Sentinel 2 id generator

Disclaimer: This not yet ready-to-use. Seriously ... come back later.

This README was generated by a jupyter notebook and automatically exported into Markdown. You might want to open the README.ipynb file to see the original outputs. Do not edit the Markdown file directly as any changes will be overwritten.

1. Problem

There is no unique universal identifier (uuid) for Sentinel data, which is valid across all data hubs and is unique for the distinct images. Even within a data hub (e.g. the Copernicus Open Data Hub) the same image might have different uuids.

To have a clean database in the EO-Compass and the data cubes, we need an id generator which generates reliably identical ids for identical images and distinct ids for distinct images. In this way, a UNIQUE constraint in the metadata table is able to prevent duplicate entries. The semantics of what identical images are is not the job of the database.

2. Sentinel-2 metadata structure (relevant elements)

For the first version the granule id (according to the UTM grid) and the acquistion time will be used. The formatting is as follows according to the naming convention (https://sentinel.esa.int/web/sentinel/user-guides/sentinel-2-msi/naming-convention):

#
# Tile/Granule id / Footprint / UTM grid id
#
# General pattern: Txxxxx
#
# Example:
#
granule_id = 'T33UVP'

#
# Acquisition time
#
# General pattern: YYYYMMDDHHMMSS
#
# Example:
#
acquisition_time = '20170105T013442'

#
# Relative orbit
#
# General pattern: integer
#
# Example:
#
rel_orbit = 122

3. Initial considerations

There will be a (simplified) version 1 of the Sentinel-2 id generator, which is scene-based. I.e., it takes a scene name according to the UTM grid and the acquisition time. The version 2 of the Sentinel-2 id generator will work on arbitrary geographic regions.

3.1 Identical images

When are two images identical?

When they have:

• the same acquisition time
• the same footprint
• ... tbd

3.2 Image sub-sets and partially identical images

It should be reflected that an image is a sub-set or partially identical with another image.

3.3 Image footprints

It should be reflected in the id that two images have the same footprint, but were acquired at different times.

3.4 Acquisition time

It is reasonable to expect that there is a time tolerance of a few miniutes required. For example the temporal granularity might be 5 minutes (neglecting day/night changes for simplicity).

3.5 Image versions

Images might be re-processed by ESA using a different software version. The version should be reflected in the id.

4. Example / general pattern

Version 1:

{granule-id}-{rel_orbit}-{acquisitionyear}-{acquisitiondayofyear}-{acquisitionhour}-{acquisitiontime (minutes / 5)}

t33uvp-122-2017-005-01-6

Version 2 might be something like this:

{instrument}-{platform}-{processinglevel}-{...?}

MSI-A-1C-...?

5. Usage

Use the package as follows

#
# Import the package
#
from s2_idgen import s2_idgen

#
# Generate a new id
#
id = s2_idgen.Generator(
    granule_id = 'T33UVP',
    acquisition_time = '20170105T013442',
    rel_orbit = 122)

#
# Access the id
#
id.getID()

't33uvp-122-2017-005-01-6'

6. Development

Clone the repository:

git clone https://github.com/ZGIS/sentinel-2-id-generator.git

Change working directory

cd sentinel-2-id-generator

Create and activate the conda environment

conda env create -f environment.yml
activate sentinel-tools

You may run the tests to verify that it is working properly

coverage run -m s2_idgen.test_s2_idgen

This is made for working with Jupyter Lab. You may want to install the current envionment as kernel:

ipython kernel install --user --name=<any_name_for_kernel>

Open Jupyter Lab (and/or perhaps your most favourite python IDE) and have fun!

Do not manually edit the README.md and README.txt as they should be generated from this notebook.

7. Acknowledgements

This python package is developed with support by the Austrian Research Promotion Agency (FFG) under the Austrian Space Application Programme (ASAP) within the project Sen2Cube.at (project no.: 866016).

8. Contact

If you have any questions or inquiry, please open an issue or contact one of:

Dr. Dirk Tiede

Mr. Martin Sudmanns

Ms. Hannah Augustin