Abstract
When estimating the slope and aspect of a natural surface obtained by bathymetric Lidar scanning, discrepancies in the elevation data from neighbouring strips often cause artefacts. In this paper, a novel algorithm for slope estimation avoiding this kind of artefacts is presented. The algorithm is based on filtering the point data in the region of overlap using a set of scan angle based thresholds. Each threshold yields a data set with different selection of points from the neighbouring strips. Gradient estimates based on these data sets are then combined by either averaging or applying a trimmed mean type operation to obtain the artefact-free slope estimate. The algorithm is developed using bathymetric Lidar data and the obtained slope estimate of the seabed is used for the correction of the Lidar waveform data. The developed method is applicable in a wide range of situations where overlapping data from different sources need to be combined.