*2.1. Definitions-Brief Description of Current and Future Capacities*

"Remote sensing may be broadly defined as the collection of information about an object without being in physical contact with the object. Aircraft and satellites are the common platforms from which remote sensing observations are made. The term remote sensing is restricted to methods that employ electromagnetic energy as the means of detecting and measuring target characteristics" (Sabins 1978). Remote sensing systems are based on signals and images acquired by sensors installed on artificial satellites or aircraft and are used for vast geographical phenomena (di Vimercati et al. 2013). The advancement of satellite technologies and unmanned aerial vehicles has been remarkable last decades. The technological development of satellite technologies on one hand has led to on-demand satellite constellations, which deliver high resolution data (0.75 m) with a daily revisit interval anywhere around the globe. In addition to the high resolution, they can acquire a sequence of images with a small time interval (video persistent mode) due to their unique rapid sensor depointing agility (Almar et al. 2019). Furthermore, as more countries gain their own Earth observation capability, commercialization is a common theme (Harris and Baumann 2021). On the other hand, unmanned aerial vehicles or "drones", although initially used almost exclusively for military applications, it is now to mention their rapid development for civil applications, and it has even been said that "we are entering the drone age" (Anderson 2012). The surveillance capabilities of drones are rapidly advancing and cheap storage is now available<sup>3</sup> . The capabilities of drones depend on what they are able to carry. Due to the growing commercialization of drones, commercial UAV manufacturers will increasingly improve their products following the needs of their clients. Additionally, a service sector will evolve to offer UAV services such as leased systems, on-demand flights, or consultation for choosing appropriate platforms or analyzing UAV-generated data (Watts et al. 2012).

To sum up, the future of remote sensing technologies can be described into three words: development, privatization, commercialization.

<sup>3</sup> Drones and Environmental Monitoring. 2017. Environmental Law Institute, Washington, DC, USA.
