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In the frame of the Copernicus program of the European Commission, Sentinel-2 is a constellation
of 2 satellites on a polar sun-synchronous orbit with a revisit time of 5 days (with both satellites), a
high field of view - 290km, 13 spectral bands in visible and shortwave infrared, and high spatial
resolution - 10m, 20m and 60m. The Sentinel-2 mission offers a global coverage over terrestrial
surfaces. The satellites acquire systematically terrestrial surfaces under the same viewing conditions
in order to have temporal images stacks. The first satellite was launched in June 2015 and the
second in March 2017.
In cooperation with the European Space Agency (ESA), the French space agency (CNES) is in
charge of the image quality of the project, and so ensured the CAL/VAL commissioning phase
during the months following the launch. This cooperation is also extended to routine phase as
CNES supports European Space Research Institute (ESRIN) and the Sentinel-2 Mission performance
Centre (MPC) for validation in geometric and radiometric image quality aspects, and in Sentinel-2
Global Reference Image (GRI) geolocation performance assessment.
This paper points on geometric image quality on Sentinel-2B commissioning phase. It relates to the
methods and the performances obtained, as well as the comparison between S2A and S2B. This
deals with geolocation and multispectral registration. A small focus is also done on the Sentinel-2
GRI which is a set of S2A images at 10m resolution covering the whole world with a good and
consistent geolocation. This ground reference leads to ensure an accurate multi-temporal
registration -on refined Sentinel-2 products over GRI- which is also presented in this paper.
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