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 […]

Applications

Impact du COVID-19 sur la pelouse du Centre Spatial de Toulouse

Le CNES a publié sur LinkedIn ces jolies photos du Centre Spatial de Toulouse après le confinement. Grâce aux satellites d’observation de la Terre, les ingénieurs du CNES sont capables d’étudier la végétation aux quatre coins du globe. Mais, les cordonniers sont souvent les plus mal chaussés… Pourraient-ils étudier leur propre pelouse par satellite ? […]

In English

Debris flow in the Ishkoman Valley

In July 2018, the Pamir Times has reported that a lake formed due to a debris flow in the Ishkoman Valley, Pakistan. This event caused the destruction of dozens of housed in Badswat and Bilhanz villages. The flood debris running down the slope hit the mountain on the opposite side, and formed a barrier, blocking […]

Applications

Benefits of SAR for forest loss alert detection in the tropics

The tropical forest is an important carbon sink which also hosts high biodiversity. Monitoring forest loss is therefore a major issue which requires efficient and accurate tools. In fact, the major challenge is to detect forest loss as precisely and quickly as possible, despite cloud cover which limits the availability of usable optical satellite imagery. […]

In English

Chaos theory, Rössler cake and satellite remote sensing

Chaos theory, Rössler cake and satellite remote sensing A chaotic attractor was obtained from satellite remote sensing data for the first time in 2011 giving a strong argument for chaos in real environment. This result has a special sound today May 20th 2020, since it is the 80th birthday of Otto E. Rössler — one […]

Code

Towards a composite of the most recent clear-sky observations from the Theia Snow collection

We are thinking of a new « live » product which would allow anyone to display the most recent snow observations from Sentinel-2 in a web browser. This service would simply display a composite of the latest Theia Snow products over a given time window (e.g. the past 20 days). This can be easily coded thanks to […]