|Nature Gallery (Geography)|
What Is Cartography?
|Cartography is the art
and science of creating maps. It involves the gathering of geographical
information, the storage, processing, and editing of this information, and
the presentation of the data in map form. Cartography depends on sound
geographical knowledge of the surface being mapped, as well as the many
skills and tools instrumental to the mapping process.
|Cartography has been practiced
since ancient times. For many centuries its highest application was the
production of hand-drawn flat maps and charts assembled from information
collected visually by explorers, and other individuals. As a result, they
were not as accurate as modern maps, but are fascinating as a record of
the level of knowledge and thought at the time. Map reproductions were
also of great value because they were copied by hand.
Often these early maps were intended for specific purposes, usually for military campaigns or for delineating the boundaries of empires. The ancient Romans and Egyptians, who created maps for these purposes, were among the most scholarly cartographers of their time.
Today, as in ancient times, cartographers look for ways to make more accurate maps, methods to reproduce them more efficiently, and channels to distribute them more conveniently. During the history of cartography, map-making has evolved with technology.
The Influence of Technology
|The first major
technological advance in map-making was the invention of the printing
press, first in China in the 12th century
and later in Europe in the 15th century.
Printing allowed more maps to be made in a shorter period of time, which
increased their availability and lowered their cost. Prior to the European
Renaissance, the maps most European people were familiar with mixed
Biblical and other mythical themes with representations of real places.
Mythical figures were often used to represent unknown parts of the world.
However, advances in printing made it easier to produce maps for strictly
practical purposes, especially navigation, and exploration continually
reduced the extent of the unknown.
Maps both encouraged and facilitated exploration, which in turn stimulated cartographers to make more extensive and more accurate maps. The interplay between mapping and exploration can be seen in the rapidly increasing detail filling the maps made by Spanish adventurers in North America as they explored the continent between the 15th and 17th centuries.
Similarly, the initial drawings of the Caribbean Islands made by Columbus, and those of the California coast by Cortez, were little more than squiggly lines. But such crude maps helped guide the establishment of the Spanish New World Empire. By the time this empire had reached its maximum extent in North America, the maps had become far more detailed and sophisticated.
The next major advance in map-making technology came in the mid-1800s with the development of photography. Photography enabled cartographers to capture detailed surface data, and the invention of photogrammetry—using special cameras and image projectors to translate photographs into accurate survey maps—soon followed.
As photography became more practical and economical, its use in reproducing maps also grew in importance. The invention and refinement of modern printing methods towards the end of the 19th century—especially lithography, which allowed delicate detail and shading—provided the means to easily reproduce sophisticated maps.
Other factors contributing to the importance of cartography during the late 1800s and early 1900s included the development of public infrastructure in and around major cities. This growing infrastructure, especially the construction of transport systems, required extensive planning and mapping by civil authorities. The emergence of the field of statistics was also important to cartographers since it allowed them to translate difficult mathematical generalizations into symbolic geographical pictures, such as the distribution of population density in an urban area. Today, maps making geographical sense of complex statistical information on a certain theme are known as statistical or thematic maps. Also during this time cartographic societies began forming, lending additional authority to cartography as a profession.
Although cartographers found that recording data with photographs was relatively easy, the only way they could get an overview of the landscape for photogrammetric purposes was to climb a mountain or an observation tower. The advent of utilitarian hot-air balloons in the 1800s offered new promise, but the balloons proved difficult to control and the photographers’ cameras were not sophisticated enough to capture sufficient ground detail. Even worse, in wartime the balloons made easy targets for the enemy.
Technological advances in the early 20th century helped cartography make rapid progress. Smaller cameras gave photographers more mobility, and more sensitive film enabled exposures under a wider range of conditions. However, the greatest leap came with the invention of the aeroplane and true aerial photography. Detailed high-altitude photographs could be taken, making it easy to render accurate orthogonal (perpendicular to the earth) maps of relatively great extent, or fine detail. A fully equipped photographer was among the first passengers to fly in the Wright brothers’ experimental aircraft. Aerial reconnaissance became extremely important in both World War I and II, and today aerial photogrammetry remains the most popular means of remote data gathering for many types of map.
The Modern Era
|Since the mid-1900s
technology has helped professional cartography undergo rapidly
accelerating change. Photolithography and photoengraving have merged
photography with printing—high-speed multi-color lithographic offset
presses can rapidly produce maps of almost any degree of detail, color
scheme, or labeling requirement.
