A
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address |
A physical location that can be used as the unique identification for a location.
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aerial photography |
A photograph, usually taken from an airplane, to record ground level events. Not to be
confused with satellite remote sensing which produces digital images, aerial photography
provides black and white, color and infrared photographs on film.
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arc |
An term that is used synonymously with line.
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B
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basemap |
The basic features and layers that will be included on every map request made or printed.
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buffer |
The specific distance around the location you are focused on.
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C
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CAD |
Computer-aided design. A computer-based system for the design, drafting, and
display of graphical information. Also known as computer-aided drafting, such
systems are most commonly used to support engineering, planning and illustrating
activities.
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cartography |
The art and science of expressing graphically, usually through
maps, the natural and social features of the earth.
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census block |
The smallest geographic entity for which the U.S. Bureau of
the Census tabulates decennial census data. Visible and/or invisible features shown on a
map prepared by the U.S. Census Bureau bound its geographic area. Many blocks correspond
to city blocks bounded by streets, but blocks in rural areas may include many square miles
and have some boundaries that are not streets. The Census Bureau established blocks covering
the entire nation for the first time in 1990. Previous censuses back to 1940 had blocks
established only for part of the nation.
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census geography |
The collection of various types of geographic areas used by the U.S. Bureau of the
Census in its data collection and tabulation operations, including their structure,
designations and relationships to one another. The largest unit of area is the entire
United States, while the smallest is a census block.
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census tract |
A small, relatively permanent statistical subdivision of a county. Tract boundaries
normally follow visible features, but may follow governmental unit boundaries or other
non-visible features. Designed to be relatively homogeneous units with respect to
population characteristics, economic status and living conditions at the time of
establishment, census tracts average about 4,000 inhabitants.
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centerline |
A line digitized along the center of a linear geographic feature, such as a street or a river, that at a large enough scale would be represented by a polygon. |
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center map |
A map tool that recenters the current map based on a selected
point.
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centroid |
The geometric center of a feature. Of a line, it is the midpoint; of a polygon, the
center of area; of a three-dimensional figure, the center of volume.
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city view |
A view in which the entire city of Phoenix and outlying suburbs is displayed.
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compass rose |
A small compass drawn on a map or chart, subdivided clockwise from 0 to 360 degrees with 0 indicating true north. On older maps and charts it was a decorated diagram of cardinal directions, divided into sixteen or thirty-two points. Originally called rosa ventorum, or "rose of the winds," it is sometimes still referred to as a wind rose. |
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coordinate |
Coordinates generally represent locations on the earth's surface relative to other
locations utilizing an X (horizontal) and Y (vertical) axis.
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D
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datum |
In the most general sense, any set of numeric or geometric constants from which other
quantities, such as coordinate systems, can be defined. A datum defines a reference
surface. There are many types of datums, but most fall into two categories: horizontal
and vertical.
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diameter |
A straight line segment passing through the center
of a figure. The diameter of a circle is twice the distance of the circle's radius. |
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digital elevation model (DEM) |
The representation of continuous elevation values over a topographic surface by a regular array of z-values, referenced to a common datum. Typically used to represent terrain relief. |
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dimension |
A measurement in one direction. Specifically, one of three coordinates determining a position in space, or four coordinates determining a position in space and time. |
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dragging |
Relocating display elements on a computer screen with a pointing device, such as a mouse. This can be done by pressing and holding a button (on the mouse) while moving the pointer on the screen. |
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E
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edgematching |
A spatial adjustment process that aligns features along the edge of one layer to features of an adjoining layer. The layer with the least accurate features is adjusted, and the adjoining layer is used as the control. |
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F
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Federal Geographic Data Committee (FGDC) |
An organization established by the
U.S. Federal Office of Management and Budget responsible for
coordinating the development, use, sharing and dissemination of surveying,
mapping and related spatial data. The committee is comprised of
representatives from federal and state government agencies, academia
and the private sector. The FGDC defines spatial data metadata standards
for the United States in its Content Standard for Digital Geospatial
Metadata and manages the development of the National Spatial Data
Infrastructure (NSDI). |
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feature |
A set of points, lines or polygons in a spatial database that represent a real-world 'thing'. The terms feature and object are often used synonymously. |
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G
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geocoding |
The process of finding the location
of a street address on a map. The location can be an x,y coordinate or a
feature such as a street segment, postal delivery location or building. In
GIS, geocoding requires a reference dataset that contains address attributes
for the geographic features in the area of interest. |
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GIS |
A computer system for capturing,
storing, checking, integrating, manipulating, analyz
related to positions on the Earth's surface. Typically, a Geographical
Information System (or Spatial Information System) is used for handling
maps of one kind or another. These might be represented as several different
layers where each layer holds data about a particular kind of feature. Each
feature is linked to a position on the graphical image of a map. |
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H
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I
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identify |
A map tool that allows you to click on a feature of the map and access any information about that feature that is contained in our databases. |
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J
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K
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L
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land information system (LIS) |
A commonly used term refering to a system for capturing, storing, checking, integrating,
manipulating, analysing and displaying data about land and its use, ownership and
development.
