Remote sensing, i.e. the process of obtaining information about an object or area from a distance, is not possible without remote sensing sensors that collect this information and the platforms on which the sensors are installed and which are used to move them. Remote sensing sensors collect data by detecting energy that is reflected or emitted from Earth. There are different types of remote sensing sensors. The interaction between the sensor and the Earth's surface has two modes: active or passive. Passive sensors use solar radiation to illuminate the Earth's surface and detect reflection from the surface or measure the emitted energy. They usually record electromagnetic waves in the visible (˜430–720 nm) and near infrared (NIR) (˜750–950 nm) through short infrared (SWIR) (˜1.500-2.500 nm) to thermal infrared (TIR) (8.000-14.000 nm) ranges. The power measured by passive sensors is a function of surface composition, physical temperature, surface roughness and other physical properties of the Earth. Active sensors provide their own energy source to illuminate objects and measure their properties. These sensors use electromagnetic waves in the visible and near infrared range (e.g.laser altimeter) and radar waves (e.g. synthetic aperture radar (SAR)). As sensor technology has advanced, the integration of passive and active sensors into one system has emerged. Alternatively, remote sensing sensors can be classified into imaging sensors, i.e. that produce an image of an area, within which smaller parts of the sensor's whole view are resolved (pixels), and non-imaging sensors, i.e. that return a signal based on the intensity of the whole field of view. In terms of their spectral characteristics, the imaging sensors include optical imaging sensors, thermal imaging sensors, and radar imaging sensors. These sensors can be on satellites, mounted on aircraft, unmanned aerial vehicle (UAV), drone or ground. The collected information can be transformed into an image or set of points (e.g. cloud points), which can be further processed and analyzed to obtain the necessary information, e.g. agricultural field development phase, level of air pollution, etc. A digital imagery of Earth observation sensors is a two-dimensional representation of objects on Earth. Current images collected from different levels of acquisition, from ground to satellite, with the help of electronic sensors are examples of digital images. There are different aspects and characteristics of remote sensing data and images, such as, for example, data formats and processing levels, data storage, data properties.
Discuss the main types of remote sensing sensors
Discuss the main types of remote sensing platforms
Discuss the main types of remote sensing data
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