MAP


A 'map' is a visual representation of an area—a symbolic depiction highlighting relationships between elements of that space such as objects, regions, and themes.
Many maps are static two-dimensional, geometrically accurate representations of three-dimensional space, while others are dynamic or interactive, even three-dimensional. Although most commonly used to depict geography, maps may represent any space, real or imagined, without regard to context or scale; e.g. Brain mapping, DNA mapping, and extra-terrestrial mapping.

Contents
Geographic maps
Orientation of maps
Scale and accuracy
World maps and projections
Electronic maps
References
See also
External links
Map discussion and history
Map link sites
Modern maps and atlases online
Antique and historical maps online
Online map creation tools

Geographic maps


A celestial map from the 17th century, by the Dutch cartographer Frederik de Wit.

Cartography, or ''map-making'' is the study and, often, practice, of crafting representations of the Earth upon a flat surface (see History of cartography), and one who makes maps is called a ''cartographer''. Cartography is evident as early as the Stone Age and appears to predate written language by several millennia.
One of the oldest surviving maps, dated approximately 6200 BC [1], is painted on the wall of the Catal Huyuk settlement in South-central Anatolia, or what is now Turkey.
While we tend to think of maps today as products of a rationalistic, scientific world-view, maps also have a mythic quality. Pre-modern maps, and mapping traditions outside the Western tradition, often merge geography with non-scientific cosmography, showing the relationship of the viewer to the universe. Medieval "T-O" maps, for example, show Jerusalem at the centre of the world, and in some cases related the "body" of the Earth to the body of Christ. By contrast, navigational (or "Portolan") charts of the Mediterranean from the same period are remarkably accurate. Even today, maps can be powerful rhetorical tools beyond their purely practical value, and this has been the source of much fruitful map criticism over the last twenty years, notably in the works of J.B. Harley, Mark Monmonier, and Denis Wood.
Physical map of the Earth.

Geographic maps are abstract representations of the world. It is, of course, this abstraction that makes them useful. Lewis Carroll made this point humorously in ''Sylvie and Bruno'' with his mention of a fictional map that had "the scale of a mile to the mile". A character notes some practical difficulties with this map and states that "we now use the country itself, as its own map, and I assure you it does nearly as well". This concept is elaborated in a one-paragraph story by Jorge Luis Borges, generally known in English as "On Exactitude in Science".
Road maps are perhaps the most widely used maps today, and form 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 (now a civilian government agency internationally renowned for its comprehensively detailed work).

Orientation of maps



The term orientation refers to the relationship between directions on a map and compass directions. The word orient is derived from oriens, meaning east. In the Middle Ages many maps, including the T and O maps, were drawn with east at the top. Today the most common, but far from universal, cartographic convention is that North is at the top of a map. Examples of maps not orientated to north are:

Polar maps of the Arctic or Antarctic regions are conventionally centered on the pole, in which case the direction north would be towards or away from the center of the map, respectively.

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.

★ Maps from non-Western traditions are oriented a variety of ways. Old maps of Edo show the Japanese imperial palace as the "top," but also at the centre, of the map. Labels on the map are oriented in such a way that you cannot read them properly unless you put the imperial palace above your head.

Medieval European T and O maps such as the Hereford Mappa Mundi were centred on Jerusalem with east at the top. Indeed, prior to the reintroduction of Ptolemy's ''Geography'' to Europe around 1400, there was no single convention in the West. Portolan charts, for example, are oriented to the shores they describe.

★ Route and channel maps have traditionally been oriented to the road or waterway they describe.

★ Many maps used in the Society for Creative Anachronism show the west at the top, in honor of the Society starting in California.

Scale and accuracy


Many but not all maps are drawn to a scale, allowing the reader to infer the actual sizes of, and distances between, depicted objects. A larger scale shows more detail, thus requiring a larger map to show the same area. For example, maps designed for the hiker are often scaled at the ratio 1:24,000, meaning that 1 of any unit of measurement on the map corresponds to 24,000 of that same unit in reality; while maps designed for the motorist are often scaled at 1:250,000. Maps which use some quality other than physical area to determine relative size are called cartograms.
A famous example of a map without scale is the London Underground map, which best fulfils its purpose by being less physically accurate and more visually communicative to the hurried glance of the commuter. This is not a cartogram (since there is no consistent measure of distance) but a topological map that also depicts approximate bearings. The simple maps shown on some directional road signs are further examples of this kind.
In fact, most commercial navigational maps, such as road maps and town plans, sacrifice an amount of accuracy in scale to deliver a greater visual usefulness to its user, for example by exaggerating the width of roads. With the end-user similarly in mind, cartographers will censor the content of the space depicted by a map in order to provide a useful tool for that user.
For example, a road map may or may not show railroads, and if it does, it may show them less clearly than highways.
Some maps such as topographical maps show constant values such as elevation, these are often represented, along with other characteristics, depending on the scale of the map, in the form of Isolines. Isolines on a map or chart indicate a constant value such as temperature, pressure, or rainfall.

