Creating a normal map from a noise map

How can I use a noise map to create a normal map?

Normal map from function?

How does it work?

You can use the “NormalFromFunction” material function but that’s a really expensive way of doing this since the noise is calculated three times.

It’s ok for testing but for production you should really look into rewriting/modifying the noise shaders to also calculate the derivatives for ‘cheap’ normals.
I just started to do so the other week but it’s not yet finished,

Hmm, I’m not really capable of re-writing my own shaders… Well, nothing complicated anyway.

I was hoping there would be an equivalent of “normal from heightmap”, or is working that out more complicated that I would hope

I see there is a normal from heightmap function Procedurals | Unreal Engine Documentation

How can I “convert” a noise map into a TextureObject2D? is that possible?

As said in my post above, the node you are looking for is called NormalFromFunction.
I also linked you to a post which shows the exact material setup…