moony
May 27, 2024, 9:25am
72
MartinZ:
I mean like is it different if those are pill shaped details, or maybe diamond shaped, or maybe cubes, or maybe irregular crystal like stuff, or maybe Suzanne heads.
Isn’t this similar to the discussion we had over on the microroughness thread a few years ago.
The experiments you and I did suggested that the geometry of the microsurface does indeed affect the overall result (at least in terms of microroughness falloff which is what we were concerned with at that time). It makes sense that other properties might also be affected, like anisotropy etc depending on the underlying geometry of the microsurface.
A simple demonstration like the one in Thea tutorials, I use waves instead of bumps just to make it more uniform so we can see better. Same bumps, different height. Very different falloff. The effect can start anywhere (at any angle) and reach it’s highest point anywhere as well. The intensity can be different on each end of the viewing angle range as well. I am not making any assumptions of how it is in reality, but this could easily be so - we don’t know about any definite tendencies of format…
Inspired by MartinZ’s wave test - I have created my own scene to try out different surface shapes and sizes. Images are blurred intentionally as I was getting some moire patters. I used the inbuilt wave texture and micro-displacement to create the geometry. I used an RGB curve node to modify the surface shape and a math node to change the height.
These are the surface types I have tested so far:
A sine wave
Flattened sine wave (same height as 1)
Sharpened sine wave (same height as 1)
Sine …
I think I understand - and I did such a test on the Disney thread - adding a very small bump map to simulate the microsurface (see below). This would be an ideal scenario - since all you would need to do to simulate any surface is plug an appropriate bump or normal map into a perfectly glossy shader.
The problem is - Blender doesn’t handle textures with a very small scale very well at all and you can start to get all sorts of image artifacts if you scale the texture down too much.
One thing …
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