View Full Version : how to properly implement speculars maps?
01-03-2010, 07:32 AM
i'm having trouble making my shader have that solid scuffy metal look
I like the smoky hazy effect seen in the mecha girl that just recently won the cg award
here, I'm guesing he's using specular maps but when I tried it my shaders look like it's made of plastic... how do you use specular maps?
do you just use them in layers like occlusion maps or just plug them in shaders?
01-03-2010, 04:50 PM
Can you post a few pictures of the look you want to achieve?
01-04-2010, 12:11 AM
here it is
there's some part of the texture that's lambert like while some of it have that
anisotropic and if you notice at the shine at the middle arrow the shine is rough
(some parts are dark and some white) how do you do that? I'm guessing specular
but when I try it my shaderball looks like its plastic
01-04-2010, 12:52 AM
Not knowing what software you're using, here's a few things you can try...
1) Consider using reflections instead of a normal specular highlight. Start with an hdr image for your environment map, something that has some really dark areas and some areas way brighter than white.
2) Make sure to use blurry reflections on your surface, so the reflection isn't super crisp.
3) You should have some way to modulate the reflectivity of your surface in your material with a black and white map. For the map, use a grungy texture, something like this maybe...
Make sure it's very high contrast, so you have areas of full reflection and areas of no reflection.
Make sure you have a grungy diffuse map and bump map as well. That should give you pretty similar results.
If you're still having trouble, post an image of what you've attempted and maybe we can give suggestions.
01-04-2010, 12:53 AM
Oh, and here's another tutorial that may help. It's for 3dsmax, but it's got ideas that can be applied to any software.
01-04-2010, 01:18 AM
thanks, I use maya by the way, cheers :-)
01-04-2010, 01:30 AM
I think there's a bit of a tendency to try to use maps "in their original form" when such a one-step approach might be unrealistic. I suggest that you start by locating an image reference that conveys the "roughness" that you are looking for, but then proceed by applying transformations to that image which turn it into "a good input for a mathematical function."
In other words, you remove any "unwanted noise" from the image data, then re-balance it (for lack of a better term...) so that its range of usable inputs runs smoothly from 0.0 to 1.0. Or whatever. Make it "a clean signal."
Once you've got that, you can use node-based techniques to apply its influence to one or more characteristics of the base image ... reflectivity, contrast, alpha, what-have-you. You can fully control exactly what it influences, and to what degree. This really is "a digital darkroom." If there's any guiding principle here, I'd offer that it is, and always will be, "look at the light."
01-04-2010, 12:02 PM
Also remember:your spec reflections are only as good as your lighting and the environment that it's reflecting.
01-04-2010, 12:02 PM
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