Bump vs Displacement vs Normal Maps

Scavenger

Can anyone point me to a simple explanation of the differences between Bump Maps, Displacement Maps, and Normal Maps, and why you'd use one over the others?

Bump and Displacement seem to be very similar, and some vendors seem to use one or the other randomly.

Normal Maps seem to do similar to those, though they obviously look a lot different.

Richard Haseltine

Bump and normal fake relief - the renderer adjusts the intensity of the light as if the surface was facing in another direction. Bump is simpler to make - its tonal values represent the elevation of the surface, and the renderer then calculates the facing from that - while normal is faster to render - the facing has already been calculated and the x, y, z values are stored in the r, g, b colour values.

Displacement actually moves the mesh in or out, based on a height map like bump.

When a surface is viewed face on in a soft or head on light there won't be much, if any, visible difference between the three but when viewed in profile, or in an oblique light that would cast shadows from the relief, it will be obvious that the surface is smooth with bump/nomral and has real texture with displacement.

SickleYield

Mister Kitty knows.

A lot of us use bump to add "shallower" details that can be done in a 2D editor, like cloth weave or basic skin texture, and displacement for details that really require being sculpted in a 3D program, such as wrinkles or veins. Not every project really needs a sculpted displacement or normal map, but a lot can benefit from it.

I often use normal maps when I want the increase of detail I can get from sculpting in Zbrush, but not a change in an object's volume in the scene. I wish I had a dollar for every time I've had to turn off someone's skin displacement because it clipped with their clothes and the veins it was for weren't visible under clothing anyway.

Totte

You have an article about that in DS Creative Magazine issue #1: http://issuu.com/philatdsc/docs/ds_creative_01