Edge enhancement: The use of image filtering techniques to emphasise
changes in data values in imagery.
Electromagnetic radiation (EMR): Energy propagated through space
or through material media in the form of an advancing interaction between
electric and magnetic fields. The term radiation, alone, is commonly used
for this type of energy, although it actually has a broader meaning; also
called electromagnetic energy.
Electromagnetic spectrum: The ordered array known as electromagnetic
radiation extending from the shortest cosmic rays, through gamma rays, X-rays,
ultraviolet radiation, visible radiation, infrared radiation, and including
microwave and all other wavelengths of radio energy.
Element: The structural unit along the X-axis of a digital range.
This unit is usually referred to as the 'pixel' position.
Elevation: (1) Vertical distance from the datum, usually mean sea
level, to a point or object on the Earth's surface. Not to be confused with
altitude, which refers to points or objects above the Earth's surface. (2)
architectural: An orthographic projection of any object into a vertical
plane.
EM spectrum: Electromagnetic spectrum.
Emissivity (e): The ratio of radiant exitance (M) of a surface to
the radiant exitance of a blackbody at the same temperature. A blackbody
has an emissivity of 1, other objects have emissivities between 0 and 1.
Emittance: The obsolete term for the radiant flux per unit area emitted
by a body, or exitance.
EMR: Electromagnetic radiation.
Energy (Q): Over a range of wavelengths, this is defined as the number
of photons times the energy per photon, monochromatically.
Enhancement: Data filtering and other processes that improve the
visual quality of the pictorially presented data or that visually accentuate
a characteristic of the data.
Environmental satellites: Satellites imaging large areas for environmental
monitoring, such as NOAA AVHRR.
EOS: Earth Observing System.
EOSAT: Earth Observation SATellite company; commercial operator of
Landsat satellite data since September 1985.
Ephemeral data: Data that (1) help to characterise the conditions
under which the remote sensing data were collected; (2) may be used to calibrate
the sensor data prior to analysis; (3) include such information as the positioning
and spectral stability of sensors, sun angle, platform attitude, etc.
ERTS: Earth Resources Technology Satellite; later renamed to Landsat
1.
ESA: European Space Agency.
ESRI: Environmental Systems Research Institute; company responsible
for developing and marketing ARC/INFO.