Götz Echtenacher said: " I am pretty certain it is correct to adress CPs as manual tie points. They exist as well in 2D (on the images) as calculated from that in 3D."
Do you mean that CPs are treated
not as artificial Features - which as usual are projected (the 'beamer, you called it) back to near-intersection in 3D space (the 3D Tie point) then REprojected forward again to the two (or more) 2D picture planes (as 2D REprojected features?)
but as the 2D REprojected features themselves - from which an artificial Tie point is reverse-engineered?