/3/ - 3DCG

This is my first time trying to create a high-quality game asset using normal maps.

I'm a bit confused about one thing, though:

To create perfectly circular extrusions on the highpoly mesh, I make a simple octagonal shape, knowing that, when I smooth it, it will come out perfectly circular.

Pictured is the low-poly mesh, featuring some octagonal extrusions which are perfectly cylindrical in the highpoly version.

However, it seems that baking the "perfectly circular" look to these octagonal extrusions is not working as well as I'd hoped. Am I overestimating the ability of normal maps to make these extrusions look circular on the low-poly model? Or am I missing something?

Currently the only thing I can think of to alleviate this is to add more resolution to the low-poly model, but I don't want to do that unless absolutely necessary.