First delivery of Venµs images

A first set of 35 images (L1C) is available for download on the following CNES web site:

https://theia.cnes.fr

The Delta of Ebro

 Venµs is now systematically acquiring data on all selected sites since January 2018, although a few acquisitions were missed from time to time for various technical reasons, which should become progressively less frequent. The commissioning phase of the Venµs mission is not yet completed regarding image quality (radiometry and geometry). This delay is due to several issues, the most important of which are detailed hereafter. However, since these issues do not prevent the use of the data, CNES decided to process and distribute a first set of 35 Level-1 (L1) images for which the radiometric and geometric qualities are acceptable. Level 1 corresponds to orthorectified Top of the Atmosphere reflectances. This preliminary data set is intended to allow the users to familiarize with the data and their format. These 35 images are only a subset of the data that are systematically acquired over the Venµs sites since January 2018. We plan to start the distribution of these L1 Venµs time series by April 2018. We expect to start the distribution of the Level-2 products (surface reflectances) by late May or beginning of June, 2018.

 

 Main issues

 

  1. The absolute calibrations of the spectral bands B1 (415 nm) and B2 (440 nm), both located in the blue, are less accurate than the calibration of the other spectral bands. This issue prevents the use of B1 and B2 for retrieving the aerosol optical depth (AOD) or for water color applications.
  2. The accuracy of the satellite attitude restitution is for now lower than expected. Due to the fact that the different bands are not acquired simultaneously this has mainly impacts on the inter-band registration. For some sites with heavy cloud cover or uniform landscape, this issue also impacts the multi-temporal registration.

 

The characterization of radiometric and geometric performances is still ongoing. Efforts are also devoted to the improvement of the preprocessing algorithms.As soon as significant progresses are made, the whole data set acquired since January 2018 will be reprocessed with the new parameters and algorithms.The product format document is available here. A more complete version will soon be made available there.

 

The Venµs page on the Theia web site will keep you informed on the progress made. 

 

 

 

 

 

Plus d'actualités

Copernicus should keep S2A operational after S2C launch

The launch of Sentinel-2C (S2C) is scheduled on the 4th of September 2024, next week ! After 3 months of commissioning phase, S2C will replace S2A, to fulfill the Sentinel-2 mission together with S2B. S2B will later be replaced by S2D. The current plans are to keep S2A as a redundant satellite, in case something […]

Fin de la phase d’acquisitions d’images de VENµS

 => C’est avec une certaine tristesse mais aussi beaucoup de fierté que je vous rappelle que la phase opérationnelle de VENµS se terminera fin juillet après 7 ans de bon travail. La phase d’acquisition actuelle (VM5) s’arrêtera le 12 juillet. Les semaines restantes seront consacrées à quelques expériences techniques (les acquisitions au-dessus d’Israël se poursuivront […]

The end of VENµS imaging phase

=>  It is with some sadness but also a lot of pride that I remind you that the VENµS operational phase will end at the end of July after 7 years of good work. The current acquisition phase (VM5) will stop on the 12th of July. The remaining weeks will be devoted to a few […]

Rechercher