Hi,
some L1C products are cut in two halves, with a little overlap, which provides you two products on the same date. In this case, the overlap is sufficient to allow you discarding the first one, but it is not always the same, for instance if the cut is in the middle of the image.
Initially, ESA was saying they would deliver “consolidated” L1C products that would merge both parts, but it was 4 years ago, and it is not done yet, so maybe they have given up.
where it seems to me that the former product was aborted and meant to be replaced by the latter - and as such contains no additional useful information,
and IMHO would better to be withdrawn from the archive.
As I said, for some reasons ESA has to cut its L1C products. They do it properly with an overlap, and provide each chunk of the same tile with the same acquisition date.
For instance, on the same date, here is the tile to the east of the one you displayed. It is cut too, and you don’t want to discard any of these as they don’t provide fully redundant information.
I know:
In fact four of the tiles I’m interested on that date: 32SMJ 32SNJ 32TMK 32TNK
all have similar ‘bad’ duplicates - and considering these tiles as a set I can’t see I am loosing any pixels by retaining only those published later rather than earlier.
But I’m ready to be convinced otherwise.
Update: Okay - I am convinced by your example.
Why! Oh why! do ESA have so many corner cases that need to be programmed around!
The UTM tile idea turns out to be such a pain when you have mosaic all these pixels from the the same swath back together again.
Well ESA and Copernicus already do a lot, but still leave us little things to complain about… The Frenchies like that
And the tiles have a few cons, but a lot of pros, they enable to process time series much more easily
Theia only delivers products with less than 90% of clouds, to save space, download time and computing resource: it reduces the amount of products by 1/3.
Olivier
For 2018.10.03 there are two almost identical products available for relative orbit 022 (at least over Sardinia)
They seem to differ in something called processing baseline - of which I know little but usually increments gradually over time -
• the former has a N0209 baseline S2B_MSIL2A_20181031T101139_N0209_R022_
and one split tile 32TNL
• while the latter has a N0211 baseline S2B_MSIL2A_20181031T101139_N0211_R022_
and no split tiles.
Q: Is it okay simply to favour the latter over the former?
(Ps: I’ve only ever encountered one case of such a ‘repeat product’ )
You can fins out more about the evolution of the processing baseline from Section 3.1 of the L2A Data Quality Report that we produce every month, and is made available from the S2 User Guide Document Library.
I guess that the S2B_MSIL2A_20181031T101139_N0211_R022_ product was an operational test that went well!
I notice that the N0210 baseline that followed that test lasted only a month - before incrementing properly to N0211 - was there some fix to be made?
Perhaps you might also explain a bit about the split tiles I’ve encountered (even during the N0211 baseline). Is there a technical reason why they haven’t been patched back to form a single product before presenting them to us? Or why I shouldn’t do so for a local archive?
The version of Processing Baseline (PROBAS) is incremented each time there is a significant update - evolution - of an instrument processing facility (IPF), or an update of a set of auxiliary data files (ADFs), or both.
Thus, 02.11 is a later evolution of the PROBAS, and therefore is an improvement on 02.09. Again, the specificity of these evolutions to the processing baseline are documented in the Data Quality Report (DQR).
The PROBAS is a GIPP - a Ground Image Processing Parameters file. To quote the Product Specification Document (PSD), these files are a set of XML files that are associated to each
processing component so as to define a particular set of parameters and their values.
The reprocessing of Tile 32TNL with 02.11 can also be identified in the increment of the date in the full filename:
The ‘split’ Tiles to which you refer are presumably split becuse they sit across the finish and start of two datastrips within a datatake, in this manner: