The Influence of Lidar Acquisition Settings on Canopy Penetration and Laser Pulse Return Characteristics

Abstract

Three airborne lidar data collections were carried out over a mixed forested and agricultural survey area within a two-hour period in July 2005. Flying altitude and beam divergence were each systematically varied in order to ascertain the relative influence of each survey parameter on the ability of laser pulses to penetrate and characterize vegetation canopy. Experimental control was maintained by varying each setting independently while keeping all other settings equal. The land covers investigated were divided into tall and short vegetation classes. Laser pulse return data for 24 tall vegetation and 18 short vegetation plots were extracted and frequency distribution metrics compared for each survey configuration. The analysis demonstrates that laser pulse penetration properties and return frequency distributions within vegetation canopy environments are sensitive to laser pulse footprint size and pulse energy concentration. These results have potentially significant implications for multitemporal lidar vegetation investigations such as lidar- based growth and yield assessment, modelling and prediction.