Specular /highlight spot suppression texture channel?

gnoop · Sep 19 2025

I wonder if and how much people use such thing to kill plastic look PBR often makes in something like 2d "grass bed" material or dirt. What's called specular level before, or simply specular in Unreall . We had sort of huge rise in highlight brightens a while ago like what Ultra shader setting makes in SPainter . Everything gets more shiny even with 1 roughness at grazing sun angles. I saw some mentioning in Horizon published docs . Chat GPT tells me it's a common practice . is it really so?

Eric Chadwick · Sep 19 2025

Well first of all, I would advise you to stop using ChatGPT to teach you 3d tech. It gets key points wrong while presenting them as truth, and then it takes a subject-matter expert to truly spot what is right vs. wrong in AI answers.

If you don't like the specular response, one thing is to check your roughness values, and how your mipping is changing your textures with distance and glancing angles.

gnoop · Sep 19 2025

Actually it's quite good in doing that . Suggests very well though solutions in many shaders design issues. Looks like quite well trained in the area . Makes very well working scripts and node constructs for Blender .

poopipe · Sep 20 2025

The usual specular model makes surfaces tend to perfect reflection at shallow view angles - mainly because that is actually what happens in real life, you just don't see it much because its hard to put your head close enough to the ground to see it (also atmospherics etc).

The only non-bullshit option is to apply specular occlusion - in unreal, you multiply a cavity map over the specular level texture
which i think is what you're suggesting.

in most games the specular amount is also reduced over distance/by a function of the surface normals - toksvig being the most common method. Specular occlusion is often applied alongside ambient occlusion in the renderer (screenspace AO/ GI stuff)

for rougher/absorbent surfaces using an unreal type material you can only really reduce specular level,
Using a different diffuse or specular model is really the only good way but you need to make a whole new shader for that

ZacD · Sep 20 2025

In Unreal Engine, there's composite textures that help kill specular on noisy surfaces (their reference images kinda suck, but it's great for terrain and flat surfaces):

https://dev.epicgames.com/documentation/en-us/unreal-engine/composite-texture?application_version=4.27

Valve talks about a similar problem/solution on page 28 of this presentation:

https://media.steampowered.com/apps/valve/2015/Alex_Vlachos_Advanced_VR_Rendering_GDC2015.pdf

Specular /highlight spot suppression texture channel?

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