ANSWERED: About Gloss Maps!!!
polycounter lvl 6
Hi Guys, I´m trying to improve my maps knowledge and I have seen couple times Gloss Maps, but I really don´t know how to use it correctly or even how to create a nice one.I have painted 2 or 3 times on MudBox, there is a way that I could do it on Photoshop or using another map ???
Some Works I would like to use Gloss Maps
Some Works I would like to use Gloss Maps
Replies
Mental Ray and U4
Glossiness is a parameter of the specular part of your shader material.
If you consider that Specular (aka Specular reflection) is a reflection of the environment around your object where black on your spec map indicates 0 reflection and white indicates very reflective then glossiness indicates to the shader how 'broken up' or diffused the reflection is.
Objects like glass and metals will give a very glossy specular reflection where as things like say, bricks or concrete or wood will have a very diffused/spread out/ broken up low glossiness.
Dirt and dust on the surface will get in the way of the reflection and lower the glossiness level. Water and other liquids (which are very glossy) will raise the glossiness level of whatever material the suface is you can see the effects of dirt on glossiness in this image.
I couldn't find a wet/dry example of an object but these lips with matte and gloss lipstick should show what i'm talking about. note how the matte purple lips are still showing off some specular reflection, but it's blurred within an inch of it's life.
In terms of it's relation to the spec map, both are black white maps, where white means very reflective (in the spec) and glossy (in the gloss) and black means not very. You'll find though that the relationships between the two maps are different - here's an example of spec and gloss maps.
note how the wall has a fairly high amount of specular, but isn't very glossy, where as the windows arent flooded in spec, but do have a very high amount of gloss.
As JedTheKrampus rightly points out, different renderers interpret the levels of your maps in different ways so you'll have to use your eyes to ultimately finesse the shader to look right. Some other renderers (SolidAngle's Arnold) don't have a parameter named gloss, instead having a "Roughness Parameter" which, when you think about it is the same thing (both go from rough to glossy).
I saw a quick vid on from Gleb Alexander on lesterbanks.com the other day which might prove useful. It's written for blender but the concept holds up.
http://lesterbanks.com/2015/01/ways-abuse-material-roughness-blender/
Hope either this is helpful, or someone corrects my lies so I can get a better handle on it myself, I'm teaching myself shaders at the mo, so do not claim to be an expert on this.
Oskar
Thanks very much for this clean explanation, since months ago i was searching information about the gloss map and trying understand why this is useful, and how it works and you with you posted managed to explain what I didn't quite understood.
Subscribed in this thread only because of your post.
Again, a huge thanks
Oskar
On a related note, is there any particular renderer that's best if you're going to be doing your final render in Blender's Cycles engine? I've seen some discussion on that, but I don't remember if anyone reached a consensus.
Do you mean the best realtime engine to preview in?
In some PBR renders like Octane render the glossy goes in to the roughness node and also needs to be inverted.
Sorry, I wasn't very clear. In DDO, when you're setting up a project, there's options for which renderer you plan on using (I don't have it in front of me, so this is from memory. Apologies for any inaccuracies). Options include Toolbag 2, UE4, 3ds Max, Mental ray, etc.
As far as I remember, there's nothing relating to Blender or Cycles at all in there, so I'm wondering if any particular option would work better/best in Cycles.
Or am I completely misunderstanding the purpose of that option?
Ingemar Lundegren - You are absolutely correct, the purpose of DDO is map generation and the fact that you can pick and choose which maps you want for your textures, thereby saving a lot of time!
I had been inverting the glossy maps, but only just recently saw that it should be going straight into the roughness inputs. And you're right, they are labeled as Roughness in Cycles.
One way to get the feel for what the map does is to plug the glossy or specularity in to the Albedo (diffuse) in cycles. Change the gamma or brightness and see the effect on your 3D model. Then plug it back to the correct node. Is a darker tone making it more specular/shiny? If you want more specular then plug in an adjustment node and make it darker. Just an example, in reality darker might make it less specula in Cycles, i don't know but you get the idea.
The values for specularity and roughness is the same as color information. Black could be 1.0 and white 0.0 for example. Medium gray being 0.5. The maps is just a more accurate way of doing it AND can effect different areas of your UV map. If you just set a value the whole model will be affected the same way. DDO creates very detailed maps giving incredible realism. If you add dirt and grime to a texture both specular and glossy (roughness) maps will be affected very accurately and also the normal map. Add a dirt smart material and watch the result on the spec and glossy maps for example.
https://www.dropbox.com/s/khuwoqc6zxqqtm7/Cycles.jsx?dl=0
Set up your material like this for best results. This does energy conservation on the diffuse and properly feeds in the roughness map. If you want to use the Beckmann specular BRDF you'll need to remove the GGX roughness adjustment from the script, but why would you ever use anything that's not GGX?
Node setup:
You do have to square the roughness to get the right result with Cycles, as Cycles exposes the raw BRDF parameters without trying to make the roughness perceptually linear. I don't know how to bake this into the input map with the calibration script, but doing it in the shader definitely doesn't break the bank.
You can also hook up Roughness to diffuse roughness if that's what you like. It's probably a little more realistic that way, but the difference is quite small.
You might be able to speed up convergence a little with light paths, too. I'll definitely test this before I finalize the written Cycles rendering tutorial that I've been working on.
I had some problems in the past with DDO, but I will review it
I read about it, a little after making my post and you really added the explanation, Thank you !!! Despite the fact generate a map by Quixel through another map would be possible for me to get a map Gloss (at least initial? ?? as the specular of a normal map of the channel and with colors, it seems that some colorful map mode are more realistic than black & white maps
If you want to know in detail what each map does, these tutorials are a must read:
PBR Theory, by Jeff Russell
PBR in Practice, by Joe Wilson
Awesome, looking forward to that.