UDK/Ddo Lighting Problem
Hi, I am currently working on a spaceship interior in UDK. I have made all of my texture maps using Ndo2 and Ddo. I just started compiling today when i noticed a few issues with lighting. For starters my metal materials are very flat, and no matter what material i tell ddo I want, it always gives me the same shade for my Spec map. My lod resolution seems rather low, but i have my assests set to a res of 64. and the big kicker are the hard shadows, before i build my lighting my hard shadows look fine, but after, they disappear completely. I have light maps on all of my assets so i'm not really sure where im going wrong. This has been frustrating me all day. Any help or pointers would be very much appreciated.
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Glossyness = How big and soft, or small and sharp the light reflections are.
You really only need a gloss map where there is 2 different looking materials on one texture.
I think you have that mixed up. You're more likely to need a glossmap on just about anything, and will only need a specular map when you have two or more materials.
No, most models get a spec map and a constant gloss value. If there's 2 or more different looking materials on one texture, people will start to use gloss maps, and these are often lower rez because it is not as noticeable.
Here's a decent post explaining more
http://eat3d.com/forum/general-discussion/simple-description-gloss-map#comment-1019479
I'm sorry, but that is still backwards. Just because some people are still handling their textures that way, doesn't mean it's the correct way of doing things. That procedure is typical of ad-hock lighting models. If you are using a normalized specular model (which you should), then your specular map is going to represent the reflectance of the material, which for most objects is very consistent and therefor does not require texture mapping. What does vary is the texture of the surface. A good example of when you would need a specular map is when you have parts of an object that are metal and other parts which are not.
For example, take a human face. The reflectance of human skin is 0.028, and the reflectance of sweat is about 0.021 or so. That's a miniscule difference that you aren't going to be able to notice. What you DO notice is that the texture of dry skin is very rough, which causes a very diffuse specular reflection, compared to wet skin which is much smoother and therefor concentrates specular energy into a narrow reflection.
The code for the shader:
This is a basic implementation of the Cook-Torrance BRDF with Lambert diffuse, using the Blinn-Phong distribution function, the Kelemen Szirmay-Kalos geometry approximation and Schlick's fresnel approximation. It gives pretty decent results for medium rough to smooth surfaces. If you want to render rough to super rough surfaces more accurately, you could use the Beckmann distribution, the Cook-Torrance geometry factor and Oren-Nayar diffuse instead, at the cost of more instructions:
That's really not the case. The majority of modern game engines have adopted at the very least a minimal version of a physically based lighting model, which could be at the very least normalized Blinn-Phong + Fresnel. When you switch from an ad-hoc lighting model, to a physically based one, you can no longer think about your textures the same way. They are no longer arbitrary values chosen by the artist because they "look good", instead they have an actual meaning. It's a paradigm change, and if you think about "gloss maps" and "spec maps" the same way you did before, you aren't going to get good results. Physically based models allow you to more easily create plausible materials that are more robust and predictable when moved from one environment to another. If it's 2013 and you are still using a simple Phong as your lighting model, and you don't have a really good excuse, then you are simply doing things wrong.
It's much easier to make a Spec Map (Cavity, AO, Diffuse, Normal formula, etc) then it is to make a PROPER Gloss map, I mean it's just only with plugins like DDO, that recently we have access to a real-time artist kit that allows us to define material in an "on the fly" kind of way with proper masking, allowing us to lower the gap between material definition and simple constant values thrown in on the entire mesh.
And pretty much what LPStr said is true, even COD games have a basic Spec w/ Schlick fresnel formula applied to their models for the most basic assets, and alot of what you see in terms of 'good looks' required the artists to rethink their way to creating certain maps so they read much better and realistically.
The funny part is, that it's very easy to learn this stuff and doesn't require extra time other then talking with your technical artist and asking them what they're using.
That sounds totally right but it seems that you took the specular map for the glossyness/Roughness map and vice versa, or i didnt get you right
This is my point of knowledge at the moment
If I break it down its pretty simple, specular gives the brightness intensity on specific places of the reflection, works like a mask, and glossyness defines the sharpness of the reflection
The curve shows nicely what is meant by sharpness. Those are from cinema 4d, but you have them in 3Ds the same. Glossyness maps work the same as the curves, just simpler so it works only 2 ways, up or down. White to black
And if I understand right, editors take a middle value from the glossyness curve if you do not define a glossyness by a glossyness map, so most models look alright without a glossyness map and thats why they where not used that much the last decade and people use them mainly to define different materials at one texture sheet and very glossy stuff.
(I guess its different per engine which values they took as preset)
This is all for PBR though, so if you're using something like phong lighting, then you'll most likely need a specmap.
I'd recommend you to try some PBR shaders, like the one lpcstr posted in this thread, and see for yourself how roughness/glossiness affects the surface.