Pre-Processing Sentinel-1-Data

[geosilke]

Hi there,
I am new with Radar and Sentinel-1 data and I am not familiar with all the terms and definitions and physical basics. But motivated by a workshop for SAR-data I wanted to pre-process S1-data with the SNAP-tool, now. Unfortunately, I have no way to the goal so far.
My problem is, that I read and try different ways for pre-processing, but I don’t know, which one is the right and why and for which input dataset (sensing mode). I am a bit confused because about the many seeming options. For example the tutorial guide from ESA (Sentinel-1 Toolbox SAR Basics Tutorial, Luis Veci, Update 08/16) is different from some other online tutorials or the presentation I heared in the workshop (from SAR-EDU). Furthermore figures in the online help of SNAP looks not like the dialogs I used. There are additional parameters which are not explained. Some steps I learned in the workshop are running into errors and I don’t find details to the error message. I don’t want to post all my errors.

My overall question is:
Is there a general procedure or step-by-step instruction for pre-processing Sentinel-1-Data for the different sensing mode (IW-SLC, GRD - all modes which can be downloaded)? How do I know which guide is the right one for which condition?

I am very grateful for any hints!
thx, silke

[ABraun]

In general, there are many ways and different opinions on how to pre-process SAR images which makes it hard for beginners to get into it. For example there is much discussion on when is the best time for speckle filtering within the pre-processing.

For Sentinel-1 data there are some things which are widely agreed, please have a look at the following topics:

On the different products:

GTC (Geocoded terrain corrected) data

it means that its already ground-range corrected. Unlike SLC data the pixels' areas are already of same size. Astrium has made nice graphics for this case. They refer to TerraSAR-X but the principle is the same for most SAR satellites: Slant Range Complex (SLC/SSC/L.1.1) [image] Data is neither multi-looked nor projected Ground Range Detected (GRD/MGD/L1.5) [image] Data is multi-looked but not projected Geocoded Ellipsoid Corrected (GEC/L2.0) [image] Data is projected but topographic di…

On suitable orders:

Radiometric & Geometric Correction Workflow

for SLC data I would suggest Thermal noise removal Calibration to Beta0 TOPSAR Deburst Apply Orbit file (Speckle filtering) Radiometric terrain flattening Range Doppler Terrain Correction If you don't need the phase information you can also download it as a GRD product and only apply the following: Thermal noise removal Apply Orbit file Calibration to Beta0 (Speckle filtering) Radiometric terrain flattening Range Doppler Terrain Correction or (if you don't have much topography): The…

On multi-looking:

Multilooking necessary when geocoding?

Hello, I am fairly new to the SAR processing and I am trying to learn the basics through the ESA Sentinel Toolbox tutorials, which are a valuable resource. In the very first tutorial "SAR Basic Tutorial", I don't understand the role of the Multilooking process specially when compared with Geocoding. According to the tutorial, the "Multilooking can be an optional step, since it is not necessary when terrain correcting an image". But in the Terrain correction step of the tutorial, the input image …