Estimation of aerodynamic roughness and zero plane displacement using medium density of airborne lidar data

• Main Authors: Mohd Salleh, M. R., Abdul Rahman, M. Z., Abu Bakar, M. A., Rasib, A. W., Omar, H.
• Format: Conference or Workshop Item
• Published: International Society for Photogrammetry and Remote Sensing 2016
• Subjects: G70.212-70.215 Geographic information system
• Online Access: http://eprints.utm.my/id/eprint/73058/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-84993967381&doi=10.5194%2fisprs-archives-XLII-4-W1-217-2016&partnerID=40&md5=91c3db5c78c64140a10ef3b5cf1afa87

This paper presents a framework to estimate aerodynamic roughness over specific height (zo/H) and zero plane displacement (d/H) over various landscapes in Kelantan State using airborne LiDAR data. The study begins with the filtering of airborne LiDAR, which produced ground and non-ground points. The ground points were used to generate digital terrain model (DTM) while the nonground points were used for digital surface model (DSM) generation. Canopy height model (CHM) was generated by subtracting DTM from DSM. Individual trees in the study area were delineated by applying the Inverse Watershed segmentation method on the CHM. Forest structural parameters including tree height, height to crown base (HCB) and diameter at breast height (DBH) were estimated using existing allometric equations. The airborne LiDAR data was divided into smaller areas, which correspond to the size of the zo/H and d/H maps i.e. 50 m and 100 m. For each area individual tree were reconstructed based on the tree properties, which accounts overlapping between crowns and trunks. The individual tree models were used to estimate individual tree frontal area and the total frontal area over a specific ground surface. Finally, three roughness models were used to estimate zo/H and d/H for different wind directions, which were assumed from North/South and East/West directions. The results were shows good agreements with previous studies that based on the wind tunnel experiments.