowing.
- Relief mapping : Fabio Policarpio original paper.
- Parallax mapping : several games developers including Chaos Theory developers.

LeGreg

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