I am using 3D objects connected to a camera as a HUD. Is there a technique to anchor the objects to the corners, regardless of the resolution? (i.e., parent the objects to the camera viewport/screenspace (I'm not sure the right way to ask this) rather than directly to a camera?

What if I combine an ortho camera with a perspective camera? (I'm actually using an ortho now to render the HUD over the regular game camera).

Thank you.