I am a beginner of SAR images. I processed the sentinel-1 images for flood mapping using SNAP based on step-by=step user manual. I got a flood map, but seems accuracy is too low when comparing with reference data. I want to adapt other methods to improve accuracy. It seems Clement, M. (2017) Multi-temporal synthetic aperture radar flood mapping using change detection, mentioned a possible solution. It used HAND for terrain filter, can it adaptable in SNAP? Or I should process the images by other software? Any intermediate graded user manual for SNAP or other software?