Help with Sentinel-1 SNAP Command Line "Write" function

snap
1

I am processing Sentinel-1 SLC images to get PolSARPro output format using the gpt command line.

This is the workflow I am using:

Read > TOPSAR-Split > Apply-Orbit-File > Calibration > TOPSAR-Deburst > Polarimetric-Speckle-Filter > Terrain-Correction > Write

I have tested the output after every step and compared it to the output when using the SNAP GUI. Everything works well until the “Write” step.

When I export the output of the ‘Terrain-Correction’ using the GUI, it works fine. I also tested using a read > write graph, and it also works fine. However, when I use the command prompt to write the output file to PolSARPro format, the values are all 0, although the file size is similar to the output from the GUI.

Here is what I did:

################## Terrain-Correction
Stage7: run “cd d:\snap_cmd\terrain_correction_iw1_output”

Stage7b: run “gpt Terrain-Correction -Ssource=D:\snap_cmd\pol_speckle_filter_iw1_output\target.dim -PpixelSpacingInDegree=8.983153E-5 -PpixelSpacingInMeter=10”

################## Write
Stage8: run “cd d:\snap_cmd\write_iw1_output”

Stage8: run “gpt Write -Ssource=D:\snap_cmd\terrain_correction_iw1_output\target.dim -Pfile=D:\snap_cmd\write_iw1_output\S1B_IW_SLC__1SDV_20210613T004848_20210613T004915_027331_0343A9_3F05_proc_iw1 -PformatName=‘PolSARPro’”

This command reads the product from D:\snap_cmd\terrain_correction_iw1_output\target.dim and writes it to D:\Hansanee_PhD\s1_cmd_process\snap_output\target.hdr in PolSARPro format.

Despite the correct file size, the values are all 0 when using the command line. How can I resolve this issue?

2

Jira ticket SNAP-3720 created.

3

I don’t think you should run “Write” as an operator from the gpt command line. I would suggest you run a graph from the command line. If you have already got the processing result and now just want to convert it to PolSARPro format, you can create a simple graph with just Read and Write and run it from command line.