Speaker
Dr
David Small
(University of Zurich)
Description
Modern SAR sensors are increasingly offering wide swaths, enabling shorter revisit intervals than were hitherto possible. The new open data policy of Sentinel-1 enables the development of higher level products, built on a foundation of level 1 SAR imagery that meets a high standard of geometric and radiometric calibration. We systematically process slant or ground range Sentinel-1 data to terrain-flattened gamma nought backscatter. After terrain-geocoding, multiple observations are then integrated into a single composite in map geometry.
Although composite products are ubiquitous in the optical remote sensing community (e.g. MODIS), no composite SAR backscatter products have yet seen similar widespread use. In the same way that optical composites are useful to avoid single-scene obstructions such as cloud cover, composite SAR products can help to avoid terrain-induced local resolution variations, providing full coverage backscatter information that can help expedite multitemporal analysis across wide regions. The composite products we propose exhibit improved spatial resolution (in comparison to any single acquisition-based product), as well as lower noise and backscatter stability. In addition, backscatter variability measures can be easily added as auxiliary channels.
We demonstrate a new type of SAR backscatter product based on robust radiometrically terrain corrected backscatter images. We show results from the first year of calibrated Sentinel-1 data, covering the whole of the European Alps. The composite backscatter product type can be generated first at medium resolution (e.g. 100m), with a ramp up to higher resolutions possible as higher resolution DHMs become available together with improved network bandwidth and computing resources.
The products could see application in all of the listed the fields, including
- snow cover mapping
- hydrology
- agriculture
- general land-use and classification.
Primary author
Dr
David Small
(University of Zurich)
Co-authors
Dr
Adrian Schubert
(University of Zurich)
Mr
Christoph Rohner
(University of Zurich)
