Abstract
Point density in airborne lidar surveys is one of the key parameters that influence not
only the accuracy of generated DSM/DEM but also processing and costs. Point density
variations occur (independently of keeping constant flight parameters) throughout the
survey depending on the topography, the land cover, and the laser scanning mechanism.
In this article, variations in point density across different land covers are analysed
with an airborne oscillating mirror laser scanner. A wide group of samples from the
different land covers is taken from single flight strips over level ground in order to
minimize the effect of topography. The influence of the oscillating mirror laser scanner
system is also minimized considering points along the central swath area. Mean values
for each land cover are established regarding ground point density and first pulse
returns. Significant differences in both raw points as well as on-the-ground points are
registered, mainly due to the presence of features over the ground and the degree of
opacity thereof. Regarding ground points, the relative differences between the two
software packages used are 5% approximately. Significant point density differences
can be found among the six analysed land covers. Furthermore, extrapolated pulse rate
increments are presented to fulfil lidar specifications that neglect land cover as an input
parameter to satisfy ground point density values, namely in non-overlapping areas.