Map


A map is a symbolic depiction of interrelationships, commonly spatial, between things within a space. A map may be annotated with text and graphics. Like any graphic, a map may be fixed to paper or other durable media, or may be displayed on a transitory medium such as a computer screen. Some maps change interactively. Although maps are commonly used to depict geographic elements, they may represent any space, real or fictional. The subject being mapped may be two-dimensional such as Earth's surface, three-dimensional such as Earth's interior, or from an abstract space of any dimension.
Maps of geographic territory have a very long tradition and have existed from ancient times. The word "map" comes from the, wherein mappa meant 'napkin' or 'cloth' and mundi 'of the world'. Thus, "map" became a shortened term referring to a flat representation of Earth's surface.

History

Maps are a widespread invention, having been found in several societies across the world even before the development of other written communication systems. The earliest surviving maps include cave paintings and etchings on tusk and stone. Later came extensive maps produced in ancient Babylon, Greece and Rome, China, and India. In their simplest forms, maps are two-dimensional constructs. Since the Classical Greek period, however, maps also have been projected onto globes. The Mercator Projection, developed by Flemish geographer Gerardus Mercator, was widely used as the standard for two-dimensional world maps until the late 20th century, when more accurate projections were more widely used. Mercator also was the first to use and popularize the concept of the atlas: a collection of maps.

Geography

or map-making is the study and practice of crafting representations of the Earth upon a flat surface, and one who makes maps is called a cartographer or mapmaker.
Road maps are perhaps the most widely used maps today. They are a subset of navigational maps, which also include aeronautical and nautical charts, railroad network maps, and hiking and bicycling maps. In terms of quantity, the largest number of drawn map sheets is probably made up by local surveys, carried out by municipalities, utilities, tax assessors, emergency services providers, and other local agencies. Many national surveying projects have been carried out by the military, such as the British Ordnance Survey: a civilian government agency, internationally renowned for its comprehensively detailed work.
The location information showed by maps may include contour lines, indicating constant values of elevation, temperature, rainfall,
Scholars of critical geography, including John Brian Harley, have posited that all maps are charged with rhetorical biases and should therefore be viewed with a level of skepticism. These scholars argue that maps can change or enforce a certain view of a place by changing the viewer's perspective of the world. For example, Americans widely thought that they were insulated from European conflicts by the Atlantic and Pacific Oceans before aviation maps highlighted the closeness between North America and Europe across the North Pole. The social power of maps has given rise to an entire study of how maps can alter human perspectives of the globe.

Orientation

The orientation of a map is the geographical direction toward the top of the map. In the Middle Ages many Eurasian maps, including the T and O maps, were drawn with east at the top. The word "orient" is derived from Latin oriens, meaning east. The modern cartographic convention is to put north at the top of a map. This convention is only a few hundred years old.
As no direction is inherently "up" on a spheroidal planet, a variety of orientations have been used on maps both historically and in the present day. Different factors may influence the preferred orientation of a map, depending both on its expected use and cultural factors affecting the perception of each direction. For instance, north and west had historically not been placed at the top of maps made in the Northern Hemisphere as these were the directions where the sun disappeared.
Many maps were oriented to place a particularly significant or holy site at the top. Early Islamic maps often placed south at the top because this was the direction of Mecca relative to the map-makers. Similarly, European Christian maps like the T-O map placed east at the top as this was the direction of the Garden of Eden. Early Chinese maps placed north at the top due to the location of the imperial capital.
Other examples of maps with non-north orientations include:
  • Portolan charts are oriented to the shores they describe.
  • Maps of cities bordering a sea are often conventionally oriented with the sea at the top.
  • Route and channel maps have traditionally been oriented to the road or waterway they describe.
  • Polar maps of the Arctic or Antarctic regions are conventionally centered on the pole; the direction North would be toward or away from the center of the map, respectively. Typical maps of the Arctic have 0° meridian toward the bottom of the page; maps of the Antarctic have the 0° meridian toward the top of the page.
  • South-up maps invert the North is up convention by having south at the top. Ancient Africans including in Ancient Egypt used this orientation, as some maps in Brazil do today.
  • Buckminster Fuller's Dymaxion maps are based on a projection of the Earth's sphere onto an icosahedron. The resulting triangular pieces may be arranged in any order or orientation.
  • Orienteering maps are oriented to magnetic north.

