Required format and location for downloaded S1 orbit files

Microwave Toolbox
#1

Dear forum users, developers,
I have a question regarding the correct format and location for S1 orbit files downloaded from ESA FTP (aux.sentinel1.eo.esa.int).

When processing S1 data (using SNAP5) I am getting the error messages (for both POEORB and RESORB):

WARNING: org.esa.s1tbx.sar.gpf.orbits.ApplyOrbitFileOp: No valid orbit file found for 06-OCT-2018 16:49:47.889909 │
Orbit files may be downloaded from https://qc.sentinel1.eo.esa.int/ │
and placed in /home/gisat/.snap/auxdata/Orbits/Sentinel-1/POEORB/S1A/2018/10

The hint in the error message indicates that the orbit files can be downloaded in advance and placed in the SNAP folder. On the FTP however the folder structure and orbit files format seem to be a bit different than the files downloaded by SNAP:

  • on the FTP there are no separate folders for S1A and S1B, in the SNAP home folder there are two folders created (S1A, S1B)
  • moreover on the FTP the orbit files are stored to months and days folders, which is not the case for SNAP home folder where all files are placed directly to month folder e.g. /.snap/auxdata/Orbits/Sentinel-1/RESORB/S1A/2018/10/
  • the orbit files on FTP are not compressed, but SNAP downloads them as ZIP archives

So my question is what shall be the approach for storing the orbit files so they can be correctly read by SNAP, which, I believe, can fasten the processing.

Thank you in advance.

Ondrej

Seninel-1 Apply Orbit File Error
Unable to Run Apply-Orbit-File from GraphProcessor
#2

@onalevka,

First of all, I would advice you to update SNAP. It seems you are still using v.5

For the orbits, in some cases I had a similar issue where I downloaded the orbits myself and put them in the appropriate folder to speed up processing time. That is how my folder structure looks like (and it works)

image
image.jpg785×170 59.8 KB

So you can see there is a folder por precise orbits, then one for S1A (or S1B), then year, month and finally the zip folder.

If you have used the Apply orbit file operator before, the folder structure should have been created already

Hope it helps,

M

#3

Hi MCG,
sorry for the delayed feedback. Thank you for your answer, will try your suggestions.

O.

#4

HI Snap Team, @marpet,
we are trying to use pre downloaded Precise Orbit Files. We have them locally and want to avoid downloading in a process chain. What would be the best solution to achieve this? A symlink to the files?
Best,
Peter

#5

Does this help? Applu-Orbit-File Step without internet

1 Like
#6

Yes thanks! It works!
We have symlinked the .\snap\auxdata\Orbits\Sentinel-1\POEORB\ folder to our local folder where the orbit files are. The structure is already the one needed by SNAP.

#7

very good!