Towards the Pleiades Thematic Commissioning Phase

The Pléiades program is a dual program developed in cooperation between the space agencies of France, Sweden, Belgium, Spain and Austria. It has been designed to provide high resolution optical data for the benefits of civilian and defence users in term of operational capacity, rapid access and protection of defence interests. The space component is composed of two "small satellites" (mass of one ton) offering a spatial resolution at nadir of 0.7 m and a field of view of 20 km.

Their great agility enables 1) a daily access all over the world, which is a critical need for defence and civil security applications, and 2) an high coverage capacity necessary for cartography applications. Moreover, to meet the needs for detailed mapping, specially in urban areas and to complement aerial photography, Pléiades will offer instantaneous stereoscopic acquisition and the capability to cover large areas by acquiring collateral stripes in the same path.

Beside the Pléiades system developments, an extended accompaniment program has been operating since 2004, to prepare, accompany and promote the future exploitation of the Pléiades images. The objectives of this program are 1) to assess the thematic capability of the Pléiades system to produce the various services required by end-users for distinct thematics (defence, risks, cartography, hydrology, forestry, agriculture ...) and 2) to develop efficient tools to facilitate image information extraction by end-users.

The Thematic part of the accompaniment program covers a large range of applications (civil and defence ones), and aims at specifying and validating value added products and services required by end users. An in-depth work of user needs assessments in eight thematic domains (sea and coastline, risks and humanitarian aid, cartography and town planning, geophysical hazards, hydrology, forestry, agriculture and defence) has given rise to a large number of feasibility studies. This part includes consideration about products integration in the operational systems or processing lines and a careful thought on intermediary structures to be developed to help “on the field end users”. Lastly, this part aims at raising future users awareness, through practical demonstrations and validations.

The Methodological Part of the accompaniment programme aims to prepare and accompany the use and the exploitation of the sub-metric images, both optical and radar. The French Space Agency (CNES) decided to develop the Orfeo Toolbox (OTB), a set of algorithmic components capitalising the methodological know how and its generic applicative tool Monteverdi. OTB/Monteverdi is distributed as an open source library of image processing algorithms. It is distributed under a free software licence CeCILL (similar to GPL) to encourage contribution from users and to promote reproducible research. The library is intensively tested on several platforms as Linux, Unix and Windows.
Functionalities are also adapted to process huge images using streaming and multi-threading as often as possible. Among other, OTB provides a number of heavily documented functionalities as image access, filtering, feature extraction, image segmentation; classification; change detection; GIS links; ….

After a brief description of the Pléiades system, this paper will present the first results obtained in the accompaniment program and the organisation of the Pléiades Thematic Commissioning phase, to be performed during the first year of Pléiades life.