Moving Towards L-Band NASA-ISRO SAR Mission (NISAR) Dense Time Series:
Multi-Polarization Object-Based Wetland Classification in Yucatan Lake,
Louisiana
Abstract
Given the key role, wetlands play in climate regulation and shoreline
stabilization, identifying their spatial distribution is essential for
the management, restoration, and protection of these invaluable
ecosystems. The increasing availability of high spatial and temporal
resolution optical and synthetic aperture radar (SAR) remote sensing
data coupled with advanced machine learning techniques have provided an
unprecedented opportunity for mapping complex wetlands ecosystems. A
recent partnership between the National Aeronautics and Space
Administration (NASA) and the Indian Space Research Organization (ISRO)
resulted in the design of the NASA-ISRO SAR (NISAR) mission. In this
study, the capability of L-band simulated NISAR data for wetland mapping
in Yucatan Lake, Louisiana is investigated using two object-based
machine learning approaches: Support Vector Machine -(SVM) and Random
Forest (RF). L-band Unmanned Aerial Vehicle SAR (UAVSAR) data is
exploited as a proxy for NISAR data. Specifically, we evaluated the
synergistic use of different polarimetric features for efficient
delineation of wetland types, extracting 84 polarimetric features from
more than 10 polarimetric decompositions. High spatial resolution
National Agriculture Imagery Program imagery is applied for image
segmentation using the mean-shift algorithm. Overall accuracies of
74.33% and 81.93% obtained by SVM and RF, respectively, demonstrate
the great possibility of L-band prototype NISAR data for wetland mapping
and monitoring. In addition, variable importance analysis using the Gini
index for RF classifier suggests that H/A/ALPHA, Freeman-Durden, and
Aghababaee features have the highest contribution to the overall
accuracy.