Specular aliasing and Normal to Roughness

On the 4.14 release page, it says that specular aliasing can be mitigated with use of a “Normal to Roughness” feature. Where is this feature? How do I use it? Google isn’t turning up anything useful when I search for “Normal to Roughness UE4”, etc.

If anybody could point me in the right direction, I’d be grateful :slight_smile:


Here you go, this pdf from valve has some basic info.

Thanks for the info!

Valve mentions a solution for specular aliasing as:

But the release announcement for 4.14 makes it seem like a solution has already been implemented by Epic, with:

So am I reading into that more than I should be?

There’s multiple tricks to reduce aliasing, the shader one probably hasn’t been implemented in UE4, but the Normal To Roughness has. Basically all you need to do is have a normal map and a roughness map, and UE4 will automatically generate the mip-maps for both to reduce specular aliasing when viewed from a far distance and/or if the normal map has very sharp or bumpy details. It’s kinda like precomputed anti-aliasing that maintains correct roughness.