RM Basic Shader

How to work correctly with one input map and with RMs Material Collection.

Part 1: Building structure like RM

1: InPut Map: Bitmap, Noise or some other generator

It's the diffuse map (full colour) nothing interesting. Mainly in Real-World size Coordinates, Seamless. Sometimes need adjusting in scale.

2: Main Color Correct: ColorCorrect (but we can add everything we want for the diffuse) 

Everybody loves Color Correcting so it's needed and we have it. :)

3: Grayscale: ColorCorrect.

Now i'm converting the InPut map to Grayscale with colorcorrect set to monochrome (or reduce saturation to -100). Nothing more.

4: Define Blacks and Whites: Output

Now i scale the grayscaled map to pure black and pure white

This is how its made:Enable Color Map; Add new point for the Blacks(Red point) and new for the Whites(Blue point). Move the red point until i define Pure Black (0,0,0) and then move the blue point until i define Pure White (255.255.255).

NB: If you use only the starting points and moving them to negative or over 1 values you can define Pure Black and White but only for the preview because we use 32bit material editor and renderer in the end all will be broken.

5: Bump Height: VrayColorToBump

Because i've defined Pure Black and White and in VrayMtl changed the bump map weight to 100% so value in this node is working correctly. We need to use this setup in case we are using some other color manipulation like Composite, mix and etc. and it's easy to setup.

6: Reflect Map: Output

Here i define the imperfections in the reflectance of the shader. Points of the output corresponds to percentage based on IOR Reflectance. (like if IOR gives 50% Reflect at some angle we will reduce it by factor)

Because I have Pure Black and White points corresponds like we have color in the slot on VrayMtl if it's 0 so it's like we have black (0.0.0) no reflect, if its on 1 its 100% based on IOR Reflectance, if it's on 0.5 it's like we have mid gray (128.128.128) so 50% based on IOR Reflectance and etc. Higher values more reflective (we can go over 1 but it's not physically accurate)

7: Glossiness: Output (this is the hard part)

Now I will define the glossiness of the material. I have Pure Black and Pure White so points on the Output will correspond to value in the Glossiness spinner.

In this case i've put the right point on 0.65 (whites) and left point on 0.85 (blacks) (i know i've inverted the map), where was the white now we have colour value that correspond to glossiness 0.65...

... same goes to the blacks where i've defined to be like 0.85 glossiness.

End of the part 1 for the maps... now on...

Part 2: VrayMtl (and why i suck at setting this and claiming it's not Physically accurate)

Only thing we need to specify is IOR and Bumpmap weight to be at 100%

Some reference IOR's

Water 1.33

Glass 1.52-1.62

Acrylate 1.51

Melanine 1.79

PolyCarbonate (plastic) 1.61

Vynil 1.53

rock, sand etc. ~1.42,

wax 1.48

and any other you can find on the net. But if you leave it on default 1.6 will be good enough.

Bad Practice: Why my material doesn't reflect like need to be let rise the IOR... nope check if the map in reflect have pure white if it has gray sorry no physical accurate reflectance based on IOR... (i've saw a lot materials where IOR is set to 2.2 and it has gray color in the slot, no point to have two values defining one effect) You need to rise IOR over the physical values only if you need to cheat something, or having grayish map in slot.

Bump must be 100% if we are using VrayColorToBump

Part 3: But i need to change the Texture and shader doesn't look like the original, what to do... (or how to modify this setup)

Simple answer: Look at Part 1, point 4. If you fix only this Output the shader will be the same... will have same reflect, bump and glossiness like with the original texture.

All shaders in my collection will be setuped by this. You can modify it at 3 places(global, only grayscale channel and per shader node) add Composites, mixes, RGB tints, noises end etc.

Happy shading and do it right.

Just a hint what and how, not mandatory to use, other methods are working too. Those are mine practices developed over 10y experience, before Bertrand and Other internet stars published them in blogs and forums. I hope to never see again shaders with ior 2.2 and reflect with gray... and quotes like "yah, but it's not universal"

Best Regards

Rostislav M.

Version 1.0