Venµs captured the orange snow in the Pyrenees

Theia just published the first Venµs images today, including a beautiful view of the Pyrenees. Once you have dezipped/untared/unzipped the files you can make a true color composite using the command:

gdal_translate -b 7 -b 4 -b 3 -scale 0 300 0 255 -ot byte VE_VM01_VSC_PDTIMG_L1VALD_ES_LTERA_20180419.DBL.TIF myColorCompo.tif

I tend to focus on the snow so I stretched the colors between reflectances 0-1000 instead of 0-300:

gdal_translate -b 7 -b 4 -b 3 -scale 0 1000 0 255 -ot byte VE_VM01_VSC_PDTIMG_L1VALD_ES_LTERA_20180419.DBL.TIF mySnowColorCompo.tif

First, I was a bit puzzled by the orange shade in the northern part of the image. We inspected carefully the image with Olivier because at this stage radiometric calibration issues are still possible..
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Theia started the distribution of Venµs products in Near Real Time


Great news for our little Venµs satellite project: Theia has started distributing Venµs L1C data in near real time. The data acquired yesterday are already available on https://theia.cnes.fr

 

 

These L1C products are tagged with 0.9 version, which means that their quality is not as good as what we think we will be able to deliver in a couple of months. The multi-spectral and multi-temporal registration can still be improved, even if it is not too far from our expectations yet in most cases. The image quality teams are finishing an error budget of the current situation, and also preparing the improvement with our Israeli partner who manage the satellite.  We will tell you about that.

 

The L2A delivery will also start in a few weeks, but the L1C teams, who had much more work than expected with this satellite, handled us correct products very late, and we still need to tune a few parameters to provide good quality products.

 

On the Theia website, you will find several ways to download the tiles. My little download tool has also been updated. Once you have registered, and updated the config.cfg file, you will be able to download at once all the products in Australia with the following command line :

python theia_download.py -l 'Australia' -c VENUS -a config.cfg -d 2018-01-01

The data format is explained here. Its packaging with useless zips and tars is still provisional and will be simplified very soon.

 

 

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

 

Venµs is now systematically acquiring data on all selected sites since January 2018, although a few The Delta of Ebroacquisitions 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.

 

Time series of Venµs images acquired over Oklahoma (USA) and processed at level 2A (with a first try of atmospheric effects correction applied)

 

 

 

 

 

Venµs mission status, 5 months after launch

Hereafter some news on the status of the Venµs mission.

Venµs was successfully launched from the Kourou space port on August 1st by a VEGA launcher:

 

https://vega.cnes.fr/en/live-vega-launch-venus-august-first-2017

 

First images were acquired by mid-August (see below for examples). The commissioning phase is still running. This phase consists in checking the whole system, including the satellite, the camera, the download of the images and data to the Kiruna receiving station, the ground processing chains, as well as the geometric and radiometric calibrations. All these components are in a good health and working well. However, given the very demanding requirements in terms of multitemporal registration, more work than anticipated is needed to fine tune the AOCS (Attitude and Orbital Control Subsystem) and the processing algorithms. In addition, the first part of the in-flight demonstration of the electric engine developed by RAFAEL (called IHET) will take place from mid-december to mid-january.

 

For these reasons, CNES and ISA plan to resume the systematic acquisitions of the scientific sites early 2018. Preparing the reference images for every site and checking the quality of time series will also take some weeks. We anticipate delivering the Level 1 (top of the atmosphere reflectances, orthorectified) products by april 2018, but all the data acquired from the beginning of systematic acquisitions will be processed and made available on the Theia web site:

http://www.theia-land.fr/en/products/venus

 

Level 2 data (top of the canopy reflectances) might be available slightly later since the method we use requires a time series of data.

You will find some examples of images following the links below :

 

https://presse.cnes.fr/en/france-israel-space-cooperation-venus-vegetation-monitoring-satellite-sends-back-first-images

and here:

 

http://www.cesbio.ups-tlse.fr/multitemp/?p=11215

http://www.cesbio.ups-tlse.fr/multitemp/?p=11096

http://www.cesbio.ups-tlse.fr/multitemp/?p=11344

 

The Moon is also acquired for calibration monitoring purposes:

http://www.cesbio.ups-tlse.fr/multitemp/?p=11344

 

We thank you for your patience. We are doing our best to provide you with quality products.

