Geodesy and Geoinformation: What's that?
After the invention of color photography is was soon obvious that beside geometric information also qualitative information about the pictured objecte can be extracted from the photos: for instance by interpretation of colors brown and green it can be concluded, if agricultural used zones are fields or meadows. While the color film works with three different spectral ranges (red/green/blue), present-day sensors of remote sensing utilize a multitude of different spectral ranges even outside the visible light: many matching images in different spectra are recorded, which can be combined almost arbitrarily to deduce various qualitative information about objects. By integration of with image geometry those information can be correctly located, e.g. in maps or information systems.
Classical tasks of remote sensing are object classification and inventory, e.g. for the determination of type and status of agricultural and forestal land use.
Today remote sensing includes also the processing of imaging sensors of all kind which are onboard of satellites (spaceborne remote sensing). Examples are weather satellites and environment monitoring systems for detection of ocean pollution, desertification, forest fires and others.
Part of remote sensing are also systems to observe ground motions: with the radar altimetry satellite images from different times (e.g. different years) land subsidence can be monitored and verified laminary, e.g. in mining areas. Furtheron remote sensing images can be exploited for the determination of terrain models for a variety of applications with sufficient acuracy..
All above mentioned applications are deployed not only for Earth monitoring but also in space missions to planets and other celestial bodies.