Simulation of level 2 with Formosat-2

Tensift data set (Morocco) (animation at better resolution)	Muret data set (Southwest France) (animation at better resolution)
These Images are simulations of VENµS level 2 products, from FORMOSAT2 data sets. These data are orthorectified, registered, calibrated and converted to top of atmosphere reflectance at level 1, then a cloud screening and an atmospheric correction are performed. The cloud screening algorithm also detects cloud shadows, in these images, both clouds and shadows appear in black. Atmospheric correction for these images is not done using the Venµs algorithm described below. An aeronet sunphotometer is present on both sites to obtain Aerosol Optical Properties.

Description of level 2 product

Product Content

For the level 2 products definition, two basic facts have been taken into account:

The Venµs data set will have the following unique features: multi-temporal, high resolution products, with low directional effects. The algorithms to derive bio-physical variables from these data are far from being mature, and it is the aim of Venµs to help develop these algorithms.
The Venµs data set is made of 50 different local data sets on 50 sites located around the world, there is no global data set.

For these reasons, it does not seem relevant to develop very complex biophysical inversion algorithms that will have to work on 50 very different sites with different vegetation characteristics and with different applications. At least for the first generation of Venµs products, it seems more relevant to limit the level 2 processing to what will be common to most applications: cloud screening and atmospheric corrections. If some algorithms developed by Venµs users for their sites seem useful for other users and sites, such algorithms might be added to a second generation of Venµs products.

The Venµs level 2 product will provide:

a refined cloud mask
surface reflectance after atmospheric corrections for all spectral bands (still geolocated)
confidence values
maybe some vegetation indexes

While level 1 is produced at 5 m resolution (we want to preserve all the information for the Level 1 product), the level 2 geometric resolution is 10 m, because the Venµs Signal to Noise Ratio requirements will only be met at 10 m resollution.

Algorithm description

Click on each box for more information