Significance of Altitude and Posting Density on Lidar-derived Elevation Accuracy on Hazardous Waste Sites

This research evaluated the vertical accuracy of two lidar-derived elevation datasets acquired from two different altitudes over a clay-capped hazardous waste site located on the Savannah River Site (SRs), South Carolina, using the same Optech ALTM 2050 lidar sensor and Cessna 337 platform. Both missions provided adequate elevation estimates (low-altitude RmsE z ≈ 6 cm; high-altitude RmsE z ≈ 14 cm.) A quantitative comparison was performed to determine how decreasing platform altitude and increasing lidar posting density affected the vertical elevation accuracy. Higher posting densities did not significantly improve the vertical accuracy of lidar-derived elevation data. Conversely, acquiring the lidar-derived elevation data at a lower altitude had a significant influence on the mean vertical error present in the lidar-derived elevation data. Differences in mean vertical elevation error between the low-and high-altitude lidar data collection missions were primarily due to a systematic underestimation bias present in the high-altitude lidar data.