How is the HUD Generated?

So this goes for both the imagery generated by the Shooting Glasses/Tactical eye pieces employed by Marines but how the hell do MJOLNIR Helmets generate a HUD? Is it holo-projectors inside the helmet? I’m very confused.

Either tiny projectors displays the hud on the inside of the visor like a refined version of modern fighter pilot helmets or the glass of the visor are high tech and display the HUD itself. Probably the later considering ODST helmets visors have a digital effect when they polarize and depolarize.

The ‘HUD’ description isn’t really accurate in the case of MJOLNIR. I’m pretty sure it’s closer to a helmet/head-mounted display, with the interior of the helmet having a screen that displays visuals from various cameras and sensors on the exterior, which then has additional information (such as shield status, motion tracker, etc.) overlaid.