ACCURACY IMPROVEMENT OF A IMMS IN AN URBAN SCENARIO

Abstract. Indoor Mobile Mapping Systems (IMMSs) technologies are becoming increasingly popular thanks to the possibility of acquiring a massive amount 3D data in fast and effective way those areas where GNSS signal is unavailable, like urban canyons, densely vegetated areas, underground sites buildings. They offer an efficient produce point clouds but with noticeably lower accuracy than traditional Terrestrial Laser Scanning (TLS). The present paper wants analyse two different methods improve cloud coming from IMMS survey vast scenario. first approach uses points collected during RTK as Ground Control Points (GCPs). second one involves TLS static scans Scans (GCSs). Both these procedures allow us introduce constraints before generating rigid final cloud. tested Backpack Heron MS Twin Color, produced by Gexcel S.r.l. instrument was acquisition historical centre Meda (MB) northern part Italy. Results show that between constraints, maximum error residuals on checkpoints some decimetres. has allowed quickly area not otherwise obtainable techniques. developed proved be essential for proper reconstruction environment.