I think the biggest confusion is that in the past I used the glossy node with the fresnel node.
But I now it just clicked that the speculation slider is more than just the glossy node.
A plastic body simply is uniform so you set speculation to something around 0.45 and the roughness as needed. It was interesting to learn that for a diamond you need to use a speculation value of 2.4.
Question:
I have many wood textures that offer speculation and roughness maps so this transition to PBR is a little confusing
Letâs think about a wood floor that has a polyurethane coating
Specular sets the general plastic like reflection
Roughness well the smoothness of the reflection
What if the wood is however worn, areas that have no coating anymore? I feel a texture map with a high value for increased roughness would be wrong.
Wouldnât a texture map that defines vis the color the correct specularity value (is coated has no coating anymore) be still correct? The trick would be however to have a grayscale value that for plastic is read as a 0.45 numeric value in the specular slider.
With PBR the IOR or the specular value in the principled shader,should be the same,since this is a material propertie that does not change.
the roughness map on the other hand,you can add more roughness to the map if its get grunge or dirty
ect
if the wood with clear coat is worn down to the wood,then you should substract or mask the clear coat out.
remember,in the principled shader the specular (artistic IOR value) is the main Fresnel reflection.
the clear coat (a second reflection layer) is added, if you increase the clearcoat slider,to the main material with the specular.
with vis texture map you mean the diffuse albedo color map? it depents.
if the wood is coated then the IOR is differnt vs raw unpainted wood.but i think the Fresnel differents should be in maybe 1-2%.
quick search first hit says wood IOR 1.52 this is very similar to polyurthane coatings (plastics)
with painted metal that is worn or rusty on some places,then the metalness map comes into play for a differnt metal reflection on raw metal the metalness should be masked with 1.and the specular should have the paint IOR or rust IOR in this examples (ofcourse the artistic value).
yes that because the âartist friendly IOR specularâ what we have now.
as Rodger_D posted the conversation above.Cycles still uses a Fresnel calculation.the specualr gets calculated back as seen in the formular.
I think that youâre thinking of a âgloss mapâ. Thatâs basically an inverted roughness, although the mapping can be widely different for different engines (hell, roughness mapping even inside Blender isnât necessarily consistent for that matter.)
A specular map isnât like changing roughness, and itâs not like changing Fresnel. Itâs like changing the color on a glossy BSDF node.
But would a black and white texture put into the speculative slider make one area glossy and one are not glossy ?
Obviously that would work when using only slider values of 0-1
So in short just ignore specular maps and just work with roughness maps only as this defines the glossy value
And if you need to make some area reflective or not like worn wood then you mix two bags shaders via a texture map plugged into Into the factor I out of a shader mixer
To be honest,i am not 100% sure.because there are specularity maps and reflectivity maps on the site,and not sure if they are different.reflectivity would be in theory a reflection map that reflect the light percent wise(multiply).the spec map could be a glossy map,that should be inverted for the roughness input.(because on the site,there is to read glossymap>>specularity.)
you should then let the specular at 0.5 for now,and no clearcoat for now,for a test.
I have downloaded a free texture from arroway here
and builded this setup with
set every data (normal map,bump map,glossy map ect )to linear colorspace (to avoid gamma correction)
only the diffuse map should be sRGB color space
btw at the arroway texture link,there you can download easy mats for maxwell and corona render.some one with 3dsmax could make a test render to compare with blender.
if you make a texure self,then use a similar existing PBR/spec texture as basic values,maybe stencil or copy areas from ,color picking ect
or if you use the diffuse as basic then make it black and white ,and adjust the brightness contrast if its middle values,highlights and maybe dark spots are at very similar levels like the reference material,as described
if you do it like sayed, then the result should be very similar,to the material you have copy from.
depents from where the maps coming from,means if you know what the data they represent,then the workflow should be easy.
0.5 RGB is equal 0.5 slider in the glossy
0.68 V in HSV is equal 0.5 slider.
I think as long as the glossy value is not above 1.0 one can still use also gray scale to manage the reflectivity amount and still use an image map for roughness to control the roughness there.
but remember if you work with data maps,like roughnessâŚthen set the colorspace to linear or non color data(in the texture node),otherwise blender does a gamma correction to it,and we want the data how they are storedâŚlinear.
Interestingly the look of the roughness map looks better than the specular map
So it seems as long as you do not really need to clip out reflectivity (in most cases I never need to) using a texture with the roughness input as suggest does also yield better results.
