Glossary

The amount of light directly detected by remote sensing instruments. 

 A device that detects and measures electromagnetic radiation.

Relating to, using, or measured by a radiometer. The measurement of radiation.

An abstraction of the real world where spatial data is expressed as a matrix of cells or pixels, with spatial position implicit in the ordering of the pixels. With the raster data model, spatial data is not continuous but divided into discrete units. This makes raster data particularly suitable for certain types of spatial operations (e.g. overlays or area calculations). Unlike vector data, there are no implicit topological relationships.

Numerical values representing the direct observations output by a measuring instrument. The values are transmitted as a bit stream in the order they were obtained.

The time in which reporting on events or recording of events is simultaneous with the events. For example, the real time of a satellite is the time in which it simultaneously reports its environment as it encounters it.

The measure of the proportion of light or other radiation striking a surface which is reflected off it.

The relative azimuth angle between the sun and view directions. 

The relative azimuth angle between the incident and exiting directions in the slope geometry. 

The measurement or acquisition of information about some property of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object or phenomenon under study.

Remote sensing instruments record characteristics of objects at a distance, sometimes forming an image by gathering, focusing and recording reflected light from the sun, or reflected radio waves emitted by the spacecraft.