Cartography

Jai Ganesh · 2025-08-15 19:17:30

Cartography

Gist

The English term cartography is modern, borrowed from the French cartographie in the 1840s, itself based on Middle Latin carta "map".

The Oxford Dictionary of English app defines a cartographer as “a person who draws or produces maps.” Merriam-Webster's online dictionary says a cartographer is “one that makes maps.” And the Cambridge Dictionary, also available online, states that a cartographer is “someone who makes or draws maps.”

Summary

Cartography is the art and science of graphically representing a geographical area, usually on a flat surface such as a map or chart. It may involve the superimposition of political, cultural, or other nongeographical divisions onto the representation of a geographical area.

Cartography is an ancient discipline that dates from the prehistoric depiction of hunting and fishing territories. The Babylonians mapped the world in a flattened, disk-shaped form, but Claudius Ptolemaeus (Ptolemy) established the basis for subsequent efforts in the 2nd century ce with his eight-volume work Geōgraphikē hyphēgēsis (Guide to Geography) that showed a spherical Earth. Maps produced during the Middle Ages followed Ptolemy’s guide, but they used Jerusalem as the central feature and placed East at the top. Those representations are often called T-maps because they show only three continents (Europe, Asia, and Africa), separated by the “T” formed by the Mediterranean Sea and the Nile River. More accurate geographical representation began in the 14th century when portolan (seamen’s) charts were compiled for navigation.

The discovery of the New World by Europeans led to the need for new techniques in cartography, particularly for the systematic representation on a flat surface of the features of a curved surface—generally referred to as a projection (e.g., Mercator projection, cylindrical projection, and Lambert conformal projection). During the 17th and 18th centuries there was a vast outpouring of printed maps of ever-increasing accuracy and sophistication. Systematic surveys were undertaken involving triangulation that greatly improved map reliability and precision. Noteworthy among the scientific methods introduced later was the use of the telescope for determining the length of a degree of longitude.

Modern cartography largely involves the use of aerial and, increasingly, satellite photographs as a base for any desired map or chart. The procedures for translating photographic data into maps are governed by the principles of photogrammetry and yield a degree of accuracy previously unattainable. The remarkable improvements in satellite photography since the late 20th century and the general availability on the Internet of satellite images have made possible the creation of Google Earth and other databases that are widely available online. Satellite photography has also been used to create highly detailed maps of features of the Moon and of several planets in our solar system and their satellites. In addition, the use of geographic information systems (GIS) has been indispensible in expanding the scope of cartographic subjects.

Details

Cartography (/kɑːrˈtɒɡrəfi/)[a] is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an imagined reality) can be modeled in ways that communicate spatial information effectively.

The fundamental objectives of traditional cartography are to:

* Set the map's agenda and select traits of the object to be mapped. This is the concern of map editing. Traits may be physical, such as roads or land masses, or may be abstract, such as toponyms or political boundaries.
* Represent the terrain of the mapped object on flat media. This is the concern of map projections.
* Eliminate the mapped object's characteristics that are irrelevant to the map's purpose. This is the concern of generalization.
* Reduce the complexity of the characteristics that will be mapped. This is also the concern of generalization.
* Orchestrate the elements of the map to best convey its message to its audience. This is the concern of map design.
* Modern cartography constitutes many theoretical and practical foundations of geographic information systems (GIS) and geographic information science (GISc).

Modern Period

In cartography, technology has continually changed in order to meet the demands of new generations of mapmakers and map users. The first maps were produced manually, with brushes and parchment; so they varied in quality and were limited in distribution. The advent of magnetic devices, such as the compass and much later, magnetic storage devices, allowed for the creation of far more accurate maps and the ability to store and manipulate them digitally.

Advances in mechanical devices such as the printing press, quadrant, and vernier allowed the mass production of maps and the creation of accurate reproductions from more accurate data. Hartmann Schedel was one of the first cartographers to use the printing press to make maps more widely available. Optical technology, such as the telescope, sextant, and other devices that use telescopes, allowed accurate land surveys and allowed mapmakers and navigators to find their latitude by measuring angles to the North Star at night or the Sun at noon.

