We discuss the evolution and state-

We discuss the evolution and state-of-the-art of the use of Unmanned Aerial Systems (UAS) in the field ofPhotogrammetry and Remote Sensing (PaRS). UAS, Remotely-Piloted Aerial Systems, Unmanned AerialVehicles or simply, drones are a hot topic comprising a diverse array of aspects including technology, privacy rights, safety and regulations, and even war and peace. Modern photogrammetry and remote sensing identified the potential of UAS-sourced imagery more than thirty years ago. In the last five years,these two sister disciplines have developed technology and methods that challenge the current aeronautical regulatory framework and their own traditional acquisition and processing methods. Navety andingenuity have combined off-the-shelf, low-cost equipment with sophisticated computer vision, roboticsand geomatic engineering. The results are cm-level resolution and accuracy products that can be generated even with cameras costing a few-hundred euros. In this review article, following a brief historicbackground and regulatory status analysis, we review the recent unmanned aircraft, sensing, navigation,orientation and general data processing developments for UAS photogrammetry and remote sensing withemphasis on the nano-micro-mini UAS segment