*S, Vol. XXXVIII, Part 7B 
In: Wagner W., Szekely, B. (eds.): ISPRS TC VII Symposium - 100 Years ISPRS, Vienna, Austria, July 5-7, 2010, IAPRS, Vol. XXXVIII, Part 7B 
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PLEIADES-HR IMAGING SYSTEM: 
GROUND PROCESSING AND PRODUCTS PERFORMANCES, 
FEW MONTHS BEFORE LAUNCH 
S. Baillarin 3 , C. Panem 3 , L. Lebegue 3 , F. Bignalet-Cazalet 3 
3 CNES (Centre National d'Etudes Spatiales), 18 avenue Edouard Belin - Toulouse Cedex4 - France - 
simon.baillarin@cnes.fr 
Commission VI, WG VI/4 
KEY WORDS: High resolution, Sensor, Optical, Orthoimage, Mosaic 
ABSTRACT: 
Pleiades-HR is the highest resolution civilian earth observing system ever developed in Europe. This optical imaging project is 
conducted by the French National Space Agency, CNES. It will operate two satellites designed to provide optical images to civilian 
and military users. The first satellite is ready for launch, the second 18 months later. It will allow, in Nadir acquisition conditions, 
to deliver image products 20 km wide, false or natural coloured scenes with a 50 cm ground sampling distance. 
Imaging capabilities have been highly optimized in order to acquire, in the same pass, along-track mosaics, stereo pairs and 
triplets, and multi-targets. To fulfil the operational requirements and ensure quick access to information, ground processing has to 
automatically perform the radiometric and geometric corrections. Since ground processing capabilities have been taken into 
account very early in the mission development, it has been possible to relax some costly on-board components requirements, in 
order to achieve a cost effective on-board/ground compromise. 
Starting from a Pleiades-HR system overview, this paper gives a quick description of the ground segment functional breakdown 
and focuses more precisely on the image processing and associated products. The geometric accuracy is evaluated and the excellent 
results obtained are presented. 
Finally the paper presents the ground segment architecture that will handle this “heavy” processing in the different operational 
Centres. 
1. 1. INTRODUCTION 
Pleiades-HR, the high resolution optical earth observing 
mission developed for both civilian and military users, is under 
qualification tests in CNES and ASTRIUM premises. This 
project consists of two agile satellites that will provide high 
resolution images in Panchromatic (PA) and Multi-Spectral 
(XS) modes with a 50 cm ground sampling distance. This 
system, build up in a European context (partnerships with 
Spain, Sweden, Belgium, Austria and Italy), will be operated 
in a dual context with civilian and defence users. 
Figure 1: Pleiades-HR satellite 
Imaging capabilities have been highly optimized in order to 
acquire several targets, in the same pass, allowing along-track 
image-mosaics, stereo pairs and triplets. To fulfil the 
operational requirements and ensure quick access to 
information, ground processing has to perform automatically 
radiometric and geometric corrections. 
First, this paper offers an overview of the image processing 
system and the products definition. Then the main system 
products are detailed and their quality assessed. Finally, the 
image processing architecture is briefly presented. 
2. FROM SYSTEM TO PRODUCTS DEFINITION 
2.1 Overview 
From a ground segment point of view, Pleiades-HR 
architecture is defined as a classical “image-mission” loop: the 
User Ground Centres (also called UGCs; there are 3 different 
UGCs: French and Spanish Defence UGCs and French Civilian 
UGC) gather the different users acquisition requests, 
optimizing the satellite resource, and prepare the dual work 
plan which is finally sent by the Control Centre to the satellite, 
3 times per day. After sensing, the acquired data-strips are 
downlinked over the receiving stations (with respect to the 
work plans) and the image telemetry is automatically 
inventoried and archived in each UGC. 
Then, each UGC manages the image production requests 
coming from authorized users and process accordingly the 
archived telemetry to generate the requested product. The 
delay between the end of the reception and the product delivery 
is less than one hour. 
The ground processing has also been designed to be highly 
interoperable; to allow federations with other earth observation 
systems in the GMES context. Hence, data format (catalogued