Pre-processing (geometry, atmosphere, clouds)

Les réflectances de surface peuvent-elle être négatives ?

=> Voici une question que je reçois assez fréquemment : J’ai remarqué dans (tel produit L2A Sentinel-2 corrigé des effets atmosphériques par MAJA) des réflectances négatives ou égales à zéro. Est-ce normal ? Non, ce n’est pas normal, mais ce n’est pas totalement surprenant non plus. Contrairement aux réflectances négatives, qui ne devraient pas exister, […]

06.04.2021

In Lamasquère, ROSAS has produced its first rosaces

  These space engineers are fast and efficient ! Just a week after our ROSAS station in Lamasquère was erected, we already have the first BRDF measurements, the producing of which required also the processing of calibration sequences. This was done thanks to our colleagues at CNES from the service in charge of measurement physics […]

26.03.2021

Start-up of the new ROSAS station for bi-directional reflectance measurements in Lamasquère

=> At last! We announced it in March 2020, and here it is, one year later! From lock-downs to constraints related to crops grow stages or soil wetness, we have been forced to postpone the operations several times. And finally, the ROSAS* Lamasquère (South-Western France) station sent its very first measurements on March 17, 2021. […]

23.03.2021

Démarrage de la nouvelle station ROSAS de mesure de réflectance bi-directionnelle à Lamasquère

=> Enfin ! Nous vous l’avions annoncé en mars 2020, la voici opérationnelle un an plus tard. De confinements en contraintes liées à l’état des cultures et du sol, nous avons été obligé de repousser les opérations à de multiples reprises. Et finalement, la station ROSAS* de Lamasquère (Haute-Garonne, France) aura fait ses premières mesures […]

Several issues found in recent papers on cloud detection published in MDPI remote sensing

In the last few months, several papers on Sentinel-2 cloud detection have been published by MDPI remote sensing journal. We found large errors or shortcomings on two of these papers, that should not have been allowed by the reviewers or editors. The third one is much better, even if we disagree with one of its […]

11.03.2021

MAJA 4.2 est disponible et devient un logiciel libre.

=> MAJA est un logiciel de détection de nuage et de correction atmosphérique de qualité, développé par le CNES et le CESBIO, avec des contributions du DLR.  Il est codé par CS GROUP. MAJA est utilisé pour traiter les données Sentinel-2 par le Pôle Theia, par les projets Sen2Agriet Sen4cap de l’agence spatiale Européenne, par […]

05.10.2020

MAJA 4.2 is available and open source

=> MAJA is the high quality cloud detection and atmospheric correction code developped by CNES and CESBIO, with contributions from DLR, and coded by CS GROUP. It is used within Pôle Theia, Sen2Agri, Sen4cap, DLR, EEA Snow&Ice, KERMAP… to process #Sentinel2 time series. It’s been a long time since we wanted to make MAJA available […]

01.10.2020

[Directional effects] What field of view for the next generation of Sentinel-2 ?

The European Union is planning a new generation of the Sentinel-2 mission in 2030 or soon after. The main request from users is to improve the revisit frequency from 5 days to 2 to 3 days. There are two ways to improve the revisit: According to ESA and Airbus, the second solution is cheaper, and […]

08.07.2020

[Directional effects] how far can we extend Sentinel-2 field of view ? Conclusions

  This is the final post of a series of studies we did to find out how far we can extend the field of view of next generation of Sentinel-2 satellites. I hope I did not lose most readers in the length of the previous posts. For the readers who land on this page, which […]

Rechercher