Applying Precise Orbit and aligning images

Hello All

First off, I’m new to the SNAP tool so hopefully I haven’t missed anything obvious that’s already documented or been answered.

My specific issue is with attempting to apply a precise orbit file to an SLC image. After waiting for some time, I eventually receive a SNAP error.


It appears to me that the orbit file is being retrieved and placed in .snap/auxdata/Orbits/Sentinel-1/POEORB/S1A/2018/12 as an EOF file. As a side note I am more than happy to manually download orbit files and apply them but this doesn’t appear to be possible with SNAP?

My particular situation may be complicated by having to run SNAP in a virtual machine (Debian 10). However, I have confirmed internet access and SNAP connectivity.

Can anyone shed any light on this or offer a workaround?

More generally, I am attempting to process two SLC images of the same region (not necessarily from the same aspect) to obtain complex ground plane images that I can export to HDF5 and overlay. Ideally I would have a georeferenced overlay in SNAP so that I could save two data files then load separately as aligned images in another tool. Second best would be to have arrays that just require shifts to align. What would be the best way to achieve this?

So far, I believe I need the following steps but am not 100% sure of the order. Any advice here would be appreciated.
Apply orbit; split swaths; calibrate; deburst; multilook; registration; slant to ground.

Long post, sorry!

Seemingly the problem is related to the RAM of your virtual machine, be advised there is no need to download the orbit manually if your VM. is connected to the internet!

Also be please copy and past this error or any other you could face it up in the future in the search function to find out in case of similar error is already discussed and solved.

Hi, Unless you need super precise localisation accuracy (< 3m) then you don’t need to use the precise orbit files (use the product header orbit data instead). Also why not try and use GRDH products first instead of SLC, espcially as you are multi-looking and converting to ground range.

Thanks for the reply. What indicates to you that the RAM is an issue? The VM has 32GB, I’d hope that would be enough!

I realise that I shouldn’t need to manually download the orbit files, I was trying that in the hope of getting something working.

I can already work with GRDH products outside of SNAP. The point of using SNAP is to apply the correct processing to SLC to end up with a ground plane image from that data product.


This is general error message, one of many and essential things is, RAM capacity,


But in this case the RAM is really enough, even if it were 16 GB, it’s also enough, but with longer time of each process.

Also in SNAP, you could work with GRDH to shorten the time, as @peter.meadows has mentioned as well.

To apply orbit, please check this box,