[Mattia Sullini]

While setting up my mats today i have realized that enabling the map for the roughness channel doesn't disable the control in percentage. Maybe this happened before, either, but i guess i remember that enabling maps would make the value box become grayed...
Just wondered if this is a bug or not...even because i cannot figure out the precise way in which the two controls interact one with each other...

[Pierre Caron]

It seems that the numeric value defines the roughness value of the white pixels in your map.

[Mattia Sullini]

To me is a bug, since the percentual value seem to act as a multiplier for the values in the map, meaning: value 50%, pixel value 50%, result 0,5x0,5=0,25 (25%). If the behavior is this, means that results are predictable only for extremes' values (1x1=1, 1x0=0, 0x1=0, 0x0=0...). I guess i am right since the results are predictable only when the Lambertian checkbox is on (1x multiplier).
this is definitively a bug...but could become something interesting if there would be the possibility to use the map in additive mode...this way i would not need to create a second BSDF layer for reflections (typically i use 2BSDF, one lambertian or almost, for the main color, and another one for specularities...)

[hyltom]

I think the bump map is here to define some zone of roughness, not some intensity...Personaly i understand it like that...maybe i'm wrong.

[Mihai]

It's not a bug, it's like Pierre Caron said, when you use a roughness map, the percentage acts like an upper limit for your roughness map.

This lets you change the material quicker and more exact how rough a surface should look without having to update the map. It also lets you use the same map in different bsdfs, which can have different roughness values.

[Mattia Sullini]

Uhmmmm....and what if the lowest value in the map is higher than the specified value? I can be wrong but to me seems that in this case the overall roughness is decreased, meaning that it has something to do with the black, as well....
For example: I have a grey 188 map, ok? Then i set the value to lambertian: in this case the result is compatible with a 50% rough surface. But if i set the value to 0% i get a mirror surface, meaning that the value makes the roughness drop to 0%.
The effect should be then similar to a multiplier, rather than a roughness "gamma" control...and is not that predictible, to me.
If the aim is to allow users to use a single map in several BSDF, wouldn't be better to add a brightness&contrast control in texture viewer? (and a lot of RAM on my computer, as well )

[Pierre Caron]

It's just working another way but it's very efficient.
Keep in mind that the value is the maximum roughness value applied and that the pixel values in your map act as a percentage of this max value.
Let's say you set roughness value to 50. A RGB 255 255 255 in your map will give you a roughness value of 50 (50x100%) and a grey 128 (50% of 256) will give a roughness of 25 (50% of your 50).

[Mattia Sullini]

Ok, i understand...But, even if i agree this "feature" gives you onthego editing capabilities, they are still incomplete and require quite some imagination to predict the effects. I do not find this suitable for a definitive product, it looks much more like a trick, rather than a feature. Meaning: even if i can tighten a screw with the top of a knife, it would be better to have a screwdriver, right?
BTW, thanks for feedback, Mihai and Pierre

[Mihai]

Well it's more of a convenience feature, if you're looking for absolute accuracy, then ofcourse you'd be better off just editing your texture in Photoshop. This is more of a "could use a little bit less/more", so you don't have to edit the texture, you just lower the roughness value a bit.

[Fernando Tella]

I guess what Mattia is trying to say is that it could be more predictable if something like "Texture brightness" appears beside or under the roughness square when there is a texture working instead of just a number which you have to guess what it does.

[Mattia Sullini]

Something like that, Fernando. maybe a "brighter/darker" or "increase/decrease overall roughness".
What i am trying to explain with my poor english, is that this way of controlling roughness is "asymmetrical"...since 100% means "map as it is", and since every possible value must be lower than 100%, i can only darken the map, right? Why not to make possible to brighten it?
And since these settings concern the map, i would find natural to look for them in the texture viewer, right beside the "invert" checkbox.

[Fernando Tella]

Which leads us to ask for some color correction controls (brightness, contrast, saturation, hue) at the texture picker.

[Mattia Sullini]

Aaaaabsolutely!

[hyltom]

I really don't understand where is your problem here. Forget the roughness and take for example the bump control. If i follow you, when i create a bump map, i should take care of it's color intensity to control my bump value( i can not imagine what the map will look like if i want to have a 1% bump value)...that's a crazy idea. How many time should i edit my image in order to satisfy my requet? Personaly, i prefer to create my map that will defined how the bump or the roughness should look but keep the percentage as a control of its intensity.

[Mattia Sullini]

For what bump is concerned i agree with you, since the results depends on the difference between pixels, rather than their absolute value. With roughness in MW the things work in a very different way. The percentual value doesn't control the intensity of speculars (as if it was a weight control), it affects the roughness, that is really different. If i apply a 100% value to a map, what i get is exactly what i expected to get creating that map. Lowering this value makes the map darker, meaning that you affect material's roughness. So, lower values mean crisper (and not weaker) reflections. I would find it useful if it was a way of controlling speculars intensity, but is not so!