Airborne laser scanning (ALS) systems allow a direct and illumination-independent measurement of 3d objects in a fast, remote and accurate way. Beside basic range measurements, the current commercial ALS developments allow to record the waveform of the backscattered laser pulse. Latest trends in sensor developments focus on single-photon detection. Airborne Laser Scanning (ALS) for instance is used for capturing large-scale 3D environments with almost homogeneous point density with a local point density of typically 4-100 pts/m^2. Therefore, different applications are of interest, like urban planning, change detection, forestry surveying, or power line monitoring. Further to describe the 3D scene, products like digital terrain models (DTMs), digital surface models (DSMs), or city models are provided.