Remote Sensing (RS) is a type of geospatial technology that collects samples of emitted and reflected electromagnetic (EM) radiation from terrestrial, atmospheric, and aquatic ecosystems to detect and monitor the physical characteristics of the terrain without physical contact. This method of data collection typically involves aerial (currently exclusively UAVs) and satellite sensors, which are classified as passive or active sensors. Ground sensors (instruments) are used at the local level and to enhance the quality of satellite and aerial data.
In recent years, ground RS sensors have been included in the field of remote sensing, which, in combination with space and aviation as carriers of sensors, allows for a new level of detail in the studied area or object.
Passive sensors respond to external stimuli by collecting radiation that is reflected or emitted by an object or the surrounding space. The most common source of radiation measured by passive remote sensing is reflected sunlight. Popular examples of passive remote sensors include charge-coupled devices, digital photography and video recording, radiometers, hyperspectral, and infrared sensors.