Is UAV-SfM surveying ready to replace traditional surveying techniques?

The creation of high-resolution Digital Elevation Models (DEMs) through the acquisition of images with a consumer-grade camera mounted on a light Unmanned Aerial Vehicle (UAV) and their processing with Structure from Motion (SfM) software has been widely adopted in different fields. Despite this wide adoption, its use has been limited to research projects - as in our experience most practising surveyors, think that the topography obtained through this technology is subpar to that obtained with surveys undertaken with traditional methods. To address this concern, we compare these two approaches in a heterogeneous built-up area of nearly 33 ha with an elevation between 1899 and 1944 m a.s.l. This comparison shows that the UAV-SfM methodology provides better results than the traditional method, is less prone to human error and also requires significantly less time: 4 h of fieldwork instead of 1 week. Furthermore, the spatial resolution of a Total Station (TS) survey is only limited to those points surveyed, whereas the UAV-SfM derived topography is a subproduct of the resultant three dimensional point cloud, which can also be used to generate a high-resolution orthophoto.