  In the presented scenario, an autonomous surface vehicle (ASV) equipped with
a laser scanner navigates on a inland pathway surrounded and crossed by
man-made structures such as bridges and locks. {GPS} receiver present on board
experiences signal loss and multipath reflections in situation when the view of
the sky is obscured by a bridge or tall buildings. In both cases, a potentially
dangerous situation is provoked as the robot has no or inaccurate positioning
data. A sensor data processing scheme is proposed where these gaps are smoothly
filled in by positioning data generated from scan matching and registration of
the laser data. This article shows preliminary results of positioning data
improvement during trials in harbor-river environment.
