Human perception is limited, and we can't see very far and catch light that is too tiny and faint. What's more, the range of spectral beyond the visible spectrum is imperceptible to us. And the height of space is a limitation for most people who cannot observe the earth. However, fortunately, we have a magical technology, remote sensing, which expands our perception capabilities and breaks through our limitations through advanced sensors and instruments.
Academician Tong Qingxi once said: The essence of remote sensing is the extension of human vision in the two dimensions of distance and spectrum. This technology extends our vision over distances of hundreds of kilometers, even tens of thousands of kilometers, through satellite remote sensing sensors, while spectrally extending our perception from the narrow spectrum of visible light to the electromagnetic spectrum of microns to meters.
In China, more than 40 civil land observation satellites have been launched, and these satellites carry hundreds of remote sensing sensors, providing us with a wealth of surface information. The characteristics of these sensors are as follows:
Diverse sensor types: including multispectral, hyperspectral, infrared, synthetic aperture radar, lidar, etc., basically covering the entire electromagnetic imaging spectrum.
Diverse detection methods: Different special sensors can receive signals such as intensity, phase, polarization, and polarization of electromagnetic waves emitted or reflected by ground objects, and also include multi-angle imaging to detect the surface in all directions.
Multi-spatial scale: The spatial resolution ranges from sub-meter to kilometer, and the width of the imaging covers from 10 kilometers to thousands of kilometers.
Single-satellite multi-sensor integrated observation: A satellite can carry multiple sensors and comprehensively observe the surface at the same time, covering a variety of wavelength ranges, multiple angles, active and passive detection methods, etc.
Through these remote sensing technologies, we are able to see and understand the Earth in depths like never before. This not only provides a wealth of data for scientific research, but also brings revolutionary changes in the fields of resource management and environmental monitoring. The wonderful use of remote sensing technology is pushing our vision to new frontiers, bringing the miracle of observing the world to mankind.