Technology known as remote sensing has also enabled modern cartographers to chart the depths of the ocean or the frontiers of outer space. The space programme has taken cameras into orbit, providing vast image collections of Earth, other planets, and even other galaxies.
Equally far-reaching advances in cartography have emerged from advances in electronic communication and various computer applications. Modern computers can store and transmit huge amounts of mapping data, and then control the assembly of such data producing maps using sophisticated digitizers, plotting machines, and electronic typography.
Information-gathering technology has produced advanced cameras that can transmit digital data from outer space, and maps which show nearly any place or geographic theme for which digital information can be retrieved. Geographic information systems (GIS), described below, are the most recent synthesis of these modern technologies.
Gathering Cartographic Information
|Traditional methods of
map-making involve character description and detailed positioning based on
ground observations. Today, ground observation is used primarily for
verifying the details of maps made using more sophisticated techniques.
Maps generated only by ground observations are still important but are
usually unofficial, for limited distribution, or they are local and small
scale, such as architectural plans and land surveys.
Conversely, data used to produce highly technical maps or maps made for wide distribution are typically collected with advanced technology such as aerial photogrammetry or remote sensing from low Earth orbit. The data are then processed and meticulously composed into the simplified illustrations we call maps.
Global Positioning Systems
Systems (GPS) are devices that give an Earth coordinate position based on
the reception of special satellite transmissions. The position is worked
out, by triangulation, based on the relative positions of at least three
satellites. Modern GPS units—some as small as cellular telephones—have
a simple LCD screen similar to that on an electronic calculator, and a
simple keyboard for entering codes. These hand-held instruments can be
programmed to record and display the exact position of the unit, the
user’s ground speed and direction of travel, and projected arrival times
at certain points along a chosen route.
The current system used for GPS is administered by the United States, although the European Space Agency has plans for a similar system. Because of military security concerns, the US government regulates the resolution of satellite transmissions available to the public for GPS use. Although GPS units are theoretically accurate to within several centimetres, their practical range today is about 3 to 30 metres (10 to 100 feet), not accurate enough for collecting precise map data. Another problem with using GPS to collect map data is that trees and steep terrain block the reception of satellite transmissions. The most common and rapidly growing use of GPS is in aircraft and ship navigation, and some vehicle manufacturers are beginning to install GPS in their cars. In Oslo, Norway, a taxi company is installing GPS in all its taxis to help track indiviual cars and provide security oversight for its drivers.
Despite its current limitations, cartographic use of GPS is on the increase. Among other purposes, it is being used to verify the location of boundary lines. A private, hand-held GPS unit was recently used to substantiate that the legally defined US-Canadian border is actually 800 metres (2,625 feet) north of its traditional map location between Washington and British Columbia. GPS and related technology will play increasingly important roles in cartographic data collection as the accuracy of satellite-based positioning technology increases.
Geographic Information Systems
|Geographic information systems (GIS) are a means of storing, integrating, analyzing, and presenting geographic data. A typical GIS consists of a combination of computers, databases, and software, with skilled operators who can process and present different thematic data with reference to a single geographic framework.|
Each theme is a layer of data that is linked geographically to other data layers of different themes. A GIS can be used to project combinations of geographical interrelationships of the various data layers onto a single map. Conversely, individual themes can be separated from the overall matrix and considered individually.
GIS can provide insights into complex relationships not easily studied or observed by other means. Instead of dealing with flat paper maps, cartographers use GIS to produce spectacular three-dimensional images for use in advanced applications such as virtual reality.
GIS in Action
|The idea of using map
layers is an old one. It was used, for example, in the 19th century by
Irish railway commissioners. But computers have made the application of
this concept more practical. The Canadian government created and used the
first computerized GIS in the 1960s. Since then, GIS have become a
widespread and highly sophisticated mapping and data analysis tool. GIS
are popular for modelling urban landscapes because they enable city
engineers and planners to view multiple geographical data layers of the
city and track the interaction of these data layers over time.
For example, in Aix-en-Provence, France, city authorities are using GIS to plan new housing for its citizens while maintaining Aix’s historical character. In other situations, city planners can use GIS to determine how average income levels, on a neighbourhood-by-neighbourhood basis, affect the use of public gas, and electric supply lines sharing transmission corridors. Similarly, zoning agencies are beginning to use GIS to analyze complex land-use patterns.
