SI TOPS coregistration - Same sub-swath is expected

Dear developers,

I am trying to co-register two Sentinel1 images using the S1 TOPS Co-registration tool. Each SLC image is consisted of three sub-swaths. In order to apply the co-registration, we need to find our area of interest in both images. In the first SLC image, my area of interest falls into sub-swath 2 and in second SLC image, the same area falls into sub-swath 3. When trying to co-register the two images i get the error ‘Same sub-swath is expected’.

What happens in my case where the area of interest fall into different sub-swaths between the two acquisitions?
What if I first execute the ‘TOPS split’ command for both images and then co-register them using the ‘coregistration’ method instead of ‘S1 TOPS Coregistration’.

Is this procedure going to affect the results or it’s exactly the same?


Both images should have the same path and same frame, in this case your study area will be located in the same SUBSWATH in both images as well as in the same bursts,

Hi falahfakhri,
The first image acquired in March of 2016 and the second one in April of 2016 (1 month difference).
Both images acquired in ascending orbit.
Orbit cycle of image in March: 75, orbit cycle of image in April: 77

The problem is that my area does not fall into the same sub-swath of the two image acquisition.
How is this possible?


My question is do they have the same PATH AND FRAME, would you please to check out this issue

Can you please tell me where to find this information?
I have went through the metadata file and could not find ‘path’ and ‘frame’


in the website that you have downloaded the images from

The path is given as the RELATIVE ORBIT entry

If you have an area which lies on two sub-swaths, the TOPS coregistration is not suitable, as you say. Possible solutions:

  • running TOPS coregistration for each sub-swath and mosaic the results
  • deburst (and clip) the products first and coregister using the common tool.

Neither of them is suitable for interferometry as they leave breaks in the interferogram - at least in my experience.

Ohhhh, right, it is given as an orbital path. Now I can find it. thanks
So, in order to achieve a good quality of interferogram, the orbit track of the satellites must be the same, right?
Otherwise, we get poor results?


Exactly. If you would use data with different paths you have different looking angles and too large baselines (distance between both satellites at the time of acquisition). Both are bad for interferometry :slight_smile:

hmmm I got it.

thank you :slight_smile:

how can I find the frame id?
RELATIVE ORBIT is the path, what is the frame?
we need both of them, am I right?