    Scale and accuracy

Many maps are drawn to a scale expressed as a ratio, such as 1:10,000, which means that 1 unit of measurement on the map corresponds to 10,000 of that same unit on the ground. The scale statement can be accurate when the region mapped is small enough for the curvature of the Earth to be neglected, such as a city map. Mapping larger regions, where the curvature cannot be ignored, requires projections to map from the curved surface of the Earth to the plane. The impossibility of flattening the sphere to the plane without distortion means that the map cannot have a constant scale. Rather, on most projections, the best that can be attained is an accurate scale along one or two paths on the projection. Because scale differs everywhere, it can only be measured meaningfully as point scale per location. Most maps strive to keep point scale variation within narrow bounds. Although the scale statement is nominal it is usually accurate enough for most purposes unless the map covers a large fraction of the Earth. At the scope of a world map, scale as a single number is practically meaningless throughout most of the map. Instead, it usually refers to the scale along the equator.
Some maps, called cartograms, have the scale deliberately distorted to reflect information other than land area or distance.
Another example of distorted scale is the famous London Underground map. The geographic structure is respected but the tube lines are smoothed to clarify the relationships between stations. Near the center of the map, stations are spaced out more than near the edges of the map.
Further inaccuracies may be deliberate. For example, cartographers may simply omit military installations or remove features solely to enhance the clarity of the map. For example, a road map may not show railroads, smaller waterways, or other prominent non-road objects, and even if it does, it may show them less clearly than the main roads. Known as decluttering, the practice makes the subject matter that the user is interested in easier to read, usually without sacrificing overall accuracy.

Projection

Geographic maps use a projection to translate the three-dimensional real surface of the geoid to a two-dimensional picture. Projection always distorts the surface. There are many ways to apportion the distortion, and so there are many map projections. Which projection to use depends on the purpose of the map.

Symbols

The various features shown on a map are represented by conventional signs or symbols. For example, colors can be used to indicate a classification of roads. Those signs are usually explained in a map legend on the margin of the map, or on a separately published characteristic sheet.
Some cartographers prefer to make the map cover practically the entire screen or sheet of paper, leaving no room "outside" the map for information about the map as a whole. These cartographers typically place such information in an otherwise "blank" region "inside" the mapcartouche, map legend, title, compass rose, bar scale, etc.
In particular, some maps contain smaller maps inset into otherwise blank areas of the map: for example:
  • a map at a much smaller scale showing the whole globe and the position of the main map on that globe, or
  • showing "regions of interest" at a larger scale to show details that would not otherwise fit, or
  • showing places that do not fit on the main map, such as Alaska and Hawaii on maps of the United States, or the Shetland and Orkney Islands on maps of Britain.

    Design

The design and production of maps is a craft that has developed over thousands of years, from clay tablets to geographic information systems. As a form of design, particularly closely related to graphic design, map making incorporates scientific knowledge about how maps are used, integrated with principles of artistic expression, to create an aesthetically attractive product, carries an aura of authority, and functionally serves a particular purpose for an intended audience.
Designing a map involves bringing together a number of elements and making a large number of decisions. The elements of design fall into several broad topics, each of which has its own theory, its own research agenda, and its own best practices. That said, there are synergistic effects between these elements, meaning that the overall design process is not just working on each element one at a time, but an iterative feedback process of adjusting each to achieve the desired gestalt.
  • Map projections: The foundation of the map is the plane on which it rests, but projections are required to flatten the surface of the Earth. All projections distort this surface, but the cartographer can be strategic about how and where distortion occurs. Distortion is argued to be one of the main sources of bias in mapping.
  • Generalization: All maps must be drawn at a smaller scale than reality, requiring that the information included on a map be a very small sample of the wealth of information about a place. Generalization is the process of adjusting the level of detail in geographic information to be appropriate for the scale and purpose of a map, through procedures such as selection, simplification, and classification.
  • Symbology: Any map visually represents the location and properties of geographic features using map symbols, graphical depictions composed of several visual variables, such as size, shape, color, and pattern.
  • Composition: As all of the symbols are brought together, their interactions have major effects on map reading, such as grouping and Visual hierarchy.
  • Typography or Labeling: Text serves a number of purposes on the map, especially aiding the recognition of features, but labels must be designed and positioned well to be effective.
  • Layout: The map image must be placed on the page, along with related elements, such as the title, legend, additional maps, text, images, and so on. Each of these elements has its own design considerations, as does their integration, which largely follows the principles of Graphic design.
  • Map type-specific design: Different kinds of maps, especially thematic maps, have their own design needs and best practices.
  • Map extent: it is the portion of area of a region shown in a map. The limits of a map extent are defined in the coordinate system of the map. In Western culture, map extents usually have a rectangular shape, so they are defined with a minimum and maximum width and height.