# [Bf-committers] So

Kiernan Holland bf-committers@blender.org
Sun, 11 Jan 2004 22:13:33 -0700

```Normal Vector = (R,G,B), where R,G,B are unit vectors? How does it
represent negative quantities?
This sounds a little bit like implementing things like glittery surfaces,
which are not possible with
bump mapping, which just rotates the normal relative to peaks and bases..
Blender's bump maps
in the past seemed to be derived from a mesh of 2nd order curve fitting,
with the U and V
producing squarish hills.. That's a problem of how one goes from a
grey-scale image to a
bump map.. You could also derive a bump map based on parametric function,
where
instead of having normal based on f(u,v), you have it based on solid
coordinates f(x,y,z)..
Or you could take it s step further: f(u,v)ijk = r(u,v)i + g(u,v)j +
b(u,v)k
where ijk are unit vectors, and u,v is coordinates in image space, and
r,g,b  represents
a unique color channel in the image space.. f(u,v)ijk = normal used in
computing a bump map..