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OkMap – User manual
December 14, 2015
Logical expression
consists of logical operators, operands and pairs of brackets, organized according to syntactic
rules specified, so as to express a group of operations that provide a single result. It is used
to make selections between classes of elements in the process of data analysis.
Logical operator
entities used to formulate, for instance in a database, the logical conditions for the selection
of records in according with the values of the fields. See SQL.
Longitude
see geographical projection.
M
Mass memory
device that allows the permanent storage of data (generally the hard drive of the computer).
MB (Megabyte)
unit of information in memory, equal to one million bytes (characters).
Metadata
are information about the data sets in a database. A set of metadata can be considered
consistent when, in the way most synthetic possible, provides an adequate description of the
content, quality and characteristics of the data.
Metric precision
is a quality parameter of a local mapping defined as the difference in position of a point on
the map compared to its real position in the national cartographic reference system.
Mosaicing
is the set of operations that, within the GIS, allows you to merge multiple maps in digital
format to create a territorial continuity.
N
Nadir
the vertical drawn from any point within the earth's surface, where is the observer, meets
the celestial sphere in two opposite points. Nadir is what lies below the horizon, the other,
which is above, is the zenith.
Native format
source format in which an object (program, file, data) was originally written.
Node
is a point with topological characteristics describing the beginning or end of an arc.
Nominal scale
is a parameter that defines the scale of reference for a digital mapping according to the
corresponding scale of a traditional cartography realized following the same requirements of
metric accuracy.
NTF (National Transfer Format)
data format used for interchange of data between topological GIS (adopted by the Italian
Inventory).
O
Object
physical or logical entity defined by a set of characteristics and rules of behavior which
express the state of static or dynamic. For example in a GIS object could be the set of a
telephone plant, its connections and its related management procedures.
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