Level 2 Processing System

The FORCE Level 2 Processing System (FORCE L2PS) generates harmonized, standardized, geometrically and radiometrically consistent Level 2 products with per-pixel quality information, i.e. Analysis Ready Data (ARD).

For a description of the method, please refer to the Publications, especially

• http://doi.org/10.3390/rs11091124

• http://doi.org/10.1109/TGRS.2016.2530856

• http://doi.org/10.1016/j.rse.2018.04.046

• http://doi.org/10.3390/rs10020352

• http://doi.org/10.3390/rs11030257

L2PS pulls each enqueued Level 1 image and processes it to ARD specification. This includes cloud and cloud shadow detection, potentially co-registration, radiometric correction and data cubing.

Each image (box in Figure 1) is processed independently using multiprocessing and optionally multithreading. The pipeline is memory resident to minimize input/output (I/O), i.e. input data are read once, and only the final, gridded data products are written to disc. The data generated with this module are the main input for the Higher Level component.

Figure 1. FORCE Level 2 Processing System (L2PS) workflow.

FORCE L2PS consists of two main executables, and a wrapper script that acts as a bridge between them. For the majority of users, it is recommended to use force-level2. However, for specific purposes (e.g. testing/debugging, or if you want/need to implement your own job scheduler), the expert user may want to use force-core or force-wrapper directly.

force-level2	force-l2ps_	force-l2ps

A glimpse of what you get:

Figure 2. Data Cube of Landsat 7/8 and Sentinel-2 A/B Level 2 ARD. A two-month period of atmospherically corrected imagery acquired over South-East Berlin, Germany, is shown here.