Derivation of sky-view factors from lidar data

The use of lidar (light detection and ranging), an active light-emitting instrument, is becoming increasingly common for a range of potential applications. Its ability to provide fine-resolution spatial and vertical-resolution elevation data makes it ideal for a wide range of studies. This article demonstrates the ability of lidar data to measure sky-view factors (psi(s)). The lidar data are used to generate a spatial map of psi(s), which are then compared against photographically derived psi(s) at selected locations. At each location, three near-surface elevation measurements were taken and compared with collocated lidar-derived estimates. Generally a good agreement was found between the two methodologies, although with decreasing psi(s), the lidar technique tended to overestimate psi(s). This can be attributed in part to the spatial resolution of the lidar sampling. Nevertheless, airborne lidar systems can easily map psi(s) over a large area, potentially improving the use of such data in atmospheric and meteorological models.