Evaluation of the potential of PLEIADES system for 3D city models production : Building, vegetation and DTM extraction

The Pleiades system developed by the French space agency CNES shall be ready for launch in early 2009. It deals with a new generation of high resolution optical satellites. The great agility of Pleiades satellites with their motion capability in roll, pitch, and heading, will allow new acquisition modes which are impossible with SPOT series satellites. Indeed, the system will be able to perform three-fold stereoscopic colour images of 20km swath and 70cm resolution. Several experimentations and simulations are being carried out in order to verify the ability of the system to fulfill the technical and operational requirements of the map-making processes. Last year, a first study has been carried out on 3D city models production on two small areas from simulated images and with a lot of different contexts. Considering the promising results, studies carry on this year, with more different areas and Pleiades simulation images more realistic. Two other topics have been studied: automatic vegetation detection and DTM processing. Concerning building extraction we have used the same production line as last year. Concerning vegetation extraction we tested two methods. The first one is classic: we threshold the Normalized Difference Vegetation Index (NDVI). The second method is more elaborated: it deals with an algorithm which studies the value of texture features and transforms colour spaces for segmentation and classification. For the DTM calculation we have used a method based on elastic grid algorithm. Finally we have integrated all these different necessary primitives (buildings, vegetation and DTM) to produce a complete 3D model on new datatests areas.