World maps and projections


Main articles: World map

Map of large underwater features. (1995, NOAA)

Maps of the world or large areas are often either 'political' or 'physical'. The most important purpose of the political map is to show territorial borders; the purpose of the physical is to show features of geography such as mountains, soil type or land use. Geological maps show not only the physical surface, but characteristics of the underlying rock, fault lines, and subsurface structures.
Maps that depict the surface of the Earth also use a projection, a way of translating the three-dimensional real surface of the geoid to a two-dimensional picture. Perhaps the best-known world-map projection is the Mercator Projection, originally designed as a form of nautical chart.
Airplane pilots use aeronautical charts based on a Lambert conformal conic projection, in which a cone is laid over the section of the earth to be mapped. The cone intersects the sphere (the earth) at one or two parallels which are chosen as standard lines. This allows the pilots to plot a great-circle route approximation on a flat, two-dimensional chart.

Azimuthal or Gnomonic map projections are often used in planning air routes due to their ability to represent great circles as straight lines.

Richard Edes Harrison produced a striking series of maps during and after World War II for Fortune magazine. These used "bird's eye" projections to emphasize globally strategic "fronts" in the air age, pointing out proximities and barriers not as apparent on a conventional rectangular projection of the world.

Electronic maps



From the last quarter of the 20th century, the indispensable tool of the cartographer has been the computer. Much of cartography, especially at the data-gathering survey level, has been subsumed by Geographic Information Systems (GIS). The functionality of maps has been greatly advanced by technology allowing, for example, the superimposition of spatially located variables onto existing geographical maps. Having local information such as rainfall level, distribution of wildlife, or demographic data integrated within the map makes for more efficient analysis and better decision making. In the pre-electronic age such superimposition of data led to Dr. John Snow discovering the cause of cholera. Today, it is used by agencies as diverse as wildlife conservationists and militaries around the world.
Even when GIS is not involved, most cartographers now use a variety of computer graphics programs to generate new maps.
Interactive, computerised maps are commercially available, allowing users to ''zoom in'' or ''zoom out'' (respectively meaning to increase or decrease the scale), sometimes by replacing one map with another of different scale, centred where possible on the same point. In-car satellite navigation systems are computerised maps with route-planning and advice facilities which monitor the user's position with the help of satellites. From the computer scientist's point of view, zooming in entails one or a combination of:
#replacing the map by a more detailed one
#enlarging the same map without enlarging the pixels, hence showing more detail by removing less information compared to the less detailed version
#enlarging the same map with the pixels enlarged (replaced by rectangles of pixels); no additional detail is shown, but, depending on the quality of one's vision, possibly more detail can be seen; if a computer display does not show adjacent pixels really separate, but overlapping instead (this does not apply for an LCD, but may apply for a cathode ray tube), then replacing a pixel by a rectangle of pixels does show more detail. A variation of this method is interpolation.
For example:

★ Typically (2) applies to a Portable Document Format (PDF) file. The increase in detail is, of course, limited to the information contained in the file: enlargement of a curve may eventually result in a series of standard geometric figures such as straight lines or arcs of circles.

★ (2) may apply to text and (3) to the outline of a map feature such as a forest or building.

★ (1) may apply to the text (displaying labels for more features), while (2) applies to the rest of the image. Text is not necessarily enlarged when zooming in. Similarly, a road represented by a double line may or may not become wider when one zooms in.

★ The map may also have layers which are partly raster graphics and partly vector graphics. For a single raster graphics image (2) applies until the pixels in the image file correspond to the pixels of the display, thereafter (3) applies.
See also Webpage (Graphics), PDF (Layers), Mapquest, Google Maps, Google Earth or Yahoo! Maps.

References


1.
Miles Harvey, ''The Island of Lost Maps: A True Story of Cartographic Crime''. New York : Random House, 2000 ISBN 0-7679-0826-0, cited above; also ISBN 0-375-50151-7


★ David Buisseret, ed., ''Monarchs, Ministers and Maps: The Emergence of Cartography as a Tool of Government in Early Modern Europe.'' Chicago: University of Chicago Press, 1992, ISBN 0-226-07987-2

★ Mark Monmonier, ''How to Lie with Maps'', ISBN 0-226-53421-9

★ O'Connor, J.J. and E.F. Robertson, ''The History of Cartography''. Scotland : St. Andrews University, 2002.

