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I don't see height maps having any advantages over normal maps. It's just an extra layer that may mess up any existing normal map with details that are already present there. Are there any advantages to height maps?

I normally use height maps for skin pours on my characters but I find normal map still out classes it.

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  • $\begingroup$ If you're comparing bump vs normal map, I don't think there's a lot of notable differences. Bump map can be used for real displacement though, it is useful when the fake is too obvious, but in that case you need to have enough topology, so it makes your object heavier. Bump and normal maps are useful to fake and keep an object low-poly. $\endgroup$
    – moonboots
    Commented May 2, 2020 at 6:04
  • $\begingroup$ Hello :). The biggest advantage is ease of use. Literally any BW texture (tiny text, 2D graphics) can be used as a Bump map. But for proper Normal maps you need to bake real geometry, which isn't always convenient. $\endgroup$ Commented May 2, 2020 at 7:44

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A height map is useful if the camera is going to be close enough to the surface to "see through" the trickery of a normal map. A normal map leaves the surface where it is, and just changes how light reflects off; but if the "eye" is close enough that the difference in height itself would have been visible, that looks super weird.

Here's a heavily subdivided plane equipped with a normal map generated from a noise texture:

Subdivided plane with generic bump-map

And here's the same plane, with the same texture, except that this time it's treated as a height map:

Subdivided plane with generic height-map

Isn't the second one a thousand times more believable? The first one would be good enough if seen from a great enough distance, or if the bump-map were "weakened" so that it reflected much shallower bumps; but this close up, only the height map can be realistic.

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  • $\begingroup$ Thanks! Wow that's amazing they look like 2 completely different meshes. But why is the top one "close up" though? It looks like a regular distance from a plane to me. $\endgroup$
    – Jimmy Lin
    Commented May 2, 2020 at 6:04
  • $\begingroup$ Also doesn't height map make fake topology too? Only displacement maps truly modify geo. $\endgroup$
    – Jimmy Lin
    Commented May 2, 2020 at 6:30
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While Normal maps do offer higher quality, Bump maps are way easier to create.

Normal maps:

  • Carry more information (by using all three RGB channels)
  • Describe direction in 3D space
  • Need to be baked from real geometry (which isn't always possible)

Bump/height maps

  • Low quality, only BW input
  • Very easy to create (basically any BW image will do)
  • (Just to add: Bump maps are converted into normal maps before being rendered)

Bump maps vs proper Normal maps compared

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