New Uber: 2nd Diffuse channel?
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in The Commons
I thought I saw something about Iray Uber, in the newest update, has a 2nd Diffuse channel? how do you access that?
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Increase "Diffuse Overlay Weight" and the "Difuse Overlay Color" will appear. Set the "Diffuse Overlay Weight" image channel to an appropriate alpha map (just like cutout opacity), and the map will determine how much of the "Base Color" shows through.
Edited to add example pictures
Ooo! THAT might be useful for new thing I'm working on.
What's the use case for this versus the existing overlay techniques (LIE, Iray decal, geo shell)?
You do get the additional roughness channel as well, so it's a bit different.
One thing could be a whole bunch of textures for, say, a car, then the overlay as part of a hierarchal materials preset that applies a dirty/rusty overlay to it.
Tattoos, useable on any skin tex?
Bodypaints?
What does "Roughness" do?
AND, does this show up naturally with older shaders built on uber, or do you need to do some manipulating to get it there? (like applying the base uber and then copying settings).
Yep, appears naturally.
Thank you for posting this question -- that extra channel is interesting. I wonder what happens when it's combined w/cutout value.
This explains it better than I could.
http://blender.stackexchange.com/questions/5167/what-does-the-roughness-setting-on-a-diffuse-shader-do
Roughness and glossiness are the same thing. If you set roughness to 0, a glossiness setting would be set to 100% to get the same effect. They basically determine how shiny something is. It sets the size of the shiny circle on a flat surface. Something with roughness of 0 will have a very small shiny circle making it look very shiny whereas 60%+ will have a faded and large circle making it look duller. Specularity is how much of the circle you want to show up, almost like opacity. I believe in iRay, it's a weight channel. So you might see "Glossy Weight" which is weird because they have "Glossy Roughness", a completely self-contradictory term. There is also a "Glossy Specular" but doesn't seem to be specular at all.
So if you're confused, yeah, it's normal.
Basically, look for roughness and a weight channel associated with it. Diffuse roughness does not seem to have a weight channel associated with it which I've always found weird. I'm guessing maybe "Diffuse Weight" is it.
Roughness replicates the effect of having many extremely small bumps. If you take a perfectly reflective item and give it a bump map, then up the tiling immensely, you will see an effective 'roughness' based on how extreme the bumps are.
Real items generally have lots of these microbumps in various sense. Clothing, for example, each thread and even the individual strands of the thread are reflecting light in all sorts of directions.
Roughness (or glossiness) essentially abstracts this a bit, which is easier to compute/faster to render.
..sounds useful, but still working in 4.8 as I really don't look forward to rebuilding all my Iray skins again due to updates I heard about..
No updates...there seems to just be a new channel you can turn on if you want to or ignore.
I will say, working with it, it doesn't seem to like Black on diffuse maps much. Pic 1 just has Red in the Diffuse Overlay. Pic 2 has the label map from the prop.. the writing should just be black, but it ignores it (you can see the red and green and white wriging from the labels in there.
Trying to get the labels on with a geoshell right now.
When did this come in, I could have used this for different logo's maybe next time. Thanks for the info !