The Invisible Map: Visual-Inertial SLAM with Fiducial Markers for
  Smartphone-based Indoor Navigation
Paul Ruvolo Ayush Chakraborty Rucha Dave Richard Li Duncan Mazza Xierui Shen Raiyan Siddique Krishna Suresh
We present a system for creating building-scale, easily navigable 3D maps
using mainstream smartphones. In our approach, we formulate the 3D-mapping
problem as an instance of Graph SLAM and infer the position of both building
landmarks (fiducial markers) and navigable paths through the environment (phone
poses). Our results demonstrate the system's ability to create accurate 3D
maps. Further, we highlight the importance of careful selection of mapping
hyperparameters and provide a novel technique for tuning these hyperparameters
to adapt our algorithm to new environments.