Error when performing SliceAssembly with S1 images acquired in May 2016

Hello everybody,
I’m using SNAP 8.0.
The utility “Check for updates” has been performed also.
Now, I’m trying to assembly the following two slices:
The two slices are available at the following links:‘a874fb02-f6ef-4f70-b7b6-f394ae6503b5’)/$value‘babcf95e-1ea8-41e8-9eb8-49c7f1fed949’)/$value

When I try to assembly them, I get the following error:

Please, anybody has any suggestion to attempt to solve this issue?
Thanks in advance

does this error occur for other image pairs as well or only this one?

If so, have you checked if the data was correctly downloaded? Try to open a sub-swath of each of them and see if it can be displayed.

Dear Andreas,
thanks a lot for your reply.

Yes, I have checked successfully the integrity of the two zip-files, by comparing the md5sum. No problem at all when trying to open any sub-swath of each of them!

Furhermore, the error occurs by processing the two products stored in the SCIHUB, as well as the corresponding products stored in the CREODIAS (unzipped, in the last case).

I’m processing a stack of image pairs, acquired on relative orbit 015 since April 2015 to date (so, more than 250 acquisition dates). The reported error does not occur sistematically for all the acquisitions but only for a number of around 30 pairs acquired between April 2015 and May 2016.
So it is not an “isolated pair”, but this error impacts on a significant number of SLC pairs. No errors instead when assembling slice pairs acquired later than May 2016.

Do you have any other suggestion?

PS: I’m working on servers with more than 32GB of RAM, and the error occurs on both Linux and Windows platforms, and by using the snap graphic interface, as well as the gpt batch script

thank you for the detailled feedback.
Doesn’t sound like a processing error then, but rather caused by the datafiles themselves. Probably only one of the two is faulty… I’m not sure if there are other S1 products around which were processed by a different facility. Could you please check if the same happens for these scenes when downloaded from ASF Data Search?

Unfortunately, the problem arises also with products downloaded from the “ASF Data Search” Facility

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@lveci if this is a bug it should be fixed in the first module update.

I have downloaded two more products belonging to the same track, so now I have:

Then, I tried to assembly subsequent pairs, with the following results:
[2]-[3]: SLICE_ASSEMBLY COMPLETED WITH ERROR (exactly what I reported before)

I’m wondering if the problem concerns the software (SNAP) or the S1 products.
Unfortunately, ther is not a verbose logfile that I can copy and paste here.
That’s all, at the moment …

Any news or suggestions?

The IPF was updated around that time to fix an issue which affected slice boundaries. If the reports or earlier, you might be running into that issue, solved in 2.71. If the image was reprocessed with a later version, this should not apply.
Version 2.71 was deployed for products after 2016-05-11 12:00:00. The timing is suspicious…

If this is indeed your problem, there’s not much you can do. The L0 data would need to be reprocessed.

Dear Eric,
thanks a lot for your reply.
I have analyzed the manifest files of all the SLC products: the IPF version of all of them is higher than 2.70, ranging from 2.71 to 3.31.
So, it seems that the problem you have mentioned does not apply in my case.

However, I have to report that the error occurs systematically for all and only the SLC slice pairs that have been focused with a different IPF version. More specifically, this happens with the IPF versions 3.10 and 2.72, respectively for the first and second slice!!

Here below I list all the slices where the error occurs, together with the corresponding IPF release:

S1A_IW_SLC__1SDV_20150404T171421_20150404T171448_005337_006C3A_FF59 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150404T171446_20150404T171513_005337_006C3A_BACC [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150416T171422_20150416T171449_005512_00709D_A62B [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150416T171447_20150416T171514_005512_00709D_755D [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150510T171423_20150510T171450_005862_0078B5_3715 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150510T171448_20150510T171511_005862_0078B5_3EC8 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150522T171424_20150522T171451_006037_007CBA_CB75 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150522T171449_20150522T171516_006037_007CBA_3050 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150603T171425_20150603T171452_006212_0081AF_4488 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150603T171450_20150603T171512_006212_0081AF_D8B9 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150615T171426_20150615T171453_006387_0086C9_F7D9 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150615T171450_20150615T171507_006387_0086C9_5DE0 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150627T171426_20150627T171453_006562_008BB6_FBF6 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150627T171451_20150627T171514_006562_008BB6_4E78 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150709T171426_20150709T171453_006737_009069_84B4 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150709T171451_20150709T171507_006737_009069_676B [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150721T171427_20150721T171454_006912_00957B_9A46 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150721T171452_20150721T171509_006912_00957B_2FFB [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150814T171428_20150814T171455_007262_009F26_B84C [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150814T171453_20150814T171510_007262_009F26_1FC0 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150826T171429_20150826T171456_007437_00A3E8_75B8 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150826T171454_20150826T171510_007437_00A3E8_6B98 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150907T171429_20150907T171456_007612_00A8B1_7AD2 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150907T171454_20150907T171511_007612_00A8B1_66B5 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20150919T171429_20150919T171456_007787_00AD57_7BB0 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20150919T171454_20150919T171511_007787_00AD57_2475 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151001T171430_20151001T171457_007962_00B212_8908 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151001T171455_20151001T171511_007962_00B212_7530 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151013T171429_20151013T171456_008137_00B6BC_D93A [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151013T171454_20151013T171512_008137_00B6BC_3212 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151025T171430_20151025T171457_008312_00BB87_5CBC [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151025T171455_20151025T171522_008312_00BB87_BAAF [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151106T171430_20151106T171457_008487_00C017_9424 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151106T171454_20151106T171521_008487_00C017_7C8B [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151118T171424_20151118T171451_008662_00C501_F517 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151118T171449_20151118T171516_008662_00C501_C721 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151130T171429_20151130T171456_008837_00C9E6_5796 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151130T171454_20151130T171521_008837_00C9E6_A2EC [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151212T171423_20151212T171450_009012_00CEC5_400B [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151212T171448_20151212T171515_009012_00CEC5_6FB1 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20151224T171428_20151224T171455_009187_00D3BB_194C [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20151224T171453_20151224T171520_009187_00D3BB_0E6F [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160117T171427_20160117T171454_009537_00DDB4_859D [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160117T171452_20160117T171519_009537_00DDB4_82DF [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160129T171421_20160129T171448_009712_00E2DB_6FCF [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160129T171446_20160129T171513_009712_00E2DB_0785 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160210T171427_20160210T171454_009887_00E7E2_90E1 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160210T171451_20160210T171518_009887_00E7E2_FEDF [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160305T171427_20160305T171454_010237_00F1FA_DEA6 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160305T171452_20160305T171519_010237_00F1FA_FF21 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160317T171422_20160317T171449_010412_00F6EF_FD1D [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160317T171446_20160317T171513_010412_00F6EF_76F7 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160329T171428_20160329T171454_010587_00FBF9_2478 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160329T171452_20160329T171519_010587_00FBF9_CEF2 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160410T171422_20160410T171449_010762_010122_A11F [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160410T171447_20160410T171514_010762_010122_849F [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160422T171423_20160422T171450_010937_010677_168F [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160422T171448_20160422T171515_010937_010677_CCA8 [IPF ver.:2.72]

S1A_IW_SLC__1SDV_20160504T171423_20160504T171450_011112_010BED_04A2 [IPF ver.:3.10]
S1A_IW_SLC__1SDV_20160504T171448_20160504T171515_011112_010BED_965C [IPF ver.:2.72]

I notice also that the error does not occur in all the cases where it happens the contrary, i.e. the first slice is focused with IPF ver. 2.72 and the second one with version 3.10.
This is the case of the following SLC pairs:

S1A_IW_SLC__1SDV_20150428T171413_20150428T171440_005687_0074BD_3B88 [IPF ver.:2.72]
S1A_IW_SLC__1SDV_20150428T171437_20150428T171510_005687_0074BD_87A1 [IPF ver.:3.10]

S1A_IW_SLC__1SDV_20150802T171417_20150802T171444_007087_009A61_5395 [IPF ver.:2.72]
S1A_IW_SLC__1SDV_20150802T171442_20150802T171509_007087_009A61_4D3D [IPF ver.:3.10]

Finally, no errors are reported when the IPF version is the same for the two slices.

I hope this can help to find a fix …
I wonder again if it is a bug of the SNAP software rather than an inconsistency that just requires L0 data to be reprocessed.
Any suggestion?
Thanks again

PS: obviously, the results do not change if I try to invert the order of the images to provide in input to the SliceAssembly operator

Dear all, any good news :slightly_smiling_face: ?

I’m not sure if this is a bug or an issue of IPF versions incompatibility when trying the stich together a single data take. @nuno.miranda is this is expected behaviour in your opinion?

Dear Marcus and all,

It is clear that some slices of the same data-take has been reprocessed with a newer IPF version. In general, we pass the message to our PDGS colleagues to reprocess all the data-take (several slices) to avoid this situation.

Now, last week, I looked at two products reporting as giving problem. From a timing point of view it all looks consistent i.e. the burstList and swathTiming annotation doesn’t show any obvious discontinuities and similarly applies to the time sampling.

I can’t figure out any good reason for which this data can’t be stitched. I would recommend the SNAP team to perform some analysis on that. Could you please look into that direction and let me know after?

Kind Reg.

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