Happy New Year to you all

Venµs à l'honneur en Haute-Garonne et en Ariège en 2018

Le satellite Franco-Israelien Venµs, attendu depuis si longtemps, a été lancé le 2 août 2017. 110 sites dans le monde vont être observés en 2018 et 2019 à 10 m de résolution et avec 12 bandes spectrales. Alors que la plupart des sites ne correspondent qu’à l’emprise d’une scène Venµs (27 à 32 km de large (est-ouest) * 27 km nord-sud), le site ‘Toulousain’ couvre un transect de 168 km du nord de la Haute-Garonne (Grenade) jusqu’en Espagne, en passant par les Pyrénées ariégeoises (dont le Mont Vallier), prolongé par un 2ème transect de 157 km de long en Espagne jusqu’à l’embouchure de l’Ebre (carte en ligne).

 

L’intérêt d’avoir choisi un si grand transect est la grande diversité des conditions pédo-climatiques due au relief varié de la zone, des types de cultures et de végétation et enfin de pratiques humaines de gestion (type d’agriculture, d’élevage…), sur un nombre de kilomètres assez restreint. Ce transect Venµs permettra ainsi d’étudier de nombreux agro-écosystèmes différents.

Le transect Venµs, de Toulouse à l'espagne.

L’intérêt majeur de la mission scientifique Venµs est d’offrir une très forte revisite temporelle : chaque site sera observé tous les 2 jours. En combinant les données de Venµs avec celles de Landsat 8 et Sentinel-2, la revisite sera presque quotidienne. Au niveau scientifique, il s’agit de préparer les futures missions spatiales opérationnelles et de démontrer l’intérêt d’une fréquence temporelle très élevée. Au niveau thématique, ces 2 années 2018 et 2019 vont permettre de suivre finement les évolutions rapides des phénomènes naturels comme les variations du manteau neigeux, la croissance des cultures, les stades phénologiques des diverses végétations (forêts, prairies, cultures, autres milieux naturels), etc… Pour être pleinement valorisés, ces sujets nécessiteront des observations de terrain de qualité sur ces deux années 2018 et 2019. Nous faisons donc acte d’information, voire d’appel à volontaires, pour collecter des données de terrain pertinentes. Ci-dessous, nous listons les principaux sujets déjà prévus ou potentiels, pour chacune des 2 grandes zones géographiques du transect ; ainsi que les principaux acteurs pré-identifiés.

 

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Venµs' moon

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Well, the audience of our blog is still steady increasing, there is no need to use explicit titles to get more connexions. And although I mainly use space to look down, I do not think the planet has a natural satellite. So why this title ?

The Venµs satellite actually showed us the moon, and not only to provide a nice title in this blog. Our Israeli colleagues from MBT really worked hard to obtain it, as a very good pointing accuracy is needed to image it from a quickly rotating satellite : the moon is far from here !

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Quand Venµs nous montre la lune

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Non, non, la fréquentation de ce blog n'est pas en baisse au point qu'il nous faille attirer une nouvelle clientèle pour compenser une perte de revenus financiers issus de la publicité. (La fréquentation augmente régulièrement d'ailleurs, mais les revenus financiers sont nuls...)

Le satellite Venµs nous a vraiment montré la lune, et ce n'est pas seulement pour proposer une belle image et un titre accrocheur sur le blog du CESBIO. Nos collègues israéliens de MBT se sont d'ailleurs donné beaucoup de peine pour l'obtenir, car il faut une très bonne précision de pointage pour l'observer : la lune est loin !

