Development of a LiDAR derived digital elevation model (DEM) as Input to a METRANS geographic information system (GIS).

This report describes an assessment of digital elevation models (DEMs) derived fromLiDAR data for a subset of the Ports of Los Angeles and Long Beach. A methodologybased on Monte Carlo simulation was applied to investigate the accuracy of DEMsderived from the LiDAR data using different interpolation methods (inverse distanceweighted, spline and Kriging) at different grid cell resolutions (0.25m2, and 0.50m2, 1m2and 2m2). Results indicate that elevation accuracy and the accuracy of a buildingfeature derived from the interpolated elevations are not correlated. Inverse DistanceWeighed at 0.25m2 resolution produced the most accurate surfaces and ranked secondin its ability to capture the shape of the building. However, this interpolation method andgrid cell resolution pair took the longest time to compute (over three weeks for theaccuracy simulation). The methodology provides Port personnel and LiDAR users withan approach to determine an appropriate grid cell resolution and interpolation methodfor generating DEMs and extracting building features from LiDAR data. Results indicatethat compromises between surface accuracy, shape representation and the timerequired to process the data are required