GIS have inspired global approaches to resource management that may help find solutions to major world problems. In one example, in Hungary, the United Nations (UN) is beginning to assemble a system of global soil productivity monitoring that may allow more efficient farming of land for sustained crop yield.
GIS are also extensively incorporated into scientific studies. Ecologists study many different aspects of the earth, often in geographically discrete areas, to learn how various biological and physical factors interact. GIS enables these scientists to separate major factors, including vegetation, hydrology, surface terrain, soil type, and erosion, to study how their interrelationships influence ecosystems.
In Finland, GIS is being used to map and manage forest resources. In Italy, GIS and GPS are being used to map city trees in Bologna’s historical park at Villa Mazzacorti, and an extensive park management system based on these technologies is under development in the Emilia Romagna region.
The US Department of Agriculture (USDA) has been using GIS to monitor the boll weevil control programme in southern Texas since the early 1990s. USDA cartographers digitized—coded as coordinates on a computer map—all farms within an area of several hundred square kilometres. They then used aerial photography to record which farmers in this area tilled the cotton stubble in their fields under the soil after the cotton was harvested. These aerial photographs were digitized and fed into the GIS database. Boll-weevil infestations were then mapped in all the fields for several years and these maps were also entered into the database. With the use of GIS, the USDA was able to prove statistically that the stubble fields that had not been tilled had more weevil infestations. The study supported the hypothesis that stubble provides a winter refuge for the beetles. The GIS also generated intricate practical maps of boll-weevil trouble spots that could be used by the state agricultural agency in controlling the infestations.
|Although GIS are
generally based on sophisticated computer systems, some user-friendly GIS
applications have been developed, too. For example, one company in California
markets a system that enables citrus farmers to monitor fruit production.
This GIS, which can be operated out of the home, receives ground data
collected by the farmer and aerial data fed to this system using satellite
cameras. All these data are fed into a desktop computer so the citrus
grower can monitor the various factors, including fertilization, irrigation,
and tree variety, that are responsible for high versus low fruit
|Remote sensing is the
method of collecting data about an object from a distance. The first
remote-sensing devices were early telescopes used for celestial
observation. With his pioneering telescopic observations of the heavens,
it is likely that Galileo was the first scientist to use remote sensing.
In modern times, remote sensing involves not only the detection of remote objects, for example observing distant stars using powerful radio telescopes, but also automatic detection devices carried by special, remotely operated vehicles.
The special robotic submersible vehicles used to explore the icy depths of the North Atlantic for the wreck of the Titanic are an example of this type of vehicle. Remote detection and remote operation are perhaps most dramatically used in space probes such as NASA’s Mars Explorer space vehicle.
The visual phenomena recorded by remote sensing usually require translation by special sensory devices so the human eye can discern the data. Remote-sensing technology often includes highly sophisticated sensory apparatuses such as cameras fitted with special infrared detectors. For example, Synthetic Aperture Radar (SAR) is used in reconnaissance aircraft and in satellites to detect the spread of oil on the sea after oil spills.
Remote Sensing and Cartography
|Remote sensing has opened
up new realms of geographic information for cartographers. Extensive
vegetation surveys are made from high altitudes to show the distribution
of specific crops, weeds, or native plants amidst an expanse of general
High-resolution satellite cameras located at altitudes of several hundred kilometres can record details as small as a few metres in diameter on the surface of the Earth. Satellites such as those in the LANDSAT series sweep the globe with continuous scans to provide detailed up-to-date maps of nearly the entire Earth. Satellite imagery is also used to create up-to-the-moment weather maps. Increasingly, data obtained from remote sensing are being assembled into complex, highly refined electronic images resembling photographs that are best viewed on colour computer monitors or television screens.
Remote sensing is used to reveal obscure or misunderstood phenomena. An example is the recent detection of the lost city of Ubar in Oman, which was rediscovered with the help of NASA satellite radar imagery. Image analysts used cartographic methods to pick out clues from the radar images, including caravan tracks that pointed them to the buried city ruins.
Most maps and atlases use data from remote-sensing sources to create some of its maps. Remote-sensing sources used in these maps include SPOT satellite images of cities, Earth by Day and Earth at Night composite satellite images, and hypsography, or terrain and elevation data, for the entire world. The Eco-regions data in Encarta World Atlas is a combination of remotely sensed vegetation, land cover, and climate data composed in a GIS setting.