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latitude |
The angular distance, usually measured in degrees, along a meridian north or south of
the equator. Lines of latitude are also referred to as parallels.
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layer |
Different types of geographic data are called "layers." Any number of layers
may be viewed at one time, depending on the zoom level in the current map view. The order
in which layers are displayed on a map is critical to visual presentation. For instance,
if two polygon shapes overlap each other special care must be taken to make them both
visible. This can be accomplished by making the uppermost layer "transparent"
so that the color of the underlying layer can also be seen. Another method is to display
the uppermost layer with "hash" lines, or a pattern of some kind so it
is easily distinguished.
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legend |
The reference area on a map that lists and explains the colours, symbols, line patterns,
shadings, and annotation used on the map. The legend often includes the scale, origin,
orientation, and other map information.
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line |
A set of ordered coordinates that represent the shape of geographic features too
narrow to be displayed as an area at the given scale (contours, street centerlines
or streams), or linear features with no area (county boundary lines). A lines is
synonymous with an arc.
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longitude |
The angular distance, expressed in degrees, minutes and seconds, of a point on the
earth's surface east or west of an arbitrarily defined meridian (usually the Greenwich
prime meridian). All lines of longitude are great circles that intersect the equator
and pass through the north and south poles.
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M
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map |
A graphic representation of features of the earth's surface or other geographically
distributed phenomena. Examples are topographic maps, road maps, weather maps.
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map category (or map theme) |
A grouping of map features based on a specific topic. The following lists are a representative
sample and do not reflect a complete list of the features for each category.
Recreation and Points of Interest: Includes city-owned or public parks,
mountain preserves, desert parks, sports complexes, swimming pools, golf courses, bikeways,
light rail corridor, libraries and points of pride.
School Information: Includes district, charter and private school information
such as individual school locations, and district and attendance boundaries.
Neighborhoods: Includes congressional and state legislative districts, parks,
mountain preserves, desert parks, historic districts, Fight Back areas, neighborhood
associations, redevelopment areas, family services and senior centers, libraries, fire and
police stations.
Planning and Zoning: Includes information about the physical development of the
city such as the general plan, annexations, light rail corridor, zoning overlays, regulatory plan
areas and zoning.
Transportation: Includes streets, freeways, bikeways and bike bridges as well as
the location of speed humps and the type of traffic signals on many intersections.
General Statewide Information: Includes counties, incorporated and unincorporated
cities and county seats. Most of the statewide information has been provided
to the city by the Administration and Resource Analysis Division of the
Administration and Resource Analysis
Division of the Arizona State Land Department.
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map unit |
The ground units of measurement-for example, feet, miles, meters or kilometers - in which
the coordinates of spatial data are stored.
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meridian |
A great circle on the earth that passes through the poles, often used synonymously with
longitude. Meridians run north-south between the poles. From a prime meridian or 0 degrees
longitude (usually the Greenwich prime meridian), measures of longitude are negative to
the west and positive to the east, where they meet halfway around the globe at the line
of 180 degrees longitude.
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N
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NAD83 |
North American Datum of 1983. A geocentric datum and graphic coordinate system based on
the Geodetic Reference System 1980 ellipsoid (GRS80). Mainly used in North America, its
measurements are obtained from both terrestrial and satellite data. Replaces the NAD27
coordinate system.
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O
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orthophotograph |
A perspective aerial photograph from which distortions owing to camera tilt and ground
relief have been removed. An orthophotograph has the same scale throughout and can be
used as a map.
