VOXEL-BASED ESTIMATION OF PLANT AREA DENSITY FROM AIRBORNE LASER SCANNER DATA
- Graduate School of Global Environment Studies, Kyoto University, Kyoto, 606-8501, Japan
Keywords: Canopy structure, Three-dimensional (3-D), Flight line, Lidar, Plant area index, Crown volume
Abstract. Three-dimensional distribution of plant area density (PAD) was retrieved using airborne laser scanning (ALS) data. The calculation of PAD requires the number of laser-pulses intercepted by plant materials and which are not intercepted by trees (i.e., passed laser-pulses) for the spatial unit. To estimate the passed laser-pulses at a voxel (1-m voxel in this study), we traced every laser-return by using its flight line information. The assumption was that every laser-pulse traveled on the orthogonal line to flight line, meaning that the sensor mounted in the aircraft scanned perpendicularly to its flight line. Our function based on this assumption allowed PAD to be calculated. Consequently, we successfully obtained the PAD profiles at every 1-m voxel for the canopy area of 56 trees, which could be useful in the quantitative assessment of canopy structure at a broad scale.