Fusion of optical and SAR satellite data for environmental monitoring: assessment of damages and disturbances originated by forest fires

In this paper, we propose a processing chain jointly employing Sentinel-1 and Sentinel-2 data aimed at monitoring changes in the status of the vegetation cover by integrating the four visible and near infrared (VNIR) bands with the three rededge (RE) bands of Sentinel-2, approximately spanning the gap between Red and NIR bands (700 nm - 800 nm) with bandwidths of 15/20 nm and 20 m pixel spacing. The RE bands will be sharpened to 10 m and the resulting 7-bands, 10 m fusion product will be integrated with polarimetric features calculated from the Interferometric Wide (IW) Ground Range Detected (GRD) product of Sentinel-1, available at 10 m pixel spacing. Key point of the fusion of optical bands is the correction of atmospheric path radiance before fusion is accomplished through modulation of the interpolated band by a sharpening term achieved through the hyper-sharpening paradigm. Whenever surface reflectance data are available, haze estimation and correction can be skipped. Hyper-sharpening of Sentinel-2 multispectral (MS) bands and modulation-based integration of Sentinel-1 polarimetric synthetic aperture radar (SAR) features are applied on a multitemporal dataset acquired before and after a recent fire event.