The challenges of indoor environments and specification on some alternative positioning systems

This paper gives an overview of the current and near future positioning capabilities for indoor environments with focus on the research activities in that field at the Institute of Geodesy and Photogrammetry at the ETH Zurich. Object of study are those novel indoor-position systems that have the potential to achieve cm-level accuracy or better which is seen as a requirement for most geodetic applications. The focus is given on four alternative positioning systems where the GeomETH group at the ETH Zurich has made some experiences. These systems are iGPS, which is a system based on a rotating infrared laser fan, the Locata system that uses GNSS similar signals on pseudolites, the cricket ultra-sound system and a photogrammetric laser beam positioning systems (CLIPS) that is currently under development. As a result it can be noted that there are several unconventional positioning systems on their way that may compensate for the deficiencies of GNSS or total stations.