Advances in photochemical technology, such as the lithographic and photochemical processes, make possible maps with fine details, which do not distort in shape and which resist moisture and wear. This also eliminated the need for engraving, which further speeded up map production.

In the 20th century, aerial photography, satellite imagery, and remote sensing provided efficient, precise methods for mapping physical features, such as coastlines, roads, buildings, watersheds, and topography. The United States Geological Survey has devised multiple new map projections, notably the Space Oblique Mercator for interpreting satellite ground tracks for mapping the surface. The use of satellites and space telescopes now allows researchers to map other planets and moons in outer space. Advances in electronic technology ushered in another revolution in cartography: ready availability of computers and peripherals such as monitors, plotters, printers, scanners (remote and document) and analytic stereo plotters, along with computer programs for visualization, image processing, spatial analysis, and database management, have democratized and greatly expanded the making of maps. The ability to superimpose spatially located variables onto existing maps has created new uses for maps and new industries to explore and exploit these potentials. See also digital raster graphic.

In the early years of the new millennium, three key technological advances transformed cartography: the removal of Selective Availability in the Global Positioning System (GPS) in May 2000, which improved locational accuracy for consumer-grade GPS receivers to within a few metres; the invention of OpenStreetMap in 2004, a global digital counter-map that allowed anyone to contribute and use new spatial data without complex licensing agreements; and the launch of Google Earth in 2005 as a development of the virtual globe EarthViewer 3D (2004), which revolutionised accessibility of accurate world maps, as well as access to satellite and aerial imagery. These advances brought more accuracy to geographical and location-based data and widened the range of applications for cartography, for example in the development of satnav devices.

Today most commercial-quality maps are made using software of three main types: CAD, GIS and specialized illustration software. Spatial information can be stored in a database, from which it can be extracted on demand. These tools lead to increasingly dynamic, interactive maps that can be manipulated digitally.

On the other hand, we can observe a reverse trend. In contemporary times, there is a resurgence of interest in the most beautiful periods of cartography, with various maps being created using, for example, Renaissance-style aesthetics. We encounter imitators or continuators of Renaissance traditions that merge the realms of science and art. Among them are figures such as Luther Phillips (1891–1960) and Ruth Rhoads Lepper Gardner (1905–2011), who still operated using traditional cartographic methods, as well as creators utilizing modern developments based on GIS solutions and those employing techniques that combine advanced GIS/CAD methods with traditional artistic forms.

Field-rugged computers, GPS, and laser rangefinders make it possible to create maps directly from measurements made on site.

Additional Information

Physical Map

A physical map usually includes labels for features such as mountain ranges and bodies of water. In this map of North America, the shape and contours of the seafloor, such as basins and the Mid-Atlantic Ridge, are clearly identified.

Maps

A map is a symbolic representation of selected characteristics of a place, usually drawn on a flat surface. Maps present information about the world in a simple, visual way. They teach about the world by showing sizes and shapes of countries, locations of features, and distances between places. Maps can show distributions of things over Earth, such as settlement patterns. They can show exact locations of houses and streets in a city neighborhood.

Mapmakers, called cartographers, create maps for many different purposes. Vacationers use road maps to plot routes for their trips. Meteorologists—scientists who study weather—use weather maps to prepare forecasts. City planners decide where to put hospitals and parks with the help of maps that show land features and how the land is currently being used.

Some common features of maps include scale, symbols and grids.

Scale

All maps are scale models of reality. A map’s scale indicates the relationship between the distances on the map and the actual distances on Earth. This relationship can be expressed by a graphic scale, a verbal scale, or a representative fraction.

The most common type of graphic scale looks like a ruler. Also called a bar scale, it is simply a horizontal line marked off in miles, kilometers, or some other unit measuring distance.

The verbal scale is a sentence that relates distance on the map to distance on Earth. For example, a verbal scale might say, “one centimeter represents one kilometer” or “one inch represents eight miles.”

The representative fraction does not have specific units. It is shown as a fraction or ratio—for example, 1/1,000,000 or 1:1,000,000. This means that any given unit of measure on the map is equal to one million of that unit on Earth. So, 1 centimeter on the map represents 1,000,000 centimeters on Earth, or 10 kilometers. One inch on the map represents 1,000,000 inches on Earth, or a little less than 16 miles.

The size of the area covered helps determine the scale of a map. A map that shows an area in great detail, such as a street map of a neighborhood, is called a large-scale map because objects on the map are relatively large. A map of a larger area, such as a continent or the world, is called a small-scale map because objects on the map are relatively small.

Today, maps are often computerized. Many computerized maps allow the viewer to zoom in and out, changing the scale of the map. A person may begin by looking at the map of an entire city that only shows major roads and then zoom in so that every street in a neighborhood is visible.

Symbols

Cartographers use symbols to represent geographic features. For example, black dots represent cities, circled stars represent capital cities, and different sorts of lines represent boundaries, roads, highways and rivers. Colors are often used as symbols. Green is often used for forests, tan for deserts, and blue for water. A map usually has a legend, or key, that gives the scale of the map and explains what the various symbols represent.

Some maps show relief, or changes in elevation. A common way to show relief is contour lines, also called topographic lines. These are lines that connect points that have equal elevation. If a map shows a large enough area, contour lines form circles.

A group of contour line circles inside one another indicates a change in elevation. As elevation increases, these contour line circles indicate a hill. As elevation decreases, contour line circles indicate a depression in the earth, such as a basin.

Grids

Many maps include a grid pattern, or a series of crossing lines that create squares or rectangles. The grid helps people locate places on the map. On small-scale maps, the grid is often made up of latitude and longitude lines. Latitude lines run east-west around the globe, parallel to the Equator, an imaginary line that circles the middle of Earth. Longitude lines run north-south, from pole to pole. Latitude and longitude lines are numbered. The intersection of latitude and longitude lines, called coordinates, identify the exact location of a place.

On maps showing greater detail, the grid is often given numbers and letters. The boxes made by the grid may be called A, B, C, and so on across the top of the map, and 1, 2, 3, and so on across the left side. In the map’s index, a park’s location might be given as B4. The user finds the park by looking in the box where column B and row 4 cross.

Title, date, author and sources usually appear on the map though not always together. The map’s title tells what the map is about, revealing the map’s purpose and content. For example, a map might be titled “Political Map of the World” or “Battle of Gettysburg, 1863.”

“Date” refers to either the time the map was made or the date relevant to the information on the map. A map of areas threatened by a wildfire, for instance, would have a date, and perhaps even a time, to track the progress of the wildfire. A historical map of the ancient Sumerian Empire would have a date range of between 5,000 B.C. and 1,000 B.C.

Noting a map’s author is important because the cartographer’s perspective will be reflected in the content. Assessing accuracy and objectivity also requires checking sources. A map’s sources are where the author of the map got his or her information. A map of a school district may list the U.S. Census Bureau, global positioning system (GPS) technology, and the school district’s own records as its sources.

Orientation refers to the presence of a compass rose or simply an arrow indicating directions on the map. If only an arrow is used, the arrow usually points north.

A map’s index helps viewers find a specific spot on the map using the grid. A map’s legend explains what the symbols on a map mean.

Map Projections

Transferring information from the spherical, or ball-shaped, surface of Earth onto a flat piece of paper is called projection. A globe, a spherical model of Earth, accurately represents the shapes and locations of the continents. But if a globe were cut in half and each half were flattened out into a map, the result would be wrinkled and torn. The size, shape and relative location of land masses would change.

Projection is a major challenge for cartographers. Every map has some sort of distortion. The larger the area covered by a map, the greater the distortion. Features such as size, shape, distance or scale can be measured accurately on Earth, but once projected on a flat surface only some, not all, of these qualities can be accurately represented. For example, a map can retain either the correct sizes of landmasses or the correct shapes of very small areas, but not both.

Depending on the map’s purpose, cartographers must decide what elements of accuracy are most important to preserve. This determines which projection to use. For example, conformal maps show true shapes of small areas but distort size. Equal area maps distort shape and direction but show true relative sizes of all areas. There are three basic kinds of projections: planar, conical and cylindrical. Each is useful in different situations.

In a planar projection, Earth’s surface is projected onto a plane, or flat surface. Imagine touching a globe with a piece of cardboard, mapping that point of contact, then projecting the rest of map onto the cardboard around that point. Planar projections are most accurate at their centers, where the plane “touches” the globe. They are often used for maps of one of the poles.

Imagine you wrapped a cone around Earth, putting the point of the cone over one of the poles. That is a conical projection. The cone intersects the globe along one or two lines of latitude. When the cone is unwrapped and made into a flat map, latitude lines appear curved in circles or semicircles. Lines of longitude are straight and come together at one pole. In conical projection, areas in the mid-latitudes—regions that are neither close to the Equator nor close to the poles—are represented fairly accurately. For this reason, conical projections are often used for maps of the United States, most of which lies in the mid-latitudes.

For a cylindrical projection, imagine that Earth’s surface is projected onto a tube that is wrapped around the globe. The cylinder touches Earth along one line, most often the Equator. When the cylinder is cut open and flattened into a map, the regions near the Equator are the most accurate. Regions near the poles are the most distorted.

Surveying and Remote Sensing

Cartographers rely on survey data for accurate information about the planet. Surveying is the science of determining the exact size, shape and location of a piece of land. Surveyors gather information from regions both above sea level and beneath bodies of water.

Surveying can be done on foot. Surveyors use many instruments to measure the features, or topography, of the land. A compass, measuring device, and theodolites are often used by surveyors doing field work. A theodolite is an instrument that measures angles. A surveyor may calculate the angle of hills, valleys and other features by using a theodolite, which is usually mounted on a tripod, or three-legged platform.

Today, many surveyors use remote sensing to collect data about an area without actually physically touching it. Sensors that detect light or radiation emitted by objects are mounted to airplanes or space satellites, collecting information about places on Earth from above. One method of remote sensing is aerial photography, taking photographs of Earth from the air. Aerial photography has eliminated much of the legwork for surveyors and has allowed precise surveying of some places that are impossible to reach on foot. Satellites, spacecraft that orbit Earth, perform remote sensing. For example, Landsat, a satellite that circles Earth 14 times a day, transmits huge volumes of data to computers on Earth. The data can be used to quickly make or correct maps.

How Maps Are Made

Before making a map, cartographers decide what area they want to display and what type of information they want to present. They consider the needs of their audience and the purpose of the map. These decisions determine what kind of projection and scale they need, and what sorts of details will be included.

The language of the map is one thing a cartographer must consider. A blind reader needs a map that has information in braille, for instance. The audience for a map can determine how widely a map is used. A map might use red and green symbols to show the location of maple and pine trees. This information might be easily displayed in a simple legend. However, such a map could not be used by people who are color-blind.

Lines of latitude and longitude are mathematically plotted on a flat surface. Features are drawn in their appropriate location.

Before the development of advanced computer and printing techniques, maps were drawn by hand. Cartographers would draw, or scribe, the map on a sheet of coated plastic with a special etching tool, scraping away the colored coating to leave clear, sharp lines. Several different sheets of plastic were layered on top of each other to add shading and place names. The plastic sheets were used to make a metal printing plate, or proof, for publishing the map.

Today, most mapping is done with the help of computers. The coordinates of every point are entered into a computer. By feeding new data into the computer or deleting old data, map changes can be made quickly and easily. Colors can be changed, new roads added, and topographic features, such as the flow of a river, altered. The new map can then be printed out easily.

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Cartography

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