Yes, I develop monocular slam for a stealth startup, so I have directly dealt with the requirements for markerless AR. It's a well known fact in SLAM that a ph

Yes, I develop monocular slam for a stealth startup, so I have directly dealt with the requirements for markerless AR. It's a well known fact in SLAM that a physical measurement is necessary to determine scale. IMUs get close, depth sensors are better but have rough resolution, seeing a known object (like a marker) in the space is best. Because the toy AR displays on a small 2D screen, there's a number of shortcuts that can go mostly unnoticed.