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What's The Difference?

ZBrush Usage Questions
#1

I’ve just realised something I’ve had wrong for a long time now, regarding bump, displacement, and normal maps.

  • I know that bump-mapping does not have geometric bumps.
  • I know that displacement-mapping does have geometric bumps.
  • I therefore, do not understand what normal-mapping does.

What’s the difference between normal and bump-mapping, and/or normal and displacement-mapping?

I keep seeing all these complaints about not being able to use the HD stuff, and without understanding the differences, I’m finding it hard to understand the importance of it in their pipeline and such.

Oh, and I still can’t find what that 3D cube reference tool was called or how to access it.

Cheers.

#2

How bump maps work is that they read a greyscale height map and use it to move the normals of your mesh so that the mesh appears ‘bumpy’ when rendered. This requires a calculation for each pixel rendered from your mesh. So some smart guy somewhere figured that instead of doing the calculation every frame, why not just do it once, store the result and apply it directly.

And that’s what a normal map is, instead of the greyscale height map, it has a map of the ‘bumped’ normals instead. The direction of the normal is stored in the form of the RGB colors.

#3

Ah, that makes sense - thanks for the explanation.

So if it were to be used in, say, a game engine, then it would still not give a geometric bump, but it’s preferred over bump mapping because the engine only needs to calculate it once?

There are no ‘visual’ differences between bump and normal mapping - is that what you’re meaning?

#4

Yes thats why games normally use normal maps and not bump maps cause they are much cheaper to calculate. For geo bumping you need some form of displacement mapping.

About visual differences, theoretically there is no difference but in practice it depends on what the renderer is doing with them. eg some apps may not do nice sharp bumps but may do nice normal maps. Or vice versa. You have to test it out to see what works better for you.

#5

I learned a lot about the different maps on the ZBrush WIKI Take care…MG

#6

Thanks, you two :+1:

I’m not really in need of using it just yet to be honest. It was more out of curiosity really.
At least now I know how it works, Cheers!

As for the Wiki, I’m surprised it’s even in there at all, so never thought of using it.
Anyway, I found it in there, and it was well documented.