View Full Version : Bump Maps

10-18-2005, 03:33 PM
Hi, this is prob a silly question, but how does lightwave calcualte a bump map from the following pic, Are the white bits were it stays flat and the black bits were it dips,

I just need to know if White is flat and black is the bump or if the black spaces stay flat and the white is the bit where it rises, cheers

Captain Obvious
10-18-2005, 03:54 PM
Well, with a bump map, there is no such thing as "elevation." It can't make it rise, no matter how you put it. What it does is that it changes the surface normals of the area where it goes from black to white (or vice versa), so it looks as if one is "above" the other. Whether it's the white that's raised or the black that's sinking down doesn't make one bit of difference. Here (http://freespace.virgin.net/hugo.elias/graphics/x_polybm.htm) is an explanation of it.

10-18-2005, 07:15 PM
The white portions normally *appear* higher than the black portions with default settings.

However, there's an Invert Layer button in the Texture Editor which reverses this, or you can specify a negative percentage in the Bump percentage field, or you can specify a negative Texture Amplitude for the image. Any of these reverses it.

As Captain Obvious says, bump maps provide no real geometry, just fake bumps, but it works really well in a lot of cases. A displacement map will actually raise the geometry, but the geometry has to have enough subdivisions to support the map variations. Or, model the actual bumps / grooves / whatever in modeler.


10-18-2005, 07:20 PM
He didn't ask about elevation, and if he had meant Displacement Maps, the answer is still the same.

Black is IN, White is OUT, and Mid grey is NEUTRAL. Unless you select the Invert Image checkbox.

I was going to suggest that this was an RTFM question, but then I looked in the manual.....and the Help file. Hardly anything in either of them. No explanation of how to make a bump map, nor the way values are used.