Generate Digital Elevation Models Using Laser Altimetry (LIDAR) Data

A Laser Altimetry (LIDAR) system aboard an aircraft can yield highly accurate data about the ground surface and vegetation below. Raw LIDAR points must be processed to generate a digital elevation model (DEM), i.e. a digital map of the terrain surface. A number of techniques can be used to generate the DEM, and in this report I investigate several of these including a new algorithm based on recovering the lower envelope of a signal using amplitude demodulation. The default and most widely used technique consists of a series of thresholds based on local mean and variance measures. The amplitude demodulation technique runs much faster than the default technique and should be robust for flat and varying ground surfaces. Visual inspection of the entire image suggests that the amplitude demodulation technique achieves good results.