High-precision DEM production in complex urban area using LiDAR data

A workflow for high-precision digital elevation model (DEM) production under complex urban environment was proposed in this paper. Firstly, outliers which were far above or below the terrain surface would be removed according to a threshold compared to surrounding points. Secondly, progressive TIN densification method was used to separate ground points from non-ground points. However, there might be some errors that manual filtering was needed to correct the misclassified points. For the area where there was absent of points, interpolation would be controlled with the help of existing survey data (break line, building boundary, etc.). Finally, all ground points were used to interpolate a 1m by 1m DEM and accuracy of the DEM was evaluated. Meanwhile, how to improve the accuracy of DEM under four typical complex situations in the urban area, i.e., overpass, complex buildings, underground park entrance, steep slope, was discussed.