Drones map snow depth

This is new (to me): Harder et al. (2016) used a senseFly eBee RTK UAV to map snow depth. In essence you fly first over snow-free terrain and create a DSM, then create a second DSM over snow cover and subtract the two - clever. There are some limitations (e.g. snow depth has to be greater than 30 cm), but otherwise this seems quite feasible.