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The Delta of the Ebro seen by Venμs

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The Delta of Ebro

Delta of the Ebro observed by Venμs on August 18, 2017 (Copyright CNES 2017)

The Ebro (Iberus in Latin) flows into the Mediterranean in Catalonia after a journey of more than 900 km from its source in Cantabria. The current morphology of the Delta results from the significant increase in sediment inputs caused in the 15th century by the intensive deforestation of the river catchment: the conquest of the Americas required the construction of boats. It was at this time that the land emerged over the sea, making the delta this wide plain of which only 10% of the land culminates at more than 2 meters. The construction since 1930 of 187 upstream dams reduces the sediment flow (from 28 Mt / year to about 0.1 Mt / year), which partly explains the erosion currently observed in some parts of the delta.

 

80% of the area of ​​the delta is devoted to crops, mostly rice producing one-third of the country's production. The rest, protected by the Natural Park, consists of lagoons, reed and rush beds,  brackish marshes and sandbanks.

 

The Delta de l'Ebre is included in one of the sites that will be observed by Venμs every two days for two and a half years. It is part of ClimaDat, a long-term climate research network. Different issues will be adressed: land use, phenology, greenhouse gas fluxes (CO2, CH4, N2O), vegetation productivity, role of saline inputs.

 

Complement: the evolution of the Ebro delta from the 4th century:

http://geographyfieldwork.com/EbroEvolution.htm

 

 

Le Delta de l'Ebre vu par Venµs

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Delta de l'Ebre

Delta de l'Ebre observé par Venµs le 18 août 2017 (Copyright CNES 2017)

L’Ebre (Iberus en latin) se jette dans la Méditerranée en Catalogne après un parcours de plus de 900 km depuis sa source en Cantabrie. La morphologie actuelle du Delta résulte de l'augmentation significative des apports de sédiments provoquée au XVe siècle par le déboisement intensif du bassin versant du fleuve : la conquête des Amériques nécessitait la construction de bateaux. C'est à cette époque que les terres émergées ont gagné sur la mer, faisant du delta cette large plaine dont seulement 10 % des terres culminent à plus de 2 mètres. La construction depuis 1930 de 187 barrages en amont réduit le flux de sédiments (de 28 Mt/an à 0,1 Mt/an environ), ce qui explique en partie l’érosion actuellement observée dans certaines parties du delta.

 

80 % de la superficie du delta sont consacrés aux cultures, en majorité de la riziculture qui produit le tiers de la production du pays. Le reste, protégé par le Parc naturel, est constitué de lagunes, roselières, jonchères, marais saumâtres et bancs de sable.

 

Le Delta de l’Ebre est inclus dans l’un des sites qui sera observé par Venµs tous les deux jours durant deux ans et demi. Il fait partie du réseau ClimaDat, un réseau de recherche à long terme sur le climat. Différents thèmes seront abordés : occupation du sol, phénologie, flux de gaz à effet de serre (CO2, CH4, N2O), productivité de la végétation, rôle des entrées salines.

 

Complément : l'évolution du delta de l'Ebre depuis le 4ème siècle :

http://geographyfieldwork.com/EbroEvolution.htm

 

 

Les premières images de Venµs

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Les vrais produits du nouveau satellite Venµs seront des séries temporelles d'images de la terre (pas la planète Venus), acquises tous les deux jours sur plus de 100 sites. Mais pour obtenir ces séries temporelles, il faut que Venµs soit sur son orbite nominale, qu'il rejoindra courant septembre. Mais nous sommes déjà très heureux de partager avec vous les premières images prises par le satellite, pour vous montrer que la caméra, la mémoire et la transmission marchent comme prévu ! C'est déjà beaucoup, et après les habituels debuggages, vérifications, caractérisations et étalonnages, nous recevrons bientôt nos séries temporelles !

L'une des premières images acquises par Venµs, au dessus de Phoenix (Arizona, USA), sur laquelle on peut observer de nombreuses parcelles agricoles irriguées.

 

 

Mais je ne devrais pas trop en dire, alors que le CNES a publié un communiqué de presse officiel , pour lequel chaque mot a été pesé, discuté et approuvé.

Un grand merci à tous ceux qui, en France et en Israël, ont contribué à cette rapide et heureuse publication !