ArmA 3 modeling. 3D model file extension is P3D.

ArmA 3 BIS Example Character MLOD/P3DM Model

ArmA 3 Weapon Collimator Sights Tutorial by Alwarren

ArmA 3 Custom Characters Head visible in freelook mode.

Its really strange that when you use freelook mode, you can see your custom character's head in this view if you look into sides. Default ArmA 3 bis characters do not show head in this view, nor other views.

It appears to be the ArmA 3 head (proxy?) model that shows up as its so detailed. From which LOD this comes is unknown, normally when you are in use of your character, you see View-Pilot LOD. However in my tests I removed old custom head and the HMD proxy, so where it gets the head model is unknown.