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P
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pan |
A map tool that allows you to click and drag the map in any direction. To pan the map,
move the cursor over the map, hold down the mouse button, and drag the map in any
direction. Release the mouse button to leave the map in your desired position. The
application will update the map display to fill in any blank areas revealed by your pan.
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parcel |
A tract or plot of land. The term is usually used in the context of land use or legal
ownership.
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PDF |
Portable Document Format. A proprietary file format from Adobe which creates
lightweight text-based, formatted files for distribution to a variety of operating
systems.
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pixel |
The smallest element of a display device, such as a video monitor, that can be
independently assigned attributes, such as color and intensity. The term is an
abbreviation for picture element. Also, the smallest unit of information in an image
or raster map. Usually square or rectangular, pixel is often used synonymously with
cell.
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planar coordinate system |
A two-dimensional measurement system that locates features on a map based on their
distance from an origin (0,0) along two axes, a horizontal x-axis representing east-west
and a vertical y-axis representing north-south.
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plat |
A survey diagram, drawn to scale, of the legal boundaries and divisions of a tract of land.
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point |
A point normally represents a geographic feature too small to be displayed as a line or
area; for example, the location of a building location on a map.
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polygon |
A closed, two-dimensional figure with at least three sides that represents an area. It is
used in GIS to describe spatial elements with a discrete area, such as parcels, political
districts, areas of homogeneous land use and soil types.
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prime meridian |
In a coordinate system, any line of longitude designated as 0 degrees east and west, to
which all other meridians are referenced.
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Q
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query |
A statement expressing a set of conditions that forms the basis for the retrieval of
information from a database.
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R
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radius |
The distance from the center to the outer edge of a circle or circular curve.
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rubberbanding |
The process of click-n-dragging the cursor to form a box and then the elements of that
area are displayed or used in an application.
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S
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scale |
The relationship between distances on a map and the corresponding distances on the
earth's surface expressed as a fraction or a ratio. One unit of measurement on the
map -- 1 inch or 1 centimeter -- could represent 10,000 of the same units on the ground.
This would be a 1:10,000 scaled map.
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spatial data |
Any information about the location and shape of, and relationships among, geographic
features.
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State Plane Coordinate System |
A projected coordinate system used in the United States that divides each state into one
or more zones to minimize distortion caused by the map projection. Also known as SPCS and
SPC.
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symbol |
A graphic pattern used to represent a geographic feature on a map. For example, line
symbols represent linear features; various marker symbols can represent points; shade
symbols can represent areas; and text symbols, annotations. Many characteristics define
symbols, including color, size, shape, angle and pattern.
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T
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theme |
A user-defined perspective for geographic data.
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tract |
A small, relatively permanent statistical subdivision of a county. Tract boundaries
normally follow visible features, but may follow governmental unit boundaries or other
non-visible features. Designed to be relatively homogeneous units with respect to
population characteristics, economic status and living conditions at the time of
establishment, census tracts average approximately 4,000 inhabitants.
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U
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United States Geological Survey - USGS |
National mapping agency of the United States. Produces paper maps, digital maps and DEMs
for the entire nation at a variety of scales, including 1:24,000, 1:100,000, 1:250,000
and 1:1 million.
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V
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vertex |
One of a set of ordered X,Y coordinates that defines a line or polygon feature.
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W
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World Wide Web Consortium (W3C)
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An organization that develops standards for the World Wide Web and promotes
interoperability between Web technologies, such as browsers. Members from around the
world contribute to standards for XML, XSL, HTML and many other Web-based protocols.
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X
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x,y coordinates |
A pair of values that represents the distance from an origin (0,0) along two axes, a horizontal axis (x) representing east-west, and a vertical axis (y) representing north-south. On a map, x,y coordinates are used to represent features at the location they are found on the earth's spherical surface. |
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x-axis |
In a planar coordinate system, the horizontal line that runs right and left (east and
west of) the origin (0,0). On a chart, the horizontal axis.
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Y
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y-axis |
In a planar coordinate system, the vertical line that runs above and below (north and
south of) the origin (0,0). Numbers north of the origin are positive, and numbers south
of it are negative.
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Z
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zoom in |
A map tool that allows you to zoom in (and re-center the map) on the position on the map
where you click, or to an area you define by dragging a box in the map. The Zoom-In tool
is turned on by default when you start the application.
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zoom out |
This tool allows you to zoom out (and re-center the map) from the position on the map where you click, or from an area you define by dragging a box in the map. |
