Aerial photography
The process of taking photographs from a camera mounted in an airplane or balloon. The resulting photographs may be classified as vertical or oblique depending on the angle of the camera with respect to the Earth's surface at the time of exposure. Aerial photographs are used extensively in cartography to provide detailed geographical information in the production of base maps.
Aeronautical chart
A chart or map used for air navigation, which provides the aircraft pilot with important information about flight paths, airport approaches and facilities, as well as landmark features. In Canada, the federal government agency responsible for the supply of aeronautical information is the Aeronautical Charts Service of Geomatics Canada, Natural Resources Canada.
Astrolabe A navigational instrument used to measure the vertical angle between the horizon or the horizontal plane at the observer, and a celestial feature. An astrolabe is used to determine the geographic coordinates of points on the Earth's surface.
Atlas
A collection of maps in book or loose-leaf form, with a standard design, organized around a coherent theme. For example, a world atlas, a national atlas, or an historical atlas.
Azimuth
From the Arabic, "al-samt" meaning the way, the direction or the arc. A horizontal angle of direction calculated clockwise from the meridian plane. Azimuthal compass direction is expressed in terms of all 360° of a circle. The term can also be called magnetic azimuth, when calculated using the North or South magnetic poles.
Base map
A map which depicts fundamental information about the Earth's surface, such as landforms, drainage, landmark features and political boundaries. Many features are identified by geographical names or labels. Base maps usually come in a series and are used as a locational reference base for thematic information. Smaller scale regional reference maps are often derived from these bases. Topographic and planimetric maps are examples of base maps.
Bathymetry
The science of measuring the depth of bodies of water in order to determine underwater topography. A bathymetric map shows the topographic contours of the bottom of a body of water. A bathymetric chart, in addition, provides navigational information. (See Hydrographic chart).
Bearing
The horizontal angle measured from a point on a line of known direction (usually North) to another line extending from the same point of observation. If the angle is measured clockwise from the North it is called bearing East and when measured counter-clockwise it is called bearing West. For the mariner's and surveyor's compass, direction is measured in terms of the quadrant, and is never greater than 90°. Bearings can be measured from true North, grid North or magnetic North. The terms bearing and heading have the same definition, except bearing should refer to a fixed position, whereas, heading refers to the direction in which an object moves.
Cadastral map
A map showing the boundaries of property ownership, including tracts or parcels of land, and/or governmental administrative units.
Cardinal direction
A verbal expression of direction. One of the astronomical directions on the Earth's surface: North, South, East, or West.
Cartesian coordinate system
A coordinate system consisting of intersecting straight lines called axes, in which the lines intersect at a common origin. Usually it is a 2-dimensional surface in which a "x,y" coordinate defines each point location on the surface. The "x" coordinate refers to the horizontal distance and the "y" to vertical distance. Coordinates can be either positive or negative, depending on their relative position from the origin. In a 3-dimensional space, the system can also include a "z" coordinate, representing height or depth. The relative measurement of distance, direction and area are constant throughout the surface of the system.
Cartogram
A diagram or abstract map, not to scale, showing quantitative data, by distorting or exaggerating the size of areas.
Cartography
The art, science, and technology of map design and production. Cartography applies the fundamental scientific procedures of accurate measurement, classification, and the identification of relationships, to create visual models of our complex world. Traditional or conventional cartography refers to the preparation of maps through manually prepared overlays. Computer assisted (automated) cartography is less precisely defined but involves the extensive use of computer software and hardware in the preparation of map overlays. (See Automated cartography).
Cartouche
A decorative frame or graphic ornamentation on or surrounding a map, mainly associated with the title or legend. Used frequently on old maps and charts, but rarely used on maps today.
Chain
Unit of length equal to 66 feet, used especially in the U.S. public land surveys. The original measuring instrument (Gunter's chain) was literally a chain consisting of 100 iron links, each 7.92 inches long. Steel-ribbon tapes began to supersede chains around 1900, but surveying tapes are often still called "chains" and measuring with a tape is often called "chaining." The chain is a convenient unit in cadastral surveys because 10 square chains equal 1 acre.
