3.6. Methodology

Version 3.2 by Wai-Tim Ng on 2018/08/06 10:50

Index

  • Aggregations
  • Resampling
Aggregation computes new values from sets of values that are uniquely assigned to groups. It involves a grouping predicate (e.g. monthly, 100 m x 100 m grid cells; think of SQL's group_by), and an aggregation function (e.g., mean) that computes one or more new values from the original ones.
Resampling is a broader term where we have data at one resolution, and need values at another (also called scaling). In case we have values at a 100 m x 100 m grid and need values at a 10 m x 10 m grid, the original values will be reused many times, and may be be simply assigned to the nearest high resolution grid cells ("nearest neighbor"), or may be interpolated somehow (e.g. by bilinear interpolation). Resampling from finer to coarser grid by nearest neighbor may again be a special case of aggregation.

Sen2Cor is a Level-2A processor which main purpose is to correct single-date Sentinel-2 Level-1C Top-Of-Atmosphere (TOA) products from the effects of the atmosphere in order to deliver a Level-2A Bottom-Of-Atmosphere (BOA) reflectance product. Additional outputs are an Aerosol Optical Thickness (AOT) map, a Water Vapour (WV) map and a Scene Classification (SCL) map with Quality Indicators for cloud and snow probabilities.

Louis, J., Debaecker, V., Pflug, B., Main-Knorn, M., Bieniarz, J., Mueller-Wilm, U., Cadau, E., Gascon, F., 2016. Sentinel-2 SEN2COR: L2A processor for users. Eur. Sp. Agency, (Special Publ. ESA SP SP-740, 9–13)