Sentinel-2

A first peek at new Sentinel2 geometric processing

=> If you are working with Sentinel2 products, you probably heard that ESA new geometric processing is active since 1st of April 2021. This new processing, based on the geometric refinement of viewing parameters with respect to a Global Reference Image (GRI), should bring absolute location error from 11 meters (95.5% of products) to better […]

05.05.2021

2 000 downloads for MAJA !

The distribution of MAJA L2A processor, as an  executable software, started in april 1997, but we started counting the number of downloads only since October 2017. The cumulative number of downloads just reached 2000 on April the 2nd 2021. It is on average 1.56 downloads per day, and more than 2 downloads per work day […]

14.04.2021

Can surface reflectance be negative ?

=> Here is a frequently asked question : I noticed, in such L2A product processed by MAJA, that some pixels had negative reflectances, is it normal ? No, it should not happen, but the fact it happens is not entirely surprising, I will explain it below. Unlike negative reflectances, reflectances greater than one can exist, […]

06.04.2021

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, […]

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

Le glacier de l’Astrolabe s’apprête à vêler un bel iceberg

Sur une image Pléiades acquise le 15 janvier, Etienne a remarqué une fracture qui traverse une bonne partie de la langue du glacier de l’Astrolabe auprès de la base Dumont-d’Urville en Antarctique. On peut reconstituer l’ouverture de cette crevasse à partir d’une série d’images Sentinel-1 (une année complète de janvier 2020 à janvier 2021) D’après […]

22.01.2021

Crop Irrigation, a new project labeled by the Space Climate Observatory

=>  The Space Climate Observatory (SCO) is an international initiative of the One Planet Summit, launched in June 2019, which is also a French initiative. The SCO brings together several space agencies around the world and international organizations (UNDP, ESA, UNEP). It aims at developping projects for local decision-makers to help them adapt to climate […]

20.01.2021

Irrigation Grandes Cultures, un nouveau projet labellisé par l’observatoire spatial du climat

=> L‘ Observatoire Spatial du Climat (SCO pour Space Climate Observatory) est une initiative internationale du One Planet Summit, lancée officiellement en Juin 2019, à l’initiative de la France. Cette initiative regroupe des agences spatiales du monde entier et des organisations internationales (PNUD, ESA, PNUE). Elle a pour vocation de développer des projets à destination […]

Free and open data: fine, but who pays for the processing?

In the previous post, Olivier advocated for the open data policy in remote sensing. Although Oliver is facing some actual resistance because the Sentinel-HR mission would step on the toes of industrial champions, my feeling is that there is now a large consensus on this issue. The economic and social benefit of the open data […]

21.12.2020

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