Creating A Digital Elevation Model using Sentinel-1 Data

Guide to Creating a Digital Elevation Model Using Sentinel-1 Data in the Sentinel Application Platform (SNAP)

Create a DEM using Sentinel-1 Data

This tutorial will guide you through creating a Digital Elevation Model (DEM) from two Sentinel-1 SLC scenes by first creating an interferogram, and completing the needed phase unwrapping steps, to finally create the DEM.

Background

Pair Selection for DEMs

Sentinel images to create the DEM can be downloaded using the Copernicus Browser (LINK). The ideal pair for the creation of our DEM would have a large perpendicular baseline and a small temporal baseline.

More Details for Pair Selection

Overlap in the imagery is essential. The Pair needs to share the same path number and cover the same area. Images taken with different flight directions (ascending vs descending) cannot be used as pairs for interferometry.

Coherence is crucial. You should select images with the shortest possible temporal baseline. This will minimize both coherence loss and potential surface motion. A larger time span between images will lead to higher decorrelation.

Baseline is important. The perpendicular baseline does significantly affects the sensitivity of the interferogram to height variations. While a larger baseline improves sensitivity, it also reduces coherence. If the perpendicular baseline exceeds approximately 3/4 of the critical baseline (about 5 km for Sentinel-1A), the images will likely become decorrelated.

Steps

Opening Data in Sentinel-1 Toolbox

• Open the Products
• View the Products
• Visualize a Band

Coregister the Data

• Coregister the Images

Interferogram Formation and Coherence Estimation

• Form the Interferogram

Visualize Interferometric Phase

• TOPS Deburst

Multi-looking and Phase Filtering

• Phase Filtering

Unwrap an Interferogram with SNAPHU

• Export to SNAPHU
• Install a Linux VM
• Unwrap an Interferogram with SNAPHU
• Move Files to PC/Mac

Open the Files in Sentinel-1 Toolbox

• Snaphu Import

Geocode the DEM

• Terrain Correction

Details

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