CNES research and development and available software in the framework of space-images based risk and disaster management

Abstract

CNES has been involved for four years in the so called International Charter space and major disasters. In this framework, both software development and research activities have been carried out, which aim at testing the usefulness of space based images for risk and disaster management, and at improving the space image based products deliverable to the end users. Space images provide unique spatial coverage and potentially high site revisit opportunities. In case of disaster (like fire, flood, earthquak...), comparing images acquired before and after the event is the usual way to extract information about the spatial extension and the magnitude of the disaster. But to perform this comparison, two steps are necessary: coregistration of images and geo-referencing on the terrain. The typical technical problems are the following: First the images are not always geo-referenced, which means not fully superposable to a map, and even when this is the case, geo-referencing is never perfect, because orbital and attitude data are not known with a sufficient accuracy. Second, because we deal with unforeseen events, thus using in the urgency whatever image is available, we may be obliged to use and compare images from different satellite instruments, when no adequate image pair is available from a single satellite. The paper develops the technical issues of co-registration and geo-referencing. It analyses the impact of the local DEM (Digital Elevation Model) quality. It considers both cases of similar and non similar images, like for example an optic image and a radar one. The paper addresses the present status of CNES software for risk and disaster management, pointing out its unique features and also the still missing parts. The current research directions are also presented. © 2005 Springer-Verlag Berlin Heidelberg.