Chart
A class of map designed primarily for use in air or water navigation. The term also applies to astronomical maps.
Compass
An instrument for drawing and measuring circles, consisting of two legs connected at one end by a movable joint. (See Cardinal direction, Compass point and Compass rose).
Compass bearing
The horizontal angle of direction measured from magnetic north as indicated by a compass and expressed in terms of cardinal direction, and degrees of a quadrant, (no greater than 90°). This term indicates a direction which is not corrected for magnetic declination.
Compass (direction)
An instrument, which indicates the direction of magnetic North, by means of a pivoting magnetic needle mounted on a circular dial or card. The dial or card indicates the cardinal directions, and can also have directions shown as compass points (up to 32) or in degrees (360°).
Compass point
A unit of compass direction. One of the 32 divisions of the circular dial or card of a compass, equal to 11°15' or 11.25° of a circle.
Compass rose
A circle drawn on a map, (usually a navigational chart) which is subdivided in a clockwise direction from 0° to 360° , with 0° indicating true North. On older maps and charts, it was a decorated diagram of cardinal directions, divided into 32 points, originally called rosa ventorum, or "rose of the winds".
Conic map projections
A group of map projections which are derived from the concept of projecting the parallels and meridians of a globe on to a tangent or secant cone which is then cut lengthwise and unrolled into a flat map. The principal scale is preserved along the standard parallels.
Cylindrical map projections
A group of map projections which are derived from the concept of projecting the parallels and meridians of a globe on to a tangent or secant cylinder which is then cut lengthwise and unrolled into a flat map. The principal scale is preserved along a line that represents a great circle.
Demographic map
A thematic map depicting the phenomena of human population, such as size, distribution, density, and condition.
Electoral map
A special purpose or thematic map showing the boundaries and names of electoral districts or ridings. Also, a map (at a national or regional scale) showing the results of an election, usually indicating by area colour, the political party that won each district.
Elevation
The vertical distance of a point or object above or below a reference surface or datum (usually mean sea level). Also referred to as altitude or height.
Gazetteer
A list of geographical place or feature names in alphabetical order, usually accompanied by geographic or grid coordinates and basic information about the feature, such as population or classification.
Geographic Information System (GIS)
A computer-based information system designed to handle georeferenced data which has also the capability to efficiently capture, store, update, manipulate, analyze, display and output a full range of geographical data. Output can be in many forms: either as tables, graphics, or maps.
Georeference
The process of establishing a relationship between data in Cartesian coordinates on a flat map to known ground-truth geographic coordinates.
Globe
A scaled down spherical representation or model of the Earth. A map on a sphere.
Gravure
A method of printing in which the image is etched into the surface of the printing plate and is therefore, recessed below the surface of the plate. Ink is captured in the recesses of the image and is transferred to paper under firm pressure. (Also called photogravure).
Hachures
A short line on a relief map that shows the downhill direction of a slope. The thickness and spacing of these lines indicate the relief. The steeper the slope the thicker the line. This method of relief portrayal is rarely used on today's maps; it has been replaced by contours, shading and hypsometric tints.
Hydrographic chart
A map used for the navigation of waterways. Features usually shown are: bathymetric contours, navigational hazards, aids to navigation, port facilities, water depths and type of shoreline.
Hypsometric tints
A method of depicting relief (or depth of water) on maps by using a gradation of different colours or tints, usually between contour lines. Each band of colour represents a different range of elevation or depth in reference to a specified surface, or datum.
Inset map
(1) A map located within the border of a larger map depicting an area of the main map at a larger scale. (2) A small scale key map (located in the surround) showing the area of the main map in the context of a greater region. (3) A map showing a region outside the main map that is significant to the theme of the principal map.
