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Proceedings Paper

Random forest regression modelling for forest aboveground biomass estimation using RISAT-1 PolSAR and terrestrial LiDAR data
Author(s): Rohit Mangla; Shashi Kumar; Subrata Nandy
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Paper Abstract

SAR and LiDAR remote sensing have already shown the potential of active sensors for forest parameter retrieval. SAR sensor in its fully polarimetric mode has an advantage to retrieve scattering property of different component of forest structure and LiDAR has the capability to measure structural information with very high accuracy. This study was focused on retrieval of forest aboveground biomass (AGB) using Terrestrial Laser Scanner (TLS) based point clouds and scattering property of forest vegetation obtained from decomposition modelling of RISAT-1 fully polarimetric SAR data. TLS data was acquired for 14 plots of Timli forest range, Uttarakhand, India. The forest area is dominated by Sal trees and random sampling with plot size of 0.1 ha (31.62m*31.62m) was adopted for TLS and field data collection. RISAT-1 data was processed to retrieve SAR data based variables and TLS point clouds based 3D imaging was done to retrieve LiDAR based variables. Surface scattering, double-bounce scattering, volume scattering, helix and wire scattering were the SAR based variables retrieved from polarimetric decomposition. Tree heights and stem diameters were used as LiDAR based variables retrieved from single tree vertical height and least square circle fit methods respectively. All the variables obtained for forest plots were used as an input in a machine learning based Random Forest Regression Model, which was developed in this study for forest AGB estimation. Modelled output for forest AGB showed reliable accuracy (RMSE = 27.68 t/ha) and a good coefficient of determination (0.63) was obtained through the linear regression between modelled AGB and field-estimated AGB. The sensitivity analysis showed that the model was more sensitive for the major contributed variables (stem diameter and volume scattering) and these variables were measured from two different remote sensing techniques. This study strongly recommends the integration of SAR and LiDAR data for forest AGB estimation.

Paper Details

Date Published: 5 May 2016
PDF: 11 pages
Proc. SPIE 9879, Lidar Remote Sensing for Environmental Monitoring XV, 98790Q (5 May 2016); doi: 10.1117/12.2227380
Show Author Affiliations
Rohit Mangla, Indian Institute of Technology Bombay (India)
Shashi Kumar, Indian Institute of Remote Sensing (India)
Subrata Nandy, Indian Institute of Remote Sensing (India)

Published in SPIE Proceedings Vol. 9879:
Lidar Remote Sensing for Environmental Monitoring XV
Upendra N. Singh; Nobuo Sugimoto; Achuthan Jayaraman; Mullapudi V. R. Seshasai, Editor(s)

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