Sentinel-2 L2A products crops unpredictably

bwh1te · June 3, 2020, 10:41am

I’m using sentinelhub-py (3.0.2) library to get access to L2A products (NDVI, trucolor). I’m doing WCS requests with providing geometry to request parameters. Sometimes it works well, but sometimes SentinelHub responds with only part of expected polygon.

First one fits the expected geometry:

Second one is just a part of it:

Request: https://services.sentinel-hub.com/ogc/wcs/<SENTINEL_HUB_ID>?SERVICE=wcs&WARNINGS=False&MAXCC=100.0&Transparent=True&ShowLogo=False&Geometry=POLYGON+((55.836197+49.183942,+55.768846+49.075897,+55.722627+49.152511,+55.807505+49.294738,+55.836197+49.183942))&BBOX=55.72262693608201,49.07589738642747,55.83619728590895,49.29473760449088&FORMAT=image/png&CRS=EPSG:4326&TIME=2020-05-27T07:14:24/2020-05-27T09:14:24&RESX=10m&RESY=10m&COVERAGE=TRUECOLOR_S2_L2A&REQUEST=GetCoverage&VERSION=1.1.2

I thought I’ve found the solution: I just replaced TIME=2020-05-27T07:14:24/2020-05-27T09:14:24 with TIME=2020-05-27T00:00:00/2020-05-27T23:59:59 (whole day) and this way I got the expected whole picture for 2020-05-27! But I’ve also tried it with another dates and unfortunately it doesn’t always work… For example 2018-06-12:

I’ve tried to set:
TIME=2018-06-12T08:14:08/2018-06-12T08:14:08
TIME=2018-06-12T07:14:08/2018-06-12T09:14:08
TIME=2018-06-12T00:00:00/2018-06-12T23:59:59
(I’m using 'time_difference': timedelta(hours=1) parameter by default)
No changes.

What did I do wrong?

gmilcinski · June 3, 2020, 11:29am

Might it be that this polygon is on the border of the orbit and there is simply no data there?
Can you check how the scenes look in EO Browser? This will give you mich better insight into what is happening.

Generally though, if you set it to full day, you will get all the data available within the orbit.

bwh1te · June 3, 2020, 11:30am

Some additions.

According to available scene history, there are scenes like this:
(datetime.datetime(2018, 6, 11, 7, 46, 45)
(datetime.datetime(2018, 6, 12, 8, 6, 5)
(datetime.datetime(2018, 6, 12, 8, 14, 8)
(datetime.datetime(2018, 6, 14, 7, 56, 7)

Polygon is not on the border of tile. Bigger one is tile, inner is my AOI.

gmilcinski · June 3, 2020, 12:11pm

Not sure, what is on your image - it is not the same as above as there are no clouds.

I now went to EO Browser (this location)

and it looks to me it is on the border of the orbit as I suggested: