You should be a bit objective oriented. Actually what is your actual application? Sentinal 1 free data is available in different levels! Which data did you downloaded?

I found there are three types of data on the Sentinel Scientific Data Hub: **SLC_1SDV_**/ **RAW__0SDV***/**GRDH_1SDV***.

I download S1A_IW_GRDH_1SDV_** data. 

First maybe I need make a Lee  fitter to the data? Then the geometrically corrected.

I just want to use the data to discriminate the water and vegetation.

If I need another process?

Thanks in advance.

Perhaps is better to perform the geometric correction and the start applying some speckle filtering.

A basic way to do what you need can be to first give a look to the histogram of the filtered image in order to try to find the two characteristic peaks of land and water areas and the intensity value which better separate.

Then to apply such intensity value by means of Utilities -> Create Band from Math Expression... and see the result.

A more flexible way can be to apply this processing into a Graph (Graphs -> Graph Builder) which also would allow you to apply the same method to more images (but you will need always to determine manually the intensity threshold).

I'm sure you figured it out by now, but the Sentinel-1a Toolbox tutorials are very instructive. Look at all of them (even if you think you won't be looking at that specific type of data) because some of the key information important to others is buried quite well. See: 

https://earth.esa.int/web/sentinel/toolboxes/sentinel-1/tutorials

For the processing of Sentinel-1 L0 product you can use FreeSAR (http://www.freesar.com/). This web-based framework allows you to generate L1 products and perform interferometric analyses (data coregistration, interferograms generation, Persistent Scatterers analysis). For any question or issue you can send an e-mail to [email protected].

https://scientiaplusconscientia.wordpress.com/2015/08/06/working-with-sentinel-1-data-pre-processing-georeferencing-and-exporting-with-snap/

Have a look at this paper : Conference Paper LAND COVER MAPPING USING SENTINEL-1 SAR DATA

Conference Paper LAND COVER MAPPING USING SENTINEL-1 SAR DATA

http://step.esa.int/main/doc/tutorials/

if you use GRD, follow these steps:

1- apply orbit file

2- radiometric calibration

3- speckle filtering

4- Rang-Doppler terrain correction

Dear Xingxing Han

ESA's tutorials may also help.

http://step.esa.int/main/doc/tutorials/

Regards

https://earth.esa.int/web/sentinel/toolboxes/sentinel-1/tutorials

You can use SNAP software package developed by ESA for processing the Sentinel-1 data.

if you use GRD, follow these steps:

1- apply orbit file

2- radiometric calibration

3- speckle filtering

4- Rang-Doppler terrain correction

Hi, try this youtube link.

1- https://www.youtube.com/watch?v=kaZLp8JGlXc&t=1s

2- https://youtu.be/7w_-deMSRTs

good luck.

https://www.youtube.com/watch?v=kaZLp8JGlXc&t=1s

https://youtu.be/7w_-deMSRTs

Hello Xingxing Han, specific steps for the preprocessing of any SAR data depends upon the area of application, the sensor, and the type of data product being used(for example, in Sentinal-1, we have different products like SLC, GRD, and OCN).

Though basic steps involved in the pre-processing of Sentinal-1 SAR data are :

Applying Orbit file > Thermal noise removal > Calibration > Terrain flattening > Speckle filtering > Terrain Correction

Note: Additional steps may be required, or few steps can be excluded from the above flow diagram depending upon the area of the application and the data product.

A detailed study on the flow of preprocessing steps along with its automation process using ESA's SNAP S-1 toolbox is presented in this article: Article Sentinel-1 SAR Data Preparation for Extraction of Flood Foot...

I agree with Kuntla Sai Kiran

http://step.esa.int/main/doc/tutorials/

Please see this document : https://servirglobal.net/Portals/0/Documents/Articles/2019_SAR_Handbook/SAR_DataProcessing_1page_new.pdf

Hi Xingxing Han

Here you can find some ideas.

https://eo4society.esa.int/resources/advanced-training-course-on-land-remote-sensing-with-the-focus-on-agriculture/

Just grep for S1