The arrival of airborne Lidar, also referred to as airborne laser scanning (ALS), has revolutionized area-wide 3D data acquisition of topography, bathymetry, vegetation, buildings and infrastructure. This article presents an overview of the tremendous progress made since then in both sensor and aircraft technology. Current trends include a steady increase of the measurement rate, achievements in full waveform processing, the spread of multispectral and topo-bathymetric laser scanners, the introduction of single-photon sensitive airborne sensors... (read more)