History of cartography
Cartography, or mapmaking, has been an integral part of human history for millions of years. From cave paintings to ancient maps of Babylon and Asia, through the Age of Discovery, on into the 21st century, people have created and used maps as essential tools to help them define and navigate their way through the world. Maps began as two-dimensional drawings but can adopt three-dimensional shapes and be stored in purely numerical forms; the term cartography is modern, loaned into English from French cartographie in the 1840s, based on Middle Latin carta "map". The earliest known maps are of the stars, not the earth. Dots dating to 14,500 BC found on the walls of the Lascaux caves map out part of the night sky, including the three bright stars Vega and Altair, as well as the Pleiades star cluster; the Cuevas de El Castillo in Spain contain a dot map of the Corona Borealis constellation dating from 12,000 BC. Cave painting and rock carvings used simple visual elements that may have aided in recognizing landscape features, such as hills or dwellings.
A map-like representation of a mountain, river and routes around Pavlov in the Czech Republic has been dated to 25,000 BC, a 14,000 BC polished chunk of sandstone from a cave in Spanish Navarre may represent similar features superimposed on animal etchings, although it may represent a spiritual landscape, or simple incisings. Another ancient picture that resembles a map was created in the late 7th millennium BC in Çatalhöyük, modern Turkey; this wall painting may represent a plan of this Neolithic village. Maps in Ancient Babylonia were made by using accurate surveying techniques. For example, a 7.6 × 6.8 cm clay tablet found in 1930 at Ga-Sur, near contemporary Kirkuk, shows a map of a river valley between two hills. Cuneiform inscriptions label the features on the map, including a plot of land described as 354 iku, owned by a person called Azala. Most scholars date the tablet to the 25th to 24th century BC; the map is marked to show the cardinal directions. An engraved map from the Kassite period of Babylonian history shows walls and buildings in the holy city of Nippur.
In contrast, the Babylonian World Map, the earliest surviving map of the world, is a symbolic, not a literal representation. It deliberately omits peoples such as the Persians and Egyptians, who were well known to the Babylonians; the area shown is depicted as a circular shape surrounded by water, which fits the religious image of the world in which the Babylonians believed. Examples of maps from ancient Egypt are quite rare. However, those that have survived show an emphasis on geometry and well-developed surveying techniques stimulated by the need to re-establish the exact boundaries of properties after the annual Nile floods; the Turin Papyrus Map, dated c. 1160 BC, shows the mountains east of the Nile where gold and silver were mined, along with the location of the miners' shelters and the road network that linked the region with the mainland. Its originality can be seen in the map's inscriptions, its precise orientation, the use of color. In reviewing the literature of early geography and early conceptions of the earth, all sources lead to Homer, considered by many as the founding father of Geography.
Regardless of the doubts about Homer's existence, one thing is certain: he never was a mapmaker. The depiction of the Earth conceived by Homer, accepted by the early Greeks, represents a circular flat disk surrounded by a moving stream of Ocean, an idea which would be suggested by the appearance of the horizon as it is seen from a mountaintop or from a seacoast. Homer's knowledge of the Earth was limited, he and his Greek contemporaries knew little of the Earth beyond Egypt as far south as the Libyan desert, the south-west coast of Asia Minor, the northern boundary of the Greek homeland. Furthermore, the coast of the Black Sea was only known through myths and legends that circulated during his time. In his poems there is no mention of Asia as geographical concepts; that is why the big part of Homer's world, portrayed on this interpretive map represents lands that border on the Aegean Sea. It is worth noting that though Greeks believed that they were in the middle of the earth, they thought that the edges of the world's disk were inhabited by savage, monstrous barbarians and strange animals and monsters.