Latitude
Part of a spherical reference system used to locate positions on the surface of the Earth. The angular distance in degrees, minutes, and seconds measured from the centre of the Earth to a point north and south of the Equator.
Legend
A description or explanation of the symbology and other information printed on a map, chart or diagram, to provide a better understanding and interpretation of the data portrayed. Usually located in the margin.
Longitude
Part of a spherical reference system used to locate positions on the surface of the Earth. The angular distance in degrees, minutes, and seconds measured from the centre of the Earth to a point east and west of the Greenwich Meridian (prime or international meridian).
Manuscript, map
The original drawing of a map as compiled from various sources of information, including air photo, base map, thematic and toponymic data. It may be a single drawing, or consist of several overlays of information all in register and on the same base.
Map
A graphic representation (most commonly on a flat surface) of the spatial organization of any part of the physical universe at any scale, which symbolizes a wide variety of information, both static and dynamic.
Mapping
The process of making maps, including the collection of geographic information, design and production. (See Cartography).
Map projection
The process of systematically transforming positions on the Earth's spherical surface to a flat map while maintaining spatial relationships. This process is accomplished by the use of geometry or, more commonly, by mathematical formulas. Map projection can be best visualized by imagining a light bulb placed at the centre of a transparent globe and having its lines of longitude and latitude cast upon either a flat sheet of paper or a sheet of paper rolled into a cylinder or cone placed over the globe.
Map scale
A ratio representing the relationship between a specified distance on a map and the actual distance on the ground. For example, at the scale of 1:50 000, 1 unit of measurement on the map equals 50 000 units of the same measurement on the ground. Map scale is frequently expressed as a representative fraction and graphically as a bar scale. (See Bar scale, Representative fraction and Verbal scale).
Mercator projection
A cylindrical map projection introduced in 1569 by the famous Flemish mathematician and geographer Gerhard Mercator. Originally named Gerhard Krämer (meaning "trader" in German), his name was latinized (a fashionable practice among scholars of the day) to Mercator, meaning "world-trader". This conformal projection is still commonly used for world maps, on which rhumb lines are represented as straight lines, making this projection very useful for navigation. (See Conformal and Rhumb line).
Meridian
A line of longitude on a spherical grid reference system. Meridians also form great circles passing through the North and South Poles. Meridian is often used as a synonym for "line of longitude" thus, 100th meridian, or Greenwich Meridian. (See Central meridian and Greenwich Meridian).
Mosaic, aerial
A set of aerial photographs arranged, aligned and assembled to form a continuous view of a portion of the Earth's surface. The edges of individual photographs are usually cut and peeled back in order to facilitate a smooth transition for the overlap with adjoining photos.
Orthographic map projection
A planar map projection which is tangent to the globe at a single point, but may be oriented at any aspect. The projection views the Earth from an infinite point in space. In the polar case, parallels are represented by a system of concentric circles sharing a common point of origin from which radiate the meridians, spaced at true angles. This projection shows true direction, but only between its centre and other locations on the same map.
Orthophoto map
A map produced from a mosaic of orthophotographs, to which has been added a grid, cartographic symbology and sometimes colour.
Overlay
In traditional cartography, a drawing or graphic compilation of geographically related data symbolized on transparent or translucent material, usually in register with a base map. One or more overlays of information in register combine to form a map mauscript. In automated cartography, overlays will normally be digital map files which can be registered and combined to form a complete map.
Perspective map
A flat map which has been modified in order to depict features as if they were seen from an oblique angle rather than from overhead.
Perspective projection
A simple geometric map projection in which the surface of the Earth is transformed to one of three developable surfaces; the plane, cylinder, or cone. Most map projections can be described and categorized according to from which geometric surface they are derived. The point of perspective of most projections is at the centre of the Earth. However, with the planar family of map projections the point of perspective may also be a location opposite to the point of tangency or from an external point, as if the Earth were viewed from outer space.
