CGTalk - How light affects different surfaces

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BillSmithGH

10-29-2008, 04:52 PM

I've done some thread searches and haven't been able to find much info on this.

so... metals, plastics, rubbers, transluscent materials, stone, wood, paint, etc. etc.

I want to find as much info as possible about what specifically happens to light when it hits a particular surface, how it appears visually on that object, and how it reflects or refracts light to other objects around it.

I'm looking for super detailed information on many different types of a surfaces, like metal, for example. Not general overviews.

Any links or directions to take for this kind of information would be very much appreciated.

:)

jeremybirn

11-02-2008, 04:16 PM

Nobody answered? I guess you're asking for a big field of info. Probably the best search term I can recommend for you is "BRDF" - I won't paste google results here, but there are many papers explaining BRDF and even graphing the BRDF of specific materials. Hope this is what you're looking for?

-jeremy

BillSmithGH

11-02-2008, 04:42 PM

Awesome, thanks alot :)

playmesumch00ns

11-03-2008, 01:16 PM

Take a look in the "science of cg" thread. What actually happens is very simple: interactions fall into the categories of conductors (metals) and dielectrics (everything else), and there's quite a lot of detailed information in that thread about what's going on in each case.

What makes a particular material look 'correct' based on that is all down to micro- and milli-scale surface geometry, i.e. how 'rough' the surface is. Micro-scale is the shape of the surface at scales too small to be resolved with the human eye or a standard camera. You use brdf parameters like specular shininess to replicate this. Milli-scale is surface features that you can just about see, e.g. weaves on cloth, brush marks on steel. These features are either best replicated using the brdf or with texture maps, depending on the scale of the object in your shot.

Beyond this I'm not 100% sure of what information you're after. Have you got a specific example?

BillSmithGH

11-03-2008, 04:38 PM

thanks for the info, playmesumch00ns

I myself am still trying to narrow down what info I'm after. I'm starting a Master's project and I want to base it around realistic lighting (or as close as I can get it) set up in a game engine, (probably UT3).

So I'd like to get all this info about what is really happening with the light source and the surfaces it hits, set that scene up in Max as close as I can get it, bake it out into lightmaps or add it into diffuse, or whatever other techniques I can learn, and then get everything into the UT3 scene.

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