Smoke Residues Shading Question,Diffuse, Please Help
polycounter lvl 10
Hi there guys, I am having a rare time with the industrial chimeney, mostly the smoke residues effects on the materials, metal,brick. Specifically the smoke effect on the brick, as i haven't find any good reference that can prove if my shading tests are going in the right way. Mostly what I can say is that the brick gets "burned" by the smoke. I am trying to replicate the same effect, as on this picture with the burn and dodge tools in photoshop:
What I am not sure about is that if the smoke can produce that tone elevation like in the red color, naturally produced by the Burn tool, of this image: 
What I am trying to replicate is a very old chimeney:\ but doing the best to keep it real. Here is my diffuse map: 
Please guys help me :P
cheers!
What I am not sure about is that if the smoke can produce that tone elevation like in the red color, naturally produced by the Burn tool, of this image: What I am trying to replicate is a very old chimeney:\ but doing the best to keep it real. Here is my diffuse map: Please guys help me :P
cheers!
Replies
That's a really good thread to stop in and ask material/texture questions like this. For future reference
As for the material at the moment, i think the diffuse is looking good. Well. Aside from the left half being clearly blurred/blended and being very salmony, But I'll go ahead and assume that's intentional and get to the smoke:
Charcoal, Soot, ash, etc doesn't have a whole lot of character in the diffuse ( I know someone will prove me wrong, But really. Its pretty much all black/charcoal grey). Where i see a problem with your material is your soot or residue is specular, and quite glossy for such a diffuse surface. Diffuse meaning it scatters all the rays of light that hit it, And reflects back few to none, resulting in no or very broad specular highlight. My point being, i would focus on the specular to really set apart these two materials. Some soot, or ash has a kind of "sparkle" to it and has little flakes of reflective material. I don't think this is the case in your soot, but it might be worth adding a plash of speckle to the spec map just to give it some interest. The brick at the moment is quite glossy as well for being exposed to weather, and the elements, Being outside, Being an exhaust pipe, etc. I really like the right side of the texture so far, And how the pink brick pops out of the black soot from time to time. That's looking pretty nice.
If you could get a consistency from right to left with the rest of the texture following suit, i think the diffuse will be looking pretty good. Then Work on your spec and gloss map if this project calls for one.
Edit: To clarify: It isn't the quality of the soot itself that will add interest and realism to your diffuse, But how it interacts with the brick. Soot itself, Smoothed out into a pile has little diffuse character. It will have bump, and quite a bit of lighting character, But the diffuse will have little. The key to getting this right i think is make sure the interaction between the pink brick and the soot looks nice (and you have a good start) and getting the specularity right.
Hope that helps a bit :poly142:
Did a Brcik Mask so the smoke effect spec is not that high
I think if you can visibly see the highlight on the soot, its too glossy and too specular. I realized i didn't explain very well what exactly spec, Gloss, and all that does and how they work together. So let me try to explain:
The way you go about changing the specular exponent can been done in a few common ways that i know of.
1. A gloss map. I believe this is reserved to grey scale, unlike a specular map. What it does is tells different parts of the texture how high or low the exponent should be. black being a very broad highlight and lower exponent, and white being very glossy and high exponent. Greys again are everything in between. You want to keep gloss maps fairly simple from what i hear, Because you can get some strange result if you over complicate them. Depending on what your rendering in it will depend how you apply a gloss map. In udk you can plug in the gloss map multiplied by X constant and plugged into the specular power node for the material. The X will be adjust to a happy level to suit whatever material your working on.
Though gloss maps do what they do well, They aren't used in games much (from what i understand, Correct me if I'm wrong). I can't speak to whether or not this is how all games separate materials exponents, But its the only other way i know of:
2. Using a mask, or alpha. You can make a black and white image in your alpha channel in the diffuse, and make the smokey areas white, and make the brick black. Again, you want masks to be fairly simple. You wont want to duplicate the diffuse and make it grey scale. You'll like want to black out the entire alpha, Then select the soot (Ctrl+click the layer thumbnail) then paint pure white on the alpha. Depending on what you need to acheive, you material will vary. But you'll use this alpha to separate the soot (or whatever material) from the brick (or whatever other material).
Now the thing with your materials is that they are pretty similar, in real life. as far as specularity and exponent. So i'd image you can get away with not using a gloss map or a mask to separate the materials.
http://www.gcmobilesodablasting.com/wp-content/uploads/2012/02/0062.jpg
you can see in that image, The brick is pretty matte (it doesn't reflect a lot of light, and doesn't have a bright specular highlight) And it doesn't have a small or sharp highlight. The light is scattered across the surface in a very wide fashion (Meaning the exponent is very low)
The reason i try to explain this is becuase its easier to create materials once you understand what makes them they way they are. Which I'm still very much learning, So take everything here with a grain of salt. Maybe one of the real pros will drop in and learn us both something