GDAL `No such file or directory` when using unzipped SAFE file

[forrestfwilliams]

Currently, rtc_s1.py fails with a GDAL No such file or directory error if the input Sentinel-1 data is unzipped.

This can be recreated by processing the Los Angeles sample data hosted on zenodo, unzipping the provide SAFE file, then running rtc_s1.py with this configuration file.

This error occurs because calling s1reader's Sentinel1BurstSlc.slc_to_vrt_file() method writes a VRT representing the burst SLC data with a relative path to the parent geotiff that assumes the VRT is in the same directory as the SAFE file. However, in RTC this VRT is written to a temporary subdirectory with this structure:

input_dir
└── S1_SLC.SAFE
scratch_dir
└── temp_*
   └── temp_*
      └── BURST_ID
         └── slc_VV.vrt

Thus, GDAL is not able to locate the parent geotiff using the information in the VRT.

I can think of two ways to remedy this:

1. Modify Sentinel1BurstSlc.slc_to_vrt_file() so that it uses absolute file paths
2. Force RTC to write burst VRTs into the same directory as the input SAFE file

Personally, I prefer option 1 because it fixes the problem for other projects as well, and requires fewer code changes.
error.txt

[scottstanie]

My vote was also for (1) when I opened that issue here isce-framework/s1-reader#96

[forrestfwilliams]

Yep, I'd prefer option 1 as well. Thanks for pointing me towards the s1-reader issue!

[gshiroma]

Thank you, @forrestfwilliams , for reporting this issue. I agree with you and @scottstanie , that would be better to fix s1-reader. Thank you, @scottstanie , for opening the issue isce-framework/s1-reader#96 in that repository.