Photomap
A map produced from a mosaic of aerial photographs fitted to ground control and overprinted with cartographic symbology, a reference grid and surround information.
Physiographic map
A map showing landforms and/or landform regions. Terrain may be represented using 3-dimensional symbology, such as relief shading or by elevation contours, hypsometric tints, or a combination of all. Area colours and type may be used to identify landform regions. (Also called a geomorphological map).
Plan
(1) The most simple form of a map: it is a map or diagram showing only the relative horizontal position of basic features, and is not necessarily to scale. (2) A set of procedures, tasks, or method of action leading to the completion of a project.
Planar map projections
A group of map projections which are derived from the concept of projecting the parallels and meridians of a globe on to a tangent plane, resulting in a flat map. The point of tangency to the globe specifies the aspect of this map projection (polar, equatorial, or oblique). The point of perspective determines the amount of distortion towards the periphery of the graticule. (Also called an azimuthal or zenithal map projection due to its property of true direction).
Planimetric map
A map which represents only the horizontal positions of geographic features as opposed to a topographic map which also shows vertical data or relief. Features usually shown on a planimetric map include roads, railways, rivers, populated places and boundaries.
Reference map
A type of map showing the prominent geographical features of an area. These maps usually depict fundamental information about the Earth's surface such as landforms and drainage, at the same time symbolizing landmark culture features such as roads, railways and populated places. Many features are identified by geographical names and labels. This class of map is used for planning, location and reference purposes, and may also be used as a base map for thematic information.
Relief
The physical surface of the Earth including the elevations and depressions of the land and ocean floor. Relief is represented on maps by contours, hypsometric tints, shading, digital terrain modeling, or spot elevations.
Relief shading
A method of depicting relief on maps by drawing dark and light shadows on slopes to indicate the degree of slope, as if shadows were cast by the relief. Relief shading creates a 3-dimensional effect. The illumination for the relief drawing usually comes from the northwest corner of the map. Contour lines, aerial photography, spot elevations and drainage are used as guides for shading. Relief shading is drawn in pencil and highlights are added using an airbrush.
Rhumb line
A curved line on the Earth's surface that crosses all meridians at the same oblique angle. Also called a loxodromic curve. On the Mercator map projection, rhumb lines are represented by straight lines that follow constant compass direction or bearing, making this projection very useful for navigation.
Sextant
A hand-held instrument used for navigation and surveying when it is not convenient to use a theodolite or transit. A sextant is used to measure the angle at the point of observation between a celestial object and the horizon, or between two objects. The angle is measured on a graduated arc covering 1/6 of a full circle or 60°, hence the name "sextant".
Stereographic map projection
A planar map projection which is tangent to the globe at a single point, but may be oriented at any aspect. The projection views the Earth's surface from the point on the globe opposite the point of tangency. In the polar case, parallels are represented by a system of concentric circles sharing a common point of origin from which radiate the meridians, spaced at true angles. This projection shows true direction, but only between its centre and other locations on the same map, and is the only planar map projection that is conformal.
Thematic map
A class of map showing the spatial distribution of a particular phenomenon in qualitative or quantitative graphic form. The opposite of a base or reference map (which shows only fundamental information about the Earth's surface and are used as a locational reference base for thematic data). Almost any subject that can be expressed as a geographical distribution can be mapped. Examples of thematic map subjects include population, precipitation, vegetation, exploration, and employment.
Topographic map
A class of map designed primarily for the purpose of depicting elevation (relief), as opposed to a planimetric map which only shows the horizontal location of geographic features. Topographic maps show vertical data with contour lines, hypsometric tints, spot heights, and relief shading. Also shown is fundamental information about the Earth's surface such as landforms, vegetation, and drainage. Cultural and landmark features, such as roads, railways, populated places, and buildings are often included.
Source of terms: Natural Resources Canada (link out of date, no replacement available) http://atlas.nrcan.gc.ca/site/english/learningresources/glossary/index.html