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Map
A map is a symbolized depiction of a space which highlights relations
between components (objects, regions, themes) of that space. Most usually a
map is a two-dimensional, geometrically accurate representation of a
three-dimensional space; e.g., a geographical map. However, computers and
database systems have allowed for the growth of Geographic Information
Systems, or GIS, which allow for dynamic, real-time interaction with
geographic data. More generally, maps can be devised to represent any local
property of the world or part of it, or any other space, such as the brain
(see Brain mapping) or extra-terrestrial mapping.
Geographical maps
The science and art of map-making is cartography; see that page for further
discussion of the history of maps and map-making. Map-making dates back to
the Stone Age and appears to predate written language by several millennia.
One of the oldest surviving maps is painted on a wall of the Catal Huyuk
settlement in south-central Anatolia (now Turkey); it dates from about 6200
BC. [1] One who makes maps professionally or privately is called a
cartographer.
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.
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 the center
of the map.
* 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.
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 average
temperature, these are often represented, along with other characteristics,
depending on the scale of the map, in the form of Isolines. Isolines are
often on a map or chart along which there is constant value (temperature,
pressure, or rainfall).
World maps and projections
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:
1. replacing the map by a more detailed one
2. enlarging the same map without enlarging the pixels, hence showing more
detail by removing less information compared to the less detailed version
3. 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.
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
Map link sites
* Perry-Castaņeda 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
Modern maps and atlases online
World Maps and Atlases:
* National Geographic Map Machine
* Wild Finder-World Wildlife Fund
* Shaded Relief
* Perry-Castaņeda Library, University of Texas
* Google Maps
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
Antique and historical maps online
* Historical map web sites list, Perry-Castaņeda 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
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
* Stickymap: A collaborative global map where users can tag points of
interest to create customized maps.
* 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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