Sentinel 1 Orbit File Problems

Microwave Toolbox
#1

Dear All,
I have been trying to create orbit files but due to the inability of SNAP 6 to read orbit file automatically or manually my work is stuck. Any help will be appreciated.

Roger

#2

Hello GeoAmit,

Do I understand you correctly in that you want to have SNAP use specific orbit files?

If so you can put them under: ~/.snap/auxdata/Orbits/Sentinel-1 if you are using Sentinel-1. In this directory there is POEORB/ and RESORB/ for Precise orbit files and restituted orbit files, respectively.

#3

Yes Sir, But the SNAP version 6 updated keeps refusing to accept orbit files stating" no appropriate orbit file found for the date ::__ and also does not accept any manually provided date downloaded from copernicus site that lists these. Now I must be either using files that do not have any associated orbit files or I am doing something amiss or the version is just got bugs. I don’t understand I tried using the sentinel1 tool (removed the SNAP for sometime) but to no avail as I had the same problem. It just does not automatically read orbit files as it should do. My files are of 2017 and have been used in a youtube video for showing backscatter interferogram etc. I repeated the steps only to find this bug. Later I tried using other file set also but I may have run into very bad luck that both files sets pairs SLC have no associated orbit files. Now that is strange. Kindly let me know what I can do.

Thanks and regards
Rogers

#4

The error message indicates that SNAP doesn’t read all metadata correctly. Have you already applied any pre-processing to the data?

#5

Could you please outline the steps you follow so that we can get a better idea of where the problem source might be?

#6

It has mysteriously started to work the moment I put my question on the forum. Thanks for all the help and advice. I guess it automatically started downloading srtm files during orbit file creation phase and everything seems to be working ever since. Thanks a lot.

#7

Ok I have another addition to the SNAPHU problem. If anyone could help it be great. i am able to do the following in my first system:

  1. Install snaphu for linux through src directory using make command. I am using VMware on windows 10.
  2. i am then able to copy my SNAP exported files to Snaphu ‘bin’ directory
  3. run snaphu with the line given in snaphu.conf file
  4. it runs slowly due to 4gb ram but it runs correctly every time

Here is the main probblem:
I try doing the same in a Xeon dual core Dell 490 with 32 GB RAM and from 3rd step (look above) onward it does not work. Meaning it keeps saying snaphu not installed use apt-get install snaphu …
Now I have replicated every step from my first pc where it works (but is not practical to run it there) into the second system which is a workstation . What am I missing since it just wont run on the workstation. I have gone over the process 20 times to make sure I am not missing anything. Everytime I have re-copied the sanphu-v1.4.2_linux files fresh so as to not use old files.

let me know if anyone can help.

Will be grateful

Roger

#8

Can you call snaphu from inside the bin folder? (Right click > Open shell here > type snaphu) If yes, you need to update your bashrc to make it available from any location.
http://www.troubleshooters.com/linux/prepostpath.htm
If no, snaphu was not compiled correctly or you are not permitted to execute it: https://www.pluralsight.com/blog/it-ops/linux-file-permissions

#9

did that, and solved it. Thank You . it seems everytime I start asking a question my problems start to resolve.

But this time I really need advice on different generic area. I am unwrapping SNAP exported image using VMWARE booted with linux with dedicated 24GB RAM / 32 GB of the system, using SNAPHU. I have xeon 51xx processor 3.0 GZ and 32GB RAM. How much time do you estimate this thing will take approximately - ball park range to unwrap? your video showed 3 minutes and 8 seconds…So would it be better if I did it with windows using Cygwin as your video suggests, but I am assuming you are using 256gb RAM and Xeon E5 1660 series at 3.2 GHZ or thereabouts. Please advice to the best course of action… My system has unwrapped 15 rows in about 40 minutes …I don’t know what that computes to in finishing terms duration…

Thanks and Regards
Rogers