In partnership with the European Commission and in the frame of the Global Monitoring for Environment and Security
(GMES) program, the European Space Agency (ESA) is developing the Sentinel-2 optical imaging mission devoted to
the operational monitoring of land and coastal areas.
The Sentinel-2 mission is based on a satellites constellation deployed in polar sun-synchronous orbit. While ensuring
data continuity of former SPOT and LANDSAT multi-spectral missions, Sentinel-2 will also offer a wide range of
improvements such as a global coverage, a large field of view (290km), a high revisit capability (5 days with two
satellites), a high resolution (10m, 20m and 60m) and multi-spectral imagery (13 spectral bands). In this context, the
Centre National d'Etudes Spatiales (CNES) supports ESA to define the system image products and to prototype the
relevant image processing techniques.
First, this paper presents the Sentinel-2 system and the image products that will be delivered: starting from raw
decompressed images up to accurate ortho-images in Top of Atmosphere reflectances. The stringent image quality
requirements are also described, in particular the very accurate target geo-location.
Then, the prototyped image processing techniques will be addressed. Both radiometric and geometric processing will be
described with a special focus on the automatic enhancement of the geometric physical model involving a global set of
Finally, the very promising results obtained by the prototype will be presented and discussed. The radiometric and
geometric performances will be provided as well as the associated computing time estimation on the target platform.
In the framework of the Global Monitoring for Environment and Security (GMES) programme, the European Space
Agency (ESA) in partnership with the European Commission (EC) is developing the SENTINEL-2 optical imaging
mission devoted to the operational monitoring of land and coastal areas. The Sentinel-2 mission is based on a twin
satellites configuration deployed in polar sun-synchronous orbit and is designed to offer a unique combination of
systematic global coverage with a wide field of view (290km), a high revisit (5 days at equator with two satellites), a
high spatial resolution (10m, 20m and 60 m) and multi-spectral imagery (13 bands in the visible and the short wave
infrared spectrum). SENTINEL-2 will ensure data continuity of SPOT and LANDSAT multispectral sensors while
accounting for future service evolution.
This paper presents the main geometric and radiometric image quality requirements for the mission. The strong multi-spectral
and multi-temporal registration requirements constrain the stability of the platform and the ground processing
which will automatically refine the geometric physical model through correlation technics. The geolocation of the
images will take benefits from a worldwide reference data set made of SENTINEL-2 data strips geolocated through a
global space-triangulation. These processing are detailed through the description of the level 1C production which will
provide users with ortho-images of Top of Atmosphere reflectances. The huge amount of data (1.4 Tbits per orbit) is
also a challenge for the ground processing which will produce at level 1C all the acquired data.
Finally we discuss the different geometric (line of sight, focal plane cartography, ...) and radiometric (relative and
absolute camera sensitivity) in-flight calibration methods that will take advantage of the on-board sun diffuser and
ground targets to answer the severe mission requirements.