The Kalideos Databases: A Framework for the Scientific Analysis and Exploitation of Sentinel Images
Rabaute, Thierry1; Lafrance, Bruno1; Imbo, Patrick1; Selle, Arnaud2
1CS Systèmes d'Information, FRANCE; 2CNES, FRANCE
The Kalideos programme was born in 2001 from the CNES will to support research in remote sensing through the development of "reference remote sensing databases". Such databases aim at providing researchers with time series of multi-sensors and multi-resolution remote sensing imagery.
Up to now, four reference datasets have been developed over multi-thematic sites of about 50 x 50 km2:
The basic principle of the Kalideos databases consists in gathering satellite images and accurately preprocess them in order to provide temporally consistent datasets, along with exogenous data (maps, physical parameters, land use information, in-situ measurements...):
The optical datasets integrated in the databases are essentially made of Spot and Formosat imagery, but QuickBird and GeoEye products are also available in some cases. Concerning SAR data, most of the information comes from ERS, Envisat and, more recently, TerraSAR-X sensors, but a few Radarsat data can also be retrieved.
The Kalideos databases are then disseminated towards the scientific community through a common dedicated Web portal (http://kalideos.cnes.fr), from where image time series can be retrieved on a free basis, provided applying scientists have requested a protected access granted by CNES and that they limit the use of the data only to research purposes. This portal supplies all the information requested to join the Kalideos network and gives short descriptions of the most significant achievements of the programme and indications about the contributing scientific teams. Moreover, it offers access to documentation supplied by the involved researchers as a feedback from their work (scientific papers, presentations, technical reports, relevant Web links...).
One of the key issues of the Kalideos programme is that the databases have now turned into focal points for the development or the improvement of Earth observation based applications, as well as the assessment of recently launched or future sensors with regard to thematic issues. As a consequence, some of the corresponding sites have been selected as priority test areas for the thematic in-flight commissioning activities of the Pleiades system. They are also among the test sites considered for the Spot 4 Take Five experiment initiated by CNES late January to supply researchers with Sentinel-2 precursor imagery during a few months.
Looking at the variety of data available, it can be considered that the Kalideos programme has been anticipating full and open access to "GMES like" Earth observation data for scientists since 2001. Indeed, among the GMES spatial infrastructure, Sentinel-1 and Sentinel-2 are particularly awaited by the Kalideos community to get high resolution high frequency SAR or optical data in order to perform temporal analysis of several phenomena like crop systems, forest, vegetation phenology, soil moisture...
After an overview of the current status and content of the Kalideos databases, some examples of use of these scientific reference datasets will be presented and discussed. Indications about the potential integration of Sentinel-1 and Sentinel-2 data and their use for scientific analysis will also be given.