Additional statements about ancient geography may be found in Hesiod's poems written during the 8th century BC. Through the lyrics of Works and Days and Theogony he shows to his contemporaries some definite geographical knowledge, he introduces the names of such rivers as Nile, the shores of the Bosporus, the Euxine, the coast of Gaul, the island of Sicily, a few other regions and rivers. His advanced geographical knowledge not only had predated Greek colonial expansions, but was used in the earliest Greek world maps, produced by Greek mapmakers such as Anaximander and Hecataeus of Miletus, Ptolemy using both observations by explorers and a mathematical approach. Early steps in the development of intellectual thought in ancient Greece belonged to Ionians from their well-known city of Miletus in Asia Minor. Miletus was placed favourably to absorb aspects of Babylonian knowledge and to profit from the expanding commerce of the Mediterranean; the earliest ancient Greek, said to
The Behrmann projection is a cylindrical map projection described by Walter Behrmann in 1910. It is a member of the cylindrical equal-area projection family. Members of the family differ by their standard parallels, which are parallels along which the projection has no distortion. In the case of the Behrmann projection, the standard parallels are 30°N and 30°S; the projection shares many characteristics with other members of the family such as the Lambert cylindrical equal-area projection, whose standard parallel is the equator, the Gall–Peters projection, whose standard parallels are 45°N and 45°S. While equal-area, distortion of shape increases in the Behrmann projection according to distance from the standard parallels; this projection is not equidistant. List of map projections Media related to Maps with Behrmann projection at Wikimedia Commons Table of examples and properties of all common projections, from radicalcartography.net An interactive Java Applet to study the metric deformations of the Berhrmann Projection
The Mercator projection is a cylindrical map projection presented by the Flemish geographer and cartographer Gerardus Mercator in 1569. It became the standard map projection for nautical navigation because of its ability to represent lines of constant course, known as rhumb lines or loxodromes, as straight segments that conserve the angles with the meridians. Although the linear scale is equal in all directions around any point, thus preserving the angles and the shapes of small objects, the Mercator projection distorts the size of objects as the latitude increases from the Equator to the poles, where the scale becomes infinite. So, for example, landmasses such as Greenland and Antarctica appear much larger than they are, relative to landmasses near the equator such as Central Africa. Mercator's 1569 edition was a large planisphere measuring 202 by 124 cm, printed in eighteen separate sheets; as in all cylindrical projections and meridians are straight and perpendicular to each other. In accomplishing this, the unavoidable east-west stretching of the map, which increases as distance away from the equator increases, is accompanied in the Mercator projection by a corresponding north-south stretching, so that at every point location the east-west scale is the same as the north-south scale, making it a conformal map projection.
Conformal projections preserve angles around all locations. Because the linear scale of a Mercator map increases with latitude, it distorts the size of geographical objects far from the equator and conveys a distorted perception of the overall geometry of the planet. At latitudes greater than 70° north or south the Mercator projection is unusable, because the linear scale becomes infinitely large at the poles. A Mercator map can therefore never show the polar areas. All lines of constant bearing are represented by straight segments on a Mercator map; the two properties and straight rhumb lines, make this projection uniquely suited to marine navigation: courses and bearings are measured using wind roses or protractors, the corresponding directions are transferred from point to point, on the map, with the help of a parallel ruler. The name and explanations given by Mercator to his world map show that it was expressly conceived for the use of marine navigation. Although the method of construction is not explained by the author, Mercator used a graphical method, transferring some rhumb lines plotted on a globe to a square graticule, adjusting the spacing between parallels so that those lines became straight, making the same angle with the meridians as in the globe.
The development of the Mercator projection represented a major breakthrough in the nautical cartography of the 16th century. However, it was much ahead of its time, since the old navigational and surveying techniques were not compatible with its use in navigation. Two main problems prevented its immediate application: the impossibility of determining the longitude at sea with adequate accuracy and the fact that magnetic directions, instead of geographical directions, were used in navigation. Only in the middle of the 18th century, after the marine chronometer was invented and the spatial distribution of magnetic declination was known, could the Mercator projection be adopted by navigators. Several authors are associated with the development of Mercator projection: German Erhard Etzlaub, who had engraved miniature "compass maps" of Europe and parts of Africa, latitudes 67°–0°, to allow adjustment of his portable pocket-size sundials, was for decades declared to have designed "a projection identical to Mercator's".
Portuguese mathematician and cosmographer Pedro Nunes, who first described the loxodrome and its use in marine navigation, suggested the construction of a nautical atlas composed of several large-scale sheets in the cylindrical equidistant projection as a way to minimize distortion of directions. If these sheets were brought to the same scale and assembled an approximation of the Mercator projection would be obtained. English mathematician Edward Wright. English mathematicians Thomas Harriot and Henry Bond who, associated the Mercator projection with its modern logