Why are there more/less ground class points in a given area?
Many factors influence the density of ground points in an area. Dense vegetation, aerosols, buildings, and smoke prevent lidar pulses from reaching the ground. Dark surfaces such as fresh asphalt reflect poorly and may prevent returns to the sensor. The variable reflectivity and refractivity of standing water often results in unreliable returns. Conversely, areas may have better than average point density due to decreases in plane speed and/or overlap between flight lines. Overall, PAMAP lidar data is designed to provide an average point spacing of 1.4 meters.
