Using Simultaneous localization and mapping (SLAM) or mapping a room (creating a 3D point cloud) or environment with Metaio Toolbox could be a solution to the challenge of using markers placed on the floor to trigger and then engage with an augment containing a 3D object modelled to scale.

point_cloud_room_mapping

Screen capture from Metaio Creator. Untextured 3D geometry placed within the point cloud of a mapped environment. Once published to a junaio channel, the 3D geometry will be placed over the environment when browsed in the junaio AR browser.