label
(CAD context) A CAD element that contains text used to identify a point, line or polygon element.
label
(vector context) Text in a vector object used to identify a point, line, or polygon element.
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.
LAI
See - leaf area index.
land cover
The materials that cover a study site, such as vegetation, bare soil, rock, sand, and water.
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.
LAS
A raster-based, public domain image processing system.
lateral connections
HyperIndex connections between objects on the same hierarchical level. The connections may be individually established by the user or automatically estimated. HyperIndex displays a list of laterally connected objects when a user indicates a move in that direction with the arrow key.
Latin alphabet
The character encoding scheme used by most Western nations, based on the alphabet developed in Roman antiquity, itself a derivative of the Greek and Western Semitic alphabets. The Latin alphabet is used by the languages of Western Europe, including English, as well as many other languages such as Turkish, Swahili, and Vietnamese. The Latin alphabet is sometimes referred to as the Roman alphabet, but "Roman" is not used in this discussion so as to avoid confusion, since the term "Roman" is often used in typeface and character style contexts.
Latin-1
(also known as ISO 8859-1) A super set of the 7-bit ASCII character encoding scheme that includes various symbols plus letters with diacritics commonly used in European languages. Latin-1 is an 8-bit character encoding scheme, containing 256 characters. Latin-1 makes different assignments for codes 128-255 than does PC-8. Latin-1 is, however, consistent with the Unicode and ISO 10646 standards, and is the common encoding scheme used by Unix systems.
latitude
The angular distance in degrees of a point on the earth north or south of the equator.
Lattice
A surface representation that uses a rectangular array of mesh points spaced at a constant sampling interval in the X and Y directons relative to common origin, A lattice is stored as a grid, but represents the value of the surface only at the mesh points rather then the value of the centre cell.
layer
A display entity comprised of one or more components that can be manipulated separately from other layers. There is often a one-to-one correspondence between layers and objects, but an individual layer may be comprised of multiple objects, such as the red, green, and blue components used to create a single layer in multiple raster display.
leaf area index or LAI
A unit-less, biological measure equal to the ratio of the one-sided surface area of the leaves in an in situ crop, forest, or grassland canopy to the ground area.
least squares
A mathematical method for fitting a line or curve to a set of data points. Least squares minimizes the sum of the squares of the error term at each point.
Lengend
1. The reference area on a map that lists and explains the colors, symbols, line patterns, shadings and annotation used on the map. The legend often includes the scale, origin, orientation and other map information.
2. The symbol key used to interpret a map.
level
In HyperIndex, any object or file that is displayed in the Display / Spatial Data window is called a level. A level may originate from a raster, vector, or CAD object. However, in HyperIndex, the level assumes an identity beyond that of the object or file itself, because the level includes the index areas that have been defined and any links to other objects. Thus, in addition to being an image, a level lets you access many different kinds of information. (See also: HyperIndex, index area, link, stack.)
limit line
An adjustable graphic line on a process control screen that defines the boundary between values that are used and values that are not used in the process.
line
(raster) One horizontal row of cells (or pixels) in a raster object (or display image).
linear contrast
See - contrast.
Linear feature
A geographic feature that can be represented by a line or set of lines. For example, rivers, roads within a pizza delivery area, and electric and telecommunication networks are all linear feature.
linear transform
(map registration) One kind of map registration subobject (Regist) that contains an object's mathematical representation for its calibration solution (least squares) derived from a control point list.
line element
One of the types of elements which make up a vector object. A line is defined by an ordered string of coordinates which define a curved path in space. Line attributes include-
| attribute |
example |
| ID number |
a unique reference number |
class |
intermittent stream |
|
group number | hydrology |
|
color | RGB line color |
|
database record no. | pointer to record |
|
line pattern | slashes on line |
|
line width | thickness |
Vector element class attributes may be cross-indexed to a list containing the database record, polygon fill pattern, line drawing pattern, point symbol, line width or symbol/point size, RGB color, RGB label color, RGB fill color, label font number, label font size, label font zoom factor, label font style, and label rotation angle.
Line-in-polygonA spatial operation in which arcs in one coverage are overlaid with polygons in another to determine which arcs, or portions of arcs, are contained within the polygon attributes are associated with the corresponding arcs in the resulting line coverage.
line pattern
The drawing style of a line for display or printing
link
(to external database or raster object). A project file link to an external database file contains the file name, device location, and field/record information about the database file.
link
(HyperIndex). The relational connection between a region (or index area) on a parent object and daughter object in a HyperIndex stack
list box
A scrollable list of options from which to choose.
local variable
(SML) Variables that belong to a function or procedure and exist only for that procedure are "local variables." No variable is local unless it has been explicitly designated so with the "local" statement in the function or procedure. A local variable may have the same name as a variable used elsewhere in the program without affecting it.
locale
One collection of data that defines the semantics for a specific language and set of cultural conventions. Standard C provides a Locale structure which includes six aspects of the local culture and language: 1) Collation / sort sequence for characters, 2) Character type, 3) Money and currency symbols and formats, 4) Numerical formats: a point or comma for decimal demarcation, 5) Time - names of the weekdays, 6) Messages - yes/no, program status and prompts.
localization
Providing the run-time data that describes the necessary elements of a locale for an internationalized program so it can use the correct character encoding scheme, font, keyboard conventions, collation sequence for the alphabet, and so on.
Logical Connector
One of the reserved words AND, OR and XOR used to build complex logical expression in query.
Logical operatorAnother term for Boolean operator.
Log file
A coverage or workspace history file containing a list of all commands used to operate on a coverage or all commands used in the work space.
Logical expressionA combination of items, system items, system variables, literals and arithmetic logical operators from which a value of TRUE or FALSE is derived; for eg.
$RECNO LE$NUMI HRS - WORK * HRLY- WAGE GE 600 AND $ MONTHEQ 5 $NOMILE 100
longitude
The angular distance in degrees of a point on the earth east or west of the Prime Meridian.
low-pass filter
A process that smoothes or reduces the spatial variability or detail in a continuously varying raster object. (See also: filtering)