Landsat
A series of unnamed earth-orbiting NASA satellites that acquire multispectral images in various
visible and IR bands.

Laplacian filter
A form of nondirectional digital filter.

Laser
Light artificially stimulated electromagnetic radiation: a beam of coherent radiation with a single wavelength.

Latent image
Invisible image produced by the photochemical effect of light on silver halide grains in the emulsion of film.
The latent image is not visible until after photographic development.

Layover
In radar images, the geometric displacement of the top of objects toward the near range
relative to their base.

L band
Radar wavelength region from 15 to 30 cm.

Lens
One or more pieces of glass or other transparent material shaped to form an image by refraction of light.

LFC
Large-format camera.

Lidar
Light intensity detection and ranging, which uses lasers to stimulate fluorescence in various compounds
and to measure distances to reflecting surfaces.

Light
Electromagnetic radiation ranging from 0.4 to 0.7µm in wavelength that is detectable by the human eye.

Light meter
Device for measuring the intensity of visible radiation and determining the appropriate exposure of photographic film in a camera.

Lineament
Linear topographic or tonal feature on the terrain and on images, maps, and photographs that may
represent a zone of structural weakness.

Linear
Adjective that describes the straight line-like nature of features on the terrain or on images and photographs.

Lineation
The one-dimensional alignment of internal components of a rock that cannot be depicted as an individual feature on a map.

Line drop out
The loss of data from a scan line caused by malfunction of one of the detectors in a line scanner.

Line-pair
Pair of light and dark bars of equal widths. The number of such line-pairs aligned side by side that can be distinguished per unit distance expresses the resolving power of an imaging system.

Line scanner
An imaging device which uses a mirror to sweep the ground surface normal to the flight path of the platform. An image is built up as a strip comprising lines of data.

Look angle
The angle between the vertical plane containing a radar antenna and the direction of radar propagation. Complementary to the depression angle.

Look direction
Direction in which pulses of microwave energy are transmitted by a radar system. The look direction is normal to the azimuth direction. Also called range direction.

Look-up table (LUT)
A mathematical formula used to convert one distribution of data to another, most conveniently
remembered as a conversion graph.

Luminance
Quantitative measure of the intensity of light from a source.