ifm_sentinal.py always picks the older file as reference, and newer file as secondary.

[cirrusasf]

Describe the bug
A clear and concise description of what the bug is.
I also found that even if we choose the file with later date time as the reference in the pair of files, the ifm_sentinal.py always picks the file with earlier date time as reference one, I suppose ifm-sentinal.py should produce the ifm with reference file is later than the secondary file.

For example,
Case1 (forward):
ref=S1A_IW_SLC__1SSV_20160112T205113_20160112T205140_009466_00DBA8_C430
sec=S1A_IW_SLC__1SSV_20160628T205108_20160628T205136_011916_01259C_EE11
output:S1AA_20160112T205113_20160628T205108_VVP168_INT80_G_ueF_5027.zip
Slant range near: 800208.3153
Slant range center: 879343.5365
Slant range far: 958478.7576
Case2 (backward):
Ref=S1A_IW_SLC__1SSV_20160628T205108_20160628T205136_011916_01259C_EE11
sec=S1A_IW_SLC__1SSV_20160112T205113_20160112T205140_009466_00DBA8_C430
Output: S1AA_20160112T205113_20160628T205108_VVP168_INT80_G_ueF_7E78.zip
Slant range near: 800208.3153
Slant range center: 879343.5365
Slant range far: 958478.7576

Actually, the metadata.txt in two cases are the same. Furthermore, I found in both cases, no matter if you reverse the ref and sec, ifm_snetinal.py always produces the same result which always uses a file with earlier time as a ref file.

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Expected behavior
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Additional context
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[jhkennedy]

I'm not sure this is a bug -- we intentionally order products this way as your stack needs to be consistently processed in time (you can go earlier first always, or latest first always, but not a mix).

Do you want an option to select which direction? Or do you want us to invert the ordering?

[cirrusasf]

Hi Joe, As I showed the example in the issue. No matter if I switch the ref with sec, the ifm_sentinal.py always picks up the one with an earlier date time as the ref. That means we can not choose the later date time file as the ref in the ifm_sentinal.py. Jiang

…

On Fri, Jun 11, 2021 at 11:41 AM Joseph H Kennedy ***@***.***> wrote: I'm not sure this is a bug -- we intentionally <https://github.com/ASFHyP3/hyp3-gamma/blob/465c96253419a4470492aa2b8cfc31ca094cbe2d/hyp3_gamma/__main__.py#L112> order products this way as your stack needs consistently processed in time (you can go earlier first always, or latest first always, but not a mix). Do you want an option to select which direction? Or do you want us to invert the ordering? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#269 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AO3CPWAMLCHVVJR2XO2AK53TSJRGHANCNFSM46RLLJMQ> .

[jhkennedy]

That means we can not choose the later date time file as the
ref in the ifm_sentinal.py.

Yes. I'm saying that's intentional. Do you need oldest first, and if so why? Do you want ordering as an option, or the enforced ordering inverted?

[cirrusasf]

Hi Joe, I would like to have ordering as an option. I think this gives users a flexibility to do time series analysis based on the file with the newest date time as the reference. Jiang

…

On Fri, Jun 11, 2021 at 12:31 PM Joseph H Kennedy ***@***.***> wrote: That means we can not choose the later date time file as the ref in the ifm_sentinal.py. Yes. I'm saying that's *intentional*. Do you need oldest first, and if so why? Do you want ordering as an option, or the enforced ordering inverted? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#269 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AO3CPWCVT35XA2MNHWJMIFTTSJXBPANCNFSM46RLLJMQ> .