Читать книгу Surface Displacement Measurement from Remote Sensing Images - Olivier Cavalie - Страница 12

Philippe DURAND and Stephane MAY

CNES, Toulouse, France

Earth observation satellites have provided images all around the world for more than half a century. Passive optical imaging systems and synthetic aperture radar (SAR) active sensors are nowadays the main sources of information used to derive surface displacement fields. To provide an overview of the images available through space agencies and their main characteristics, this first chapter describes different space missions with data relevant for ground motion displacement measurements. For radar, it is important to observe the field under the same incidence angle, meaning that this may depend upon the satellite orbit housekeeping and general design. SAR missions where orbit is not maintained are not mentioned (except the Iceye mission): their data seem useless at first sight for SAR interferometry (InSAR, see Chapter 4) and probably for SAR correlation algorithms (offset tracking, see Chapter 3). Data access, particularly when free of charge, is also described for the missions.