An approach to estimate tree height using PolInSAR data constructed by the Sentinel-1 dual-pol SAR data and RVoG model

Abstract

We estimate tree heights using polarimetric interferometric synthetic aperture radar (PolInSAR) data constructed by the dual-polarization (dual-pol) SAR data and random volume over the ground (RVoG) model. Considering the Sentinel-1 SAR dual-pol (SVV, vertically transmitted and vertically received and SVH, vertically transmitted and horizontally received) configuration, one notes that SHH, the horizontally transmitted and horizontally received scattering element, is unavailable. The SHH data were constructed using the SVH data, and polarimetric SAR (PolSAR) data were obtained. The proposed approach was first verified in simulation with satisfactory results. It was next applied to construct PolInSAR data by a pair of dual-pol Sentinel-1A data at Duke Forest, North Carolina, USA. According to local observations and forest descriptions, the range of estimated tree heights was overall reasonable. Comparing the heights with the ICESat-2 tree heights at 23 sampling locations, relative errors of 5 points were within ±30 ​%. Errors of 8 points ranged from 30 ​% to 40 ​%, but errors of the remaining 10 points were >40 ​%. The results should be encouraged as error reduction is possible. For instance, the construction of PolSAR data should not be limited to using SVH, and a combination of SVH and SVV should be explored. Also, an ensemble of tree heights derived from multiple PolInSAR data can be considered since tree heights do not vary much with time frame in months or one season.

Keywords

• Constructed polarimetric SAR data
• Dual polarization Sentinel-1 SAR data
• Polarimetric interferometric SAR
• Random volume over the ground model
• Tree height estimation