I created a very simple tool in Substance Designer to generate High-Frequency Bump maps (actually height maps, but those are interchangeable) from Normal maps.
It’s an .sbsar file.

Download Here

How to use it:

You can use it with Substance Player. It’s a great tool, fast and free. 🙂

Why do you need something like this:

In many cases, you have assets where the Normal map is trying to replicate the look of a displaced/subdivided surface, hence you can’t use them together (you don’t want to modify the surface normals the same way twice).

In game engines usually, you don’t use subdivisions and displacements so there is no issue there. But this is not true for any situation where you have displacement/subdivision or high res geo.

For high-quality assets (not in game engines) you need both (displacement or high res geo and high-frequency detail bump/normal maps as well).
High-frequency details as bump/normal maps because you already have almost everything from the displacement/subdiv or high res geo part.

It’s almost like an Autobump feature, but with more control (in that case always without any Normal/Bump map).

This idea is not new of course. Also, we used a similar tool at the studio for years, created by Kristof Lovas. Thanks, mate. 🙂

The header image is rendered at subdiv level 4 with a high-frequency bump map as well (converted from the Normal map).

One more thing

If you really want to use your original Normal map (usually I don’t recommend it), you can mix that with the Hight Frequency Bump map (Maya, Arnold example):

• Use an aiNormalMap node for the original Normal map.
• Use a bump2d or an aiBump2d node for the HF Bump map.
• Than connect them: bump2d out value to the aiNormalMap Normal input.
• Connect the aiNormalMap Out Value into the shader (Normal Camera).
• Change both intensity as you see fit.

Cheers, D