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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 the world is measurable and that we can make reliable representations or models of that reality. Mapmaking involves advanced skills and attitudes, particularly the use of symbols to represent certain geographic phenomena, as well as the ability to visualize the world in an abstract and scaled down form.
History
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 planimetric map is like a topographic one but without elevations: countour lines or spot heights. 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. Map design
Naming conventions There are several ways to name the places on a map. Early explorers named locations after themselves, people in their homeland, religious characters, ruler(s) of their countries, events occurring in the vicinity, physical characteristics, etc. For example, 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 as was Nome, Alaska, according to legend. Map symbolization The quality of a map’s design affects its reader’s ability to extract information, and to learn from the map. Cartographic symbology has been developed in an effort to portray the world accurately and effectively convey information to the map reader. A legend explains the pictorial language of the map known as its symbology. The title indicates the region the map portrays; the map image portrays the region and so on. Although every map element serves some purpose, convention only dictates inclusion of some elements while others are considered optional. A menu of map elements includes the neatline (border), compass rose or north arrow, overview map, scale bar, projection, and information about the map sources, accuracy and publication. When examining a landscape, scale can be intuited from trees, houses and cars. Not so with a map. Even such a simple thing as a north arrow is crucial. It may seem obvious that the top of a map should point north but this might not be the case. Color likewise is equally important. How the cartographer displays the data in different hues can greatly affect the understanding or feel of the map. Different intensities of hue portray different objectives the cartographer is attempting to get across to the audience. Today, personal computers can display up to 16 million distinct colors at a time even though the human eye can distinguish only a minimum number of these (Jeer, 1997). This fact allows for a multitude of color options for even for the most demanding maps. Moreover, computers can easily hatch patterns in colors to give even more options. This is very beneficial when symbolizing data in categories such as quintile and equal interval classifications. Quantitative symbols give a visual measure of the relative size/importance/number that a symbol represents and to symbolize this data on a map there are two major classes of symbols used for portraying quantitative properties: Proportional symbols change their visual weight according to a quantitative property. These are appropriate for extensive statistics. Choropleth maps portray data collection areas (such as counties, or census tracts) with color. Using color this way, the darkness and intensity (or value) of the color is evaluated by the eye as a measure of intensity or concentration (Harvard Graduate School of Design, 2005). See also | ||||||||||||
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