Chapter 4 Flashcards
Central Meridian
The central longitude of a map projection for which the X coordinate equals zero.
Coordinate Pair
A single pair of x and y values indicating position in a planar coordinate system. A single pair indicates a point, a series indicates a line.
Coordinate Space
The range of x and y values onto which maps are plotted; an agreed upon range of coordinates used to portray the features.
Coordinate System
(1) A specified rage of x-y values onto which a map is potted.
(2) The definition of a coordinate space used by a map layer including the ellipsoid, datum, and projection.
Datum
A combination of an earth ellipsoid and a reference point to reduce mapping discrepancies.
Define Projection Tool
A tool to guide the user through the task of assigning a coordinate system to a spatial data layer.
Degrees
The measurement units used in the spherical coordinate system; a circle has 360 degrees.
Display
The units in which the current x-y location of the cursor on the map is reported.
Extent
The range of x-y coordinates occupied by the features in a data layer.
False Northing
An arbitrary y-coordinate translation applied to a map projection, usually to ensure that all values are positive.
Geoid
The shape of the earth as defined by sea level and affected by topographic and gravitational forces.
Latitude
A spherical unit measuring angular distance north or south from the equator (x axis, stretching east/west)
Latitude of Origin
The reference latitude of a map projection where the y value equals zero.
Longitude
A spherical unit measuring angular distance east or west from the prime meridian (y axis, stretching north/south)
Map Units
Units of the coordinate system in which a map is stored or displayed (meters, feet, etc)
