Abstract
Information on rice phenological stages from Synthetic Aperture Radar (SAR) images is of prime interest for in-season monitoring. Often, prior in-situ measurements of phenology are not available. In such situations, unsupervised clustering of SAR images might help in discriminating phenological stages of a crop throughout its growing period. Among the existing unsupervised clustering techniques using full-polarimetric (FP) SAR images, the eigenvalue-eigenvector based roll-invariant scattering-type parameter, and the scattering entropy parameter are widely used in the literature. In this study, we utilize a unique target scattering-type parameter, which jointly uses the Barakat degree of polarization and the elements of the polarimetric coherency matrix. Likewise, we also utilize an equivalent parameter proposed for compact-polarimetric (CP) SAR data. These scattering-type parameters are analogous to the Cloude-Pottier’s parameter for FP SAR data and the ellipticity parameter for CP SAR data. Besides this, we also introduce new clustering schemes for both FP and CP SAR data for segmenting diverse scattering mechanisms across the phenological stages of rice. In this study, we use the RADARSAT-2 FP and simulated CP SAR data acquired over the Indian test site of Vijayawada under the Joint Experiment for Crop Assessment and Monitoring (JECAM) initiative. The temporal analysis of the scattering-type parameters and the new clustering schemes help us to investigate detailed scattering characteristics from rice across its phenological stages.
Highlights
14 One of the primary parameters associated with the changes in the Synthetic Aperture Radar (SAR)15 backscatter coefficient is the crop canopy distribution at each phenological stage
189 we present the newly proposed scattering-type parameters for both full- and compact-pol SAR data (Dey et al, 2020) for monitoring rice crop
Full-polarimetry In FP SAR, the 2 × 2 complex scattering matrix S encompasses complete polarimetric information about backscattering from targets for each pixel. It is expressed in the backscatter alignment (BSA) convention in the linear horizontal (H) and linear vertical (V) polarization basis as
Summary
14 One of the primary parameters associated with the changes in the SAR15 backscatter coefficient is the crop canopy distribution (e.g., tillers, leaves, and16 panicles) at each phenological stage. 14 One of the primary parameters associated with the changes in the SAR. 15 backscatter coefficient is the crop canopy distribution This distribution in the crop 17 fields leads to randomness in scattering (Yuzugullu et al, 2015). 18 situations, polarimetric entropy (H) is an important parameter to quantify. In Cloude and Pottier (1997), an unsupervised classification. 20 scheme (H/α) was proposed using H and the average scattering-type param-. The H/α plane is sub-divided into nine zones to suitably cluster.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: ISPRS Journal of Photogrammetry and Remote Sensing
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
