Pre-processing of sentinel-1 grd

I cannot quite understand the difference between TERRAIN FLATTENING and TERRAIN CORRECTION. I know that the former is a radiometric correction while the latter is a geometric one. Are the two phases complementary?

The two operations are complementary, the help in the GUI should clarify the differences.

1 Like

Thank you very much for your reply, which GUI are you referring to?

SNAP Graphical User Interface.

Terrrain-flattening refers to the correction of topography-induced distortions to the image radiometry.
Terrain-correction refers to the correction of topography-induced distortions to the image geometry (transformation from radar geometry to map geometry).


thank you very much, sorry for my lack of preparation but I am at the beginning of my study

Thank you very much. While we’re at it, I’d also like to ask something else that I can’t understand: I am conducting a study on SAR time series analysis. I found an inconsistency in the acquisition date of some images before and after pre-processing. I made the download of this product: ‘S1A_IW_GRDH_1SDV_20220104T170623_20220104T170648_041314_04E951_3643’ so an image related to Jan 04, 2022. After the pre-processing step (in which I also applied the orbit file ) the product name is as follows: ‘S1A_IW_GRDH_1SDV_20220204T165804_20220204T165829_041766_04F863_4048’ so related to 04 Feb 2022. Is it normal for this to happen? What is the date I need to refer to?
Thank you

That should never happen. In many years of processing, I have never seen such a thing. It might be worth checking that you didn’t simply misattribute a second product you had on the same disk. Given that the orbit number is different (as expected) between two different dates, it appears that they really are two independent products, with the second not derivative in any way from the first.