Category: Foundations
Remote Sensing
Remote sensing measures Earth from a distance using sensors that record reflected or emitted energy.
Also known as: satellite sensing, aerial sensing
Expanded definition
Remote sensing is the umbrella term for observing objects without direct contact. In Earth observation, sensors typically measure reflected sunlight (optical), thermal emission (thermal infrared), or returned radar signals (SAR).
Remote sensing data is indirect. Pixel values must be interpreted with context such as illumination, atmosphere, sensor geometry, and land cover. Because of that, good remote sensing products document what is measured (radiance, reflectance, backscatter), at what resolution, and what corrections were applied.
Remote sensing is powerful because it scales. One consistent method can cover large areas repeatedly, which is hard to do with field measurements alone.
Related terms
Earth Observation (EO)
Earth observation is the use of satellites, aircraft, or drones to measure and monitor the planet’s surface and atmosphere.
Optical Imagery
Optical imagery measures reflected sunlight, providing rich spectral information but being sensitive to clouds and illumination.
SAR (Synthetic Aperture Radar)
SAR is an active radar sensor that works day or night and can see through clouds, measuring surface scattering rather than reflected sunlight.