Composite (3A)

Les séries temporelles de niveau 3A de Sentinel-2

=> Le centre de données Theia a produit en début de semaine la synthèse mensuelle des données Sentinel-2 pour le mois de juillet 2020 (avec nos chaines WASP et MAJA). Pour la troisième année consécutive, celle-ci est sans nuages et montre une forte sécheresse. Et celle-ci s’est probablement aggravée au cours du mois d’août.   […]

In English

[MUSCATE News] Theia production is stalled (solved)

Update (18/08/2020): all the issues have been corrected, MUSCATE production and distribution have resumed. Update (17/08/2020):  production has resumed, but it will take us a couple of days to catch the backlog up.  The download site is still offline, but this should be solved quickly.   Following the failure of an equipement which hosts the […]

En Français

Pic Saillant : la balade hydrologique du dimanche

En partant de Boutx (780 m) on peut monter au Pic Saillant (1756 m) (voir le topo) et admirer un magnifique panorama hydrologique sur le haut bassin de la Garonne et de son affluent la Pique. Par temps clair, on peut deviner les sommets du Luchonnais encore enneigés au mois de juillet qui marquent la […]

En Français

Sortie du bulletin Theia n°13

Le 13e bulletin Theia est sorti, un grand merci à Isabelle Biagiotti !

BRDF

[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 […]

BRDF

[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 […]

BRDF

[Directional effects] simple BRDF normalization

Introduction To perform a correction of directional effect, directional models are required. A large number of directional models have been developed, such as the ones of Roujean [1] or Ross-Li [2], that try to reproduce the directional variations as a function of viewing angles and solar angles, with a rather good accuracy for most types […]

En Français

[Directional effects] Effects of crop orientation on surface reflectance

Introduction In the framework of our research for ESA concerning the maximum field of view of next generation of Sentinel-2 satellite, we searched for a way to estimate directional effects, without using a particular directional model to correct for these effects. The current directional models are imperfect, and we can assume that progress will be […]

BRDF

[Directional Effects] Validation of DART simulations of vineyards using VENµS multi-angular observations

Question: The color image displayed on the left is a new kind of RGB composite image, can you guess how it was made ? Hints: the blue bright pixels correspond to water, but water is not bright usually… except if it is obtained in specular condition, when the water surface mirrors the sun towards the […]