GEOLIDAR for the study of surfaces, the biosphere and the hydrosphere

Lidar is a laser remote sensing method used in research and industry to characterize surfaces and the atmosphere. The abbreviation "lidar" stands for "LIght Detection And Ranging", and is modelled on radar, sodar or sonar. The term can be applied to a wide range of instruments, techniques and applications. In practice, lidar covers two main areas of activity, and two distinct communities in terms of how they deal with problems. The "atmosphere" community tends to be made up of research groups, each developing its own instruments and signal processing and data analysis algorithms [ E4310 , E4311 ], while the "surface" community is structured around institutional or private users who call on service companies equipped with industrial lidars and standardized software.

This article deals with geophysical lidars, or geolidars, for land surfaces and planetary exploration. It presents the physics of measurement, methods, instrumentation and applications. First and foremost, lidar uses light's time-of-flight to determine the distance to scattering targets. Distance measurement alone is extremely important for topographic surveys, bathymetry of aquatic environments and geodesy. In addition, measurements of scattered intensity, depolarization of received light and scattered spectrum are used to characterize targets.