ABSTRACT
One of the earliest dreams of humans has been to observe Earth and its landscapes from a bird’s perspective. This was only possible with the advent of balloons, gliders, and airplanes. A key driving force in our quest to fly above the ground has been to find new perspectives from which to observe Earth’s diverse landscapes. Our view of Earth is quite limited when we are confined to the ground. Our desire to survey entire landscapes, mountain ranges, volcanoes, hurricanes, rivers, and ice fields has been evident since the beginning of aeronautics and now forms the foundation of space-based Earth observation (EO). Today, as a result of rapid technological advances, we routinely survey our planet’s surface from different platforms: lowaltitude unmanned aerial vehicles (UAVs), airplanes, and satellites. The surveillance of Earth’s terrestrial landscapes, oceans, and ice sheets constitutes the main goal of remote sensing techniques. The term “remote sensing” was first utilized in the early 1960s to describe any means of observing the Earth from afar, particularly as applied to aerial photography, the main sensor used at that time. In a broader context, remote sensing activities include a wide range of aspects, from the physical basis to obtain information from a distance, to the operation of platforms carrying out the sensor system, to the data acquisition, storage, and interpretation. Finally, the remotely collected data are converted to relevant information, which is provided to a vast variety of potential end users: farmers, foresters, fishers, journalists, glaciologists, ecologists, geographers, etc. Nowadays, satellite images have become widely accessible by ordinary people, who use them within well-known images or map services, as basis for planning tourist routes or finding shops and services.
