#glossiness

MetallicRoughess VS Specular Glossiness

Source

Metal Rough Worfkow

Base Color Raw color with no lighting information. Small amount of ambient occlusion can be baked in if using it for micro-surface occlusion. The color range for dark values should stay within 30-50 RGB. Never have dark values below 30 RGB. The brightest color value should not go above 240 RGB.

Roughness Describes the microsurface of the object. White 1.0 is rough and black 0.0 is smooth. The microsurface if rough can cause the light rays to scatter and make the highlight appear dimmer and more broad. The same amount of light energy is reflected going out as coming into the surface. This map has the most artistic freedom. There is no wrong answers here. This map gives the asset the most character as it truly describes the surface e.g. scratches, fingerprints, smudges, grime etc.

Normal Normal map

Metallic Tells the shader if something is metal or not. Raw Metal = 1.0 white and non metal = 0.0 black. There can be transitional gray values that indicate something covering the raw metal such as dirt.

* With metal/rough, the areas indicated as metal in the metallic map have a corresponding metal reflectance value in the base color map. The metal reflectance value in the base color needs to be a measured real-world value. Transitional areas in the metal map (not raw metal 1.0 white) need to have the metal reflectance value lowered to indicate that its reflectance value is not raw metal.  

Also, with metal/rough, you only have control over metal reflectance values. The dielectric values are set to 0.04 or 4% which is most dielectric materials. The dielectric is hard-coded by the shader and you don't need to set it in Substance. Some shaders add a specular control that allows you to change the fresnel reflectance value at 0 degrees.

Specular Glossiness Workflow

Diffuse Raw color with no lighting information. Small amount of ambient occlusion can be baked in if using it for micro-surface occlusion. The color range for dark values should stay within 30-50 RGB. Never have dark values below 30 RGB. The brightest color value should not go above 240 RGB.

Glossiness This map is the inverse of the roughness map. White 1.0 is smooth and 0.0 black is rough.  Describes the microsurface of the object. The microsurface if rough can cause the light rays to scatter and make the highlight appear dimmer and more broad. The same amount of light energy is reflected going out as coming into the surface. This map has the most artistic freedom. There is no wrong answers here. This map gives the asset the most character as it truly describes the surface e.g. scratches, fingerprints, smudges, grime etc.

Specular This map contains the reflectance information for both metal and dielectrics (non metal) surfaces. This is a key difference in the metal/rough and spec/gloss workflows. The same rules apply. You need to use measured values for metals and most all dielectrics will fall with the 0.04 - 4% range. If there is dirt on the metal, the reflectance value needs to be lowered as well. However, you can add different values in the specular map for dielectric materials since you have control to author the map.

There isn’t much information about the specular map in the Sims 4 CC community. Honestly, it is one of the very confusing and frustrating parts to deal with. So I decided to investigate further.

I created a box with a uniform texture grey texture, but with a varying specular map. Each side of the box was given a unique specular color with a linear opacity gradient. Furthermore, the sides were numbered in the texture making it possible to analyze in-game.

I tested the following colors. UV-map and numbering laid over the specular map for info. Top-left image (number 1) is face down in-game. I had to turn the box and make 3 test boxes in total to see the red as well.

I think the result speaks for itself. I took one picture with boxes in the sun and all sides visible.

The effect of the different channels is beautifully described here, where a very similar experiment is performed. To sum up:

Red - sharpness (blurry at 0, sharp at 255), green - reflection, blue- falloff, alpha - strength. A completely non-reflective diffuse surface has a specular map with the color (0, 0, 0, 0).