Usually it's used for lightmaps (example on Unity, or from polycount wiki, also on Unreal [1] [2]) . Talking about Unity, note that I'm not sure about that, maybe the detail maps are using UV2? (if a Unity user can confirm)
Hey Alec I'm working in Unity currently and wanted to try a workflow using Handplane. Specifically, Maya to Xnormal to Unity. I followed the the Maya\Xnormal video exactly and output a Maya 2013\2014 tangent map and a Unity tangent map. What displays as seamless in the Maya viewport is a different story once in Unity. I'm…
Moved your topic from Technical Talk to Unity, where you should get more eyeballs from those familiar with Unity. Have you tried looking at these solutions? https://duckduckgo.com/?q=unity+sss&ia=software