Offset Tracking result : Slice assembly vs. Non-Slice Assembly

s1tbx
#1

Dear SNAP User,

I’m needing to undertake some feature tracking of glaciers in East Antarctica using Sentinel-1 GRDH products.

I have been trying to work through the processing steps, following the tutorial from ESA.
I’m following these steps extremely closely. And, I have slice-assembled a master S1A scenes (after Apply Orbit file) and then attempted to dem-assisted coregister with slice-assembled a slave S1A scenes (after Apply Orbit file).

After applying the Slice Assembly tool, the Offset-Tracking result is different from the other result.

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Please could you tell me what is happening here, or suggest any additional processing steps that are required to fix this problem.

Toolbox Version: Sentinel-1 Toolbox 8.0.3

Operating System: Windows (10)

Relevant satellite products
S1A_IW_GRDH_1SSH_20170527T111015_20170527T111044_016766_01BDBB_32F3
S1A_IW_GRDH_1SSH_20170527T111044_20170527T111112_016766_01BDBB_0E7D
S1A_IW_GRDH_1SSH_20170702T111017_20170702T111046_017291_01CDD7_54CD
S1A_IW_GRDH_1SSH_20170702T111046_20170702T111114_017291_01CDD7_16A7
Direction: Ascending (All dataset)

Processing steps:
Slice-Assembled output:
Apply Orbit File (Sentinel Precise)
Slice Assembly
Dem-Assisted Coregistration (GETASSE30 - Auto Download)
Subset
Offset Tracking

Non-Slice-Assembled output:
Apply Orbit File (Sentinel Precise)
Dem-Assisted Coregistration (GETASSE30 - Auto Download)
Subset
Offset Tracking

#2

Slice Assembly probably applies some resampling on the input data which has an impact on the detected changes. Would it make sense to derive the offset first and then assemble the results?

1 Like
#4

Dear Mr. ABraun,

Thank you for your reply.
I have resolved the issue. I modified the previous process.

Modified Processing steps:
Apply Orbit File (Sentinel Precise)
Dem-Assisted Coregistration (GETASSE30 - Auto Download)
Subset
Offset Tracking
SAR-Mosaic

Thank you again in advice.

1 Like
#5

Thank you for sharing your solution