Paper Info
Title
Compact Polarimetric Response of Rape (Brassica napus L.) at C-Band: Analysis and Growth Parameters Inversion.
Abstract
Growth parameters like biomass, leaf area index ( LAI) and stem height play an import role for crop monitoring and yield prediction. Compact polarimetric (CP) SAR has shown great potential and similar performance to fully-polarimetric (FP) SAR in crop mapping and phenology retrieval, but its potential in growth parameters inversion has not been fully explored. In this paper, a time series of images of CP SAR was simulated from five FP SAR data gathered during the entire growth season of rape. CP response of 27 parameters, relying on Stokes parameters and their child parameters, decomposition parameters and backscattering coefficients, were extracted and investigated as a function of days after sowing (DAS) during the whole rape growth cycle to interpret their sensitivity to each growth parameter. Then, random forest (RF) was chosen as an automatic approach for the growth parameters inversion method, and its results were compared with traditional single-parameter regression models. Most of the CP parameters showed high sensitivity with growth parameters and great potential for growth parameters inversion. Among all of the regression models, the quadratic regression model showed the best performance for all of the growth parameters inversion, the best result for biomass inversion was the third component of the Stokes parameters (g3) with R-2 of 0.765 and RMSE of 73.20 g/m(2). For LAI and stem height was one of the Stokes child parameters, the circular polarization ratio (U-c), with R-2 of 0.857 and 0.923 and RMSE of 0.66 and 18.71 cm, respectively. RF showed the highest accuracy and smallest RMSE for all of three growth parameters inversion; R-2 for biomass, LAI and stem height were 0.93, 0.96 and 0.95, respectively; RMSE were 46.24 g/m(2), 0.25 and 13.5 cm, respectively. However, there are also some CP parameters, which showed low sensitivity to growth parameters, that had high importance for RF inversion. The results confirmed the potential of CP data and the RF method in growth parameters inversion, but they also confirmed that it was difficult to give a physical interpretation for the RF inversion model.
Year
DOI
Venue
2017
10.3390/rs9060591
REMOTE SENSING
Keywords
Field
DocType
compact polarimetric (CP) SAR,rape,Radarsat-2,day after sowing (DAS),random forest,Stokes parameters,polarimetric decomposition,backscatter coefficients
Leaf area index,Stokes parameters,Regression analysis,Inversion (meteorology),Backscatter,Remote sensing,Polynomial regression,Mean squared error,Geology,Inverse transform sampling
Journal
Volume
Issue
Citations 
9
6
3
PageRank 
References 
Authors
0.43
17
7
Name
Order
Citations
PageRank
Wangfei Zhang152.86
Zengyuan Li25825.14
Erxue Chen33617.10
Yahong Zhang430.43
Hao Yang5287.63
Lei Zhao6194.83
Yongjie Ji741.49