Terms starting with L

LABEL

(window context) The static text part of a component that presents information to the user about that component, such as the action invoked by a push button or the mode selected by a check button.

LABELING

(raster context) Identifying and grouping the clusters that result from any kind of automated image interpretation. You choose labels (names for types of features) based upon your knowledge of the areas or materials in the image.

LAND COVER

The materials that cover a study site, such as vegetation, bare soil, rock, sand, and water.

LAND USE CLASSIFICATION SYSTEM

Coding system of categories and subcategories designed for use on a map to designate land or water use.

LANDMARK

Monument of material mark or fixed object used to designate a land boundary on the ground: any prominent object on land that may be used to determine a location or a direction in navigation or surveying.

LANDSAT SATELLITE

A satellite that collects multispectral images. At various times it uses 1) a Return Beam Vidicon (RBV) device, 2) the Multispectral Scanning (MSS) device, and 3) the Thematic Mapping (TM) scanning device. Landsat also relays data from ground observation stations. Landsat was originally called the ERTS or Earth Resource Technology Satellite.

LATITUDE/LONGITUDE

Latitude is the angular distance, measured in degrees, north or south from the equator. Longitude is the distance east or west on the Earth's surface measured as an arc of the equator (up to 180 degrees) between the meridian passing through a particular place and the prime meridian, passing through Greenwich, England. Look up the data availability in your area of interest by providing a Lat/Long on the web "Search Archive" or learn what Lat/Long covers your area of interest. This will assist fulfillment when ordering.

LEAD LINE

Line weighted with lead for making depth soundings in water.

LEVEE

Artificial bank confining a stream channel or limiting adjacent areas subject to flooding; an embankment bordering a submarine canyon or channel, usually occurring along the outer edge of a curve.

LEVEL SURFACE

Surface which at every point is perpendicular to the plumbline or the direction in which gravity acts.

LEVELING

Surveying operation in which heights of objects and points are determined relative to a specified datum.

LICENSES

Data is sold with an End User License that indicates permitted uses and prohibited uses. For more information about the different licenses available, refer to Licensing in the Warranty & Licensing Section.

LINE COPY (LINE DRAWING)

Map copy suitable for reproduction without the use of a screen; a drawing composed of lines as distinguished from continuous- tone copy.

LOW WATER

Minimum height reached by a falling tide. The height may be due solely to the periodic tidal forces or it may have superimposed upon it the effects of meteorological conditions. 

Low Water Line: Intersection of the land with the water surface at an elevation of low water. Not to be confused with mean low water line.