★ Denis E. Cosgrove (ed.) ''Mappings''. Reaktion Books, 1999 ISBN 1-86189-021-4
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See also


; General

Atlas

Ancient world maps

Cartography

Geography

Globe

History of cartography


; Map design and types

Thematic map

Cartogram

Contour map

Dymaxion map

Floor plan

Geologic map

Map design

Nautical chart

Pictorial maps

Planform

Plat

Road atlas

Street map

Topographic map

World map
; Modern maps

Maps of the UK and Ireland

Maps of the United States

Google Maps

MapQuest

NASA World Wind

Japanese map symbols
; Map history

George Bradshaw, including maps of the British railway network, first published in 1839

Sanborn Maps - detailed American fire insurance maps

Ordnance Survey
; Related Topics

Aerial photography

Aerial landscape art

Orthophoto

Geography Cup

Map database management

External links


Map discussion and history


Geography and Maps, an Illustrated Guide, by the staff of the U.S. Library of Congress.

Antique Maps by Carl Moreland and David Bannister - complete text of the book

Map Room, a weblog about maps, with a links Directory

The Upsidedown Map Page Pictures and info about maps which are oriented without North at the top

Example of map legends (Cito-Plan city maps)

Wikipedia:Maps, use of maps on Wikipedia

slashgeo.org - Community-driven and ad-free website for news and discussions about Maps and Geospatial technologies

Getting There Article on Online Maps from The New Yorker
Map link sites


Perry-Castañeda Library, Maps on Other Web Sites

★ British Library links for historic maps and interactive mapping, both their own collections and other sites

Odden's Bookmarks, The fascinating world of maps and mapping, the world's largest map-related link collection.

University of Iowa Links, many map-related links

Online Map Catalogs in North America and Europe

Geographical data resources online

Primary sources for the research scholar, links to websites for archives of research material.

★ Soil Maps of the world European Digital Archive on the Soil Maps of the world

Maps and Routes - South America countries

Mapsarea.com Portal to the top sites for maps, atlases, and related topics.

1:25 000 Topographical Maps for NSW, Australia - Index links to detailed maps

Maps of Cyprus - High quality maps of Cyprus

Maps of Kola Peninsula (rus)

online maps,road maps,street maps in California
Modern maps and atlases online

World Maps and Atlases:

National Geographic Map Machine

Wild Finder-World Wildlife Fund

Shaded Relief

Perry-Castañeda Library, University of Texas

Google Maps

An interactive Java applet to study deformations (area, distance and angle) of map projections
Country Maps:

National Atlas of the United States

National Map, United States Geological Survey

TerraServer-USA and TopoZone host USGS topographic maps (and aerial photos on TerraServer-USA); Maptech hosts historical USGS topos in the northeast United States.

Atlas of Canada

Geography Network

Geospatial One-Stop - geodata.gov

Thematic maps of Australia

Maps of Poland

Maps of Turkey

Maps of Czech Republic

Maps of French territory
Antique and historical maps online


MAPCO : Map And Plan Collection Online, historic maps of London, the British Isles, and Australia c1560-1929

Historical map web sites list, Perry-Castañeda Library, University of Texas

Map history and collections introductory page and list of maps on the web organized by geographical region

Mapping History - a learning resource from the British Library

David Rumsey map collection, 12,600 maps online

Online map collections at the Library of Congress

Historical Maps from the Hargrett Library Collection (University of Georgia) - browse over 1000 maps from as early as 1544. DjVu format; requires free plugin or JAVA

Historical Maps from the Portal to Texas History

Antique maps of Europe and Mediterranean basin

Collection of maps of early European efforts to document the Southern Hemisphere - State Library of NSW

The Tasman Map - State Library of NSW

Historical Maps of Kola Peninsula (rus)
Online map creation tools


Map.TV A video portal about maps and travel

MyGuestmap: A free map creation tool for blogs and other personal websites

GetMapped: Service for pointing out visited cities and countries.

Online Map Creation: Webinterface to GMT mapping package; new version at Planiglobe Beta

OpenStreetMap The Free Wiki World Map

WikiMap A free Mapping with facility to add information and tools for planning.

Maptrot.com Easy to use customized Google Maps creator for sharing and embedding

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