II. RELATED WORK
Davies et al. [3] details the design and implementation of
a Virtual Time Window (VTW) system that facilitates on-site,
mobile exploration of heritage sites with a tablet running a virtual
world viewer connected wirelessly to an OpenSim server
on which the virtual reconstruction of the Cathedral is hosted
(see Fig 6). The system uses GPS data to facilitate location
tracking as well as sensors (accelerometer and magnetometer)
to synchronise the user’s position in the real world with the
avatar’s position in the virtual environment, without the need
for explicit interaction (i.e. using input devices) on the part of the user, thus providing a solution to the vacancy problem
while keeping cognitive load to a minimum.