lkendall opened this issue on Dec 18, 2007 · 76 posts
bagginsbill posted Tue, 18 December 2007 at 10:27 PM
Let me clarify.
A normal map defines a purturbation of the normal - i.e. which way the surface faces. It records this information as a unit vector - which for purposes of storing as an image turns into RGB values.
But 256 levels is all you get for each, because each channel has only 8 bits. So you end up with vectors that are not perfect in the sense that magnitude is not always exactly one. Also, because the resulting normal depends non-linearly on the original dialed-in bump, you can't just willy nilly change the amount of bumpiness as easily as you can with a bump map.
In particular, I can disturb a bump map with other math functions, modulating it so that I can make it more or less in different areas (or at different times during an animation). This makes bump maps potentially much more flexible and dynamic than normal maps, which are essentially frozen-in-time snapshots of the resulting normal after applying a bump map.
So bump maps give me more control and I can generate them on the fly using math, giving very high resolution.
A normal map must be baked and stored in 8-bit-per-channel images. Not so good.
In other words, if normal maps are hard to make, cannot be dynamically changed using math/masks, and are limited in resolution, they are inferior to bump maps, IMO.
And BOTH are inferior to displacement, which as some have pointed out, I have used to create 3-D sculpted objects from otherwise featureless primitives. Vector displacement (where I could give the actual direction) would be even more sweet.
As far as I've been able to see (because I have it for Beta), Poser Pro doesn't have any of this, other than the Gradient Bump we've always had, which is a Normal map data interpreter. I don't remember what style it is. But somebody else posted a normal map built in some other tool used in Poser plugged into the Gradient bump channel. Try it.
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