Cartography

Cartography or mapmaking (in Greek chartis = map and graphein = write) is the study and practice of making maps or globes. Maps have traditionally been made using pen and paper, but the advent and spread of computers has revolutionized cartography. Most commercial quality maps are now made with map making software that falls into one of three main types; CAD, GIS, and specialized map illustration software.

Maps function as visualization tools for spatial data. Spatial data is acquired from measurement and can be stored in a database, from which it can be extracted for a variety of purposes. Current trends in this field are moving away from analog methods of mapmaking and toward the creation of increasingly dynamic, interactive maps that can be manipulated digitally. The cartographic process rests on the premise that there is an objective reality and that we can make reliable representations of that reality by adding levels of abstraction.

Contents

1 History 1.1 Technological changes 2 Map types 3 Naming conventions 4 See also

History

The oldest known map dates from the 5th millennium BCE. The oldest maps emphasized topological relationships such as connectedness, adjacency, and containment.

A major development in mapmaking occurred with the advent of geometry, which was first used in Babylonia around the 23rd century BCE. An engraved map of the holy city of Nippur, from the Kassite period (14th – 12th centuries BCE) of Babylonian history, was found at Nippur [1] (http://www-oi.uchicago.edu/OI/PROJ/NIP/PUB93/NSC/NSCFIG7.html). The Egyptians later used geometry to survey land and to resurvey it after the periodic flooding of the Nile obscured the property borders.

The ancient Greeks added a great deal to the art and science of cartography. Strabo (c. 63 BCE – c. 21 CE) is credited as the father of geography because he wrote Geographia, in which he documented and criticized the works of others (most of whom would not be known today had Strabo not mentioned them). Thales of Miletus (c. 600 BCE) thought that the earth was a disk supported by water. Anaximander of Miletus theorized at about the same time that the earth was cylindrical. In 288 BCE, Aristarchus of Samos was the first to say that the sun was the center of universe (see heliocentric theory). In approximately 250 BCE, Eratosthenes of Cyrene estimated the circumference of the earth to within 15 per cent of the modern-day accepted value.

Pythagoras of Ionia, who was the founder of a mathematical cult that developed many number-based superstitions that later became the basis of mathematics, was the first notable person to say that the earth was a sphere. Aristotle later provided arguments in support of this idea. Those arguments can be summarized as follows:

• The lunar eclipse is always circular.
• Ships seem to sink as they move away from view and pass the horizon.
• Some stars can only be seen from certain parts of the earth.

The Greeks also developed the science of map projections, which are methods of representing the curved surface of the earth on a plane. Eratosthenes, Anaximander, and Hipparchus are credited with developing a grid system of longitude and latitude, and Eratosthenes seems to have developed the equirectangular map projection around 200 BCE. Claudius Ptolemy developed map projections as well, including the equidistant conic, around 150 BCE.

European scientific cartography slept through the Middle Ages, when philosophical thought turned toward religion. Though the field advanced in some ways, such as Roger Bacon's investigations of map projections and the appearance of portolano and then portolan charts for plying the European trade routes, there was little impetus for systematic study or application of cartography. Most world 'maps' of the period were Christian cosmological diagrams not intended as rigorous geographical representations. Typically rectangular or circular, they followed the style of the so-called "T and O map," which represents the earth's single land mass as disk-shaped and surrounded by ocean. Large-scale mapping tended toward diagrammatic as well, since cadastral needs generally were met by descriptions of landmarks rather than by measurements. In contrast, the Chinese during this time were using a rectangular coordinate system suitable for real, if rough, surveying. The Chinese did not produce world maps because their cosmology supplied no dogma describing distant lands outside their experience. Writings suggest that Chinese philosophers believed the earth to be flat. With the exception of a few theologians of minority opinion, notably Lactantius, Christian and Islamic philosophers adhered to the Greek conception of a spherical earth.

The discovery of the Americas by Europeans and the subsequent effort to control and divide those lands necessitated the invention of scientific mapping methods. The trend of globalism that was started with the Age of Exploration would continue during the Renaissance. This would, in turn, eventually lead to the Enlightenment a concern for scientific accuracy and a desire to classify the world would further develop scientific mapmaking.

Technological changes

In cartography, technology has continually changed in order to meet the demands of new generations of mapmakers and map users. The first maps were manually constructed with brushes and parchment and therefore 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 for the mass production of maps and the ability to make accurate reproductions from more accurate data. Optical technology, such as the telescope, sextant and other devices that use telescopes, allowed for accurate surveying of land and the ability of 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, have allowed for the creation of maps that have fine details, do not distort in shape and resist moisture and wear. This also eliminated the need for engraving which further shortened the time it takes to make and reproduce maps.

In the mid to late 20th century advances in electronic technology have led to a new revolution in cartography. Specifically computer hardware devices such as computer screens, plotters, printers, scanners (remote and document) and analytic stereo plotters along with visualization, image processing, spatial analysis and database software, have democratized and greatly expanded the making of maps. See also digital raster graphic.

Map types

In understanding basic maps, the field of cartography can be divided into two general categories: general cartography and thematic cartography. General cartography involves those maps that are constructed for a general audience and thus contain a variety of features. General maps exhibit many reference and location systems and often are produced in a series. For example the 1:24,000 scale topographic maps of the United States Geological Survey (USGS) are a standard as compared to the 1:50,000 scale Canadian maps.

A topographic map is primarily concerned with the topography of a place, and is typically different from other maps by its use of contour lines showing elevation.

A topological map is a very general type of map, the kind you might sketch on a napkin.

Thematic cartography involves maps of specific geographic themes oriented toward specific audiences. A couple of examples might be a dot map showing corn production in Indiana or a shaded area map of Ohio counties divided into numerical choropleth classes. As the volume of geographic data has exploded over the last century, thematic cartography has become increasingly useful and necessary to interpret spatial cultural and social data.

Two of the most influential American cartographers, especially in thematic cartography have been Arthur H. Robinson at the University of Wisconsin-Madison and George F. Jenks at the University of Kansas.

Naming conventions

There are several ways to name the places on a map. Early explorers named them in several ways — after themselves, people in their homeland, and the ruler(s) of their countries. Features were also named by appearance, local climate, incidents that happened in the vicinity, and location. Many places along the coast of Brazil were named by Portuguese explorers in the early 1500s after the saint of the day of discovery in the Catholic calendar of saints (so that the detailed timetable of their expeditions can often be recovered from the list of assigned names).

Cartographers also borrowed native names, sometimes by transliterating the written form into the Latin alphabet, but most often by transcribing the sound, or attempting to do so. Often the explorer would address the nearest native, pointing at the landmark in question and speaking in a loud voice; whatever the native said was then written down as its name. The Yucatan Peninsula was named in this way.

See also

• List of cartographers
• Sea level
• Geocode
• Geographic Information System (GIS)
• Cartogram
• Animated mapping
• Map design
• Figure-Ground in Map Design
• The article titled great circle distance explains how to find that quantity if one knows the two latitudes and longitudes.