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View Full Version : What is a normal map?



adrian
09-25-2003, 11:05 AM
Hi,

What is "normal mapping" and why do you use it? There's a tut on simplylightwave.com but being on a 56k dialup (and automatically disconnected after 2 hours) I can't download it.

I viewed the avi but I'm like "doh... ok - so what?"

Is it like UV mapping?

Adrian.

Mylenium
09-25-2003, 12:58 PM
Normal mapping has only little to do with normal texture mapping. It's some sort of combining displacement and bump mapping compensating the weaknesses of each method. The key point is that you have a hi-res mesh and can bake geometric info into a multi colored or b/w image which then can be applied to a lo-res mesh. This is done by comparing the differences between the lo-res and hi-res meshes. You can then take your normal map and aplly it to your lo-res object to add details. So far this sounds much like good old bump maps. The trick now is to invoke special rendering routines (In case of LW a Shader) that interpret the image. In addition to normal bump maps this also conatins info on in which direction polygons' normals where facing at the time the map was made. At this point it will become more like displacement mapping but without the overhead - you do not need to create millions of extra polygons to see correct shadows and reflection (which you don't get with normal bump mapping). This technique was first mainly used in games where it is important to have few polygons but still much detail but there are also uses for "serious" animation. You could for instance have a crowd scene with thousands of people and use normal mapping on low polygon dummies in the background and still maintain the illusion of detail.

Hope this helped a bit.

Mylenium