Flood Mapping with Sentinel-1 SAR Using ENVI SARscape Analytics toolbox | Automated Workflow скачать в хорошем качестве

Flood Mapping with Sentinel-1 SAR Using ENVI SARscape Analytics toolbox | Automated Workflow

This tutorial demonstrates how to map flood extent automatically using Sentinel-1 radar imagery and the ENVI SARscape analytics toolbox. The video walks through loading one pre-flood and one post-flood Sentinel-1 scene into ENVI, running the SARscape Flood Mapping workflow, and generating a binary flood mask. (A third post-flood image is shown only for validation.) Note that the narration sometimes (incorrectly) says “Sentinel-2,” but the data used are Sentinel-1 SAR images (C-band radar) . Sentinel-1’s all-weather, day/night capability makes it ideal for flood mapping, unlike optical Sentinel-2 . The video highlights backscatter change detection and automated classification to identify standing water. Clarification: Any reference to Sentinel-2 is a mistake throughout the video– the workflow uses Sentinel-1 SAR data (VV/VH polarization). The SARscape flood mapping tool compares radar backscatter before and after flooding . In practice, we use one or more pre-event Sentinel-1 scenes plus at least one post-event scene (along with a DEM) to classify water . A second post-flood image (from the same Sentinel-1 mission) is only used to check accuracy. Sentinel-1 SAR can “see” through clouds and at night, enabling flood detection even in bad weather Tools & Techniques The ENVI SARscape Analytics Toolbox provides an automated Flood Mapping workflow for SAR data. In this workflow: pre- and post-event Sentinel-1 SAR images (and a DEM) are processed to produce a flood mask . Key steps include speckle filtering and radiometric/geometric calibration of the SAR images . Then a backscatter change detection is performed (often by taking the pixel-wise ratio or difference of post-/pre-flood images). High-change pixels indicate water; applying a threshold yields a binary flood/no-flood classification The video shows how this workflow runs in ENVI SARscape with minimal manual tuning. Input Data: Sentinel-1 SAR scenes (C-band, typically VV or VH) acquired before and after the flood event. The SARscape Flood Mapping tool can use one or more pre-flood scenes and one post-flood scene Preprocessing: The SAR images are filtered and calibrated (speckle reduction, geometric/radiometric calibration using a DEM) to normalize backscatter values Change Detection: The post-event image is compared to the pre-event image (e.g. ratio or difference). Pixels with a large drop in backscatter are classified as water Automated Output: SARscape outputs a classification raster highlighting flooded areas as shown by the blue flood polygons in the example above. This flood map can be overlaid on satellite imagery or exported to GIS. Applications Disaster Response: Rapid flood extent mapping is critical for emergency planning and relief. SAR-based flood maps can be generated even under clouds or at night nv5geospatialsoftware.com . Waterbody Monitoring: The workflow also applies to tracking reservoirs, wetlands, and river inundation by classifying standing water before/after events envi.com.br . Risk Assessment: Quantifying flood-inundated areas helps planners understand flood frequency and high-risk zones nv5geospatialsoftware.com . Timely SAR flood products support resilient infrastructure design and water resource management. Keywords Sentinel-1 flood mapping ENVI SARscape Analytics SAR flood detection disaster mapping backscatter change detection remote sensing tutorial waterbody monitoring Call to Action: If this tutorial was helpful, like and subscribe for more remote sensing and disaster mapping videos. Check out our channel for related ENVI/SARscape tutorials and resources on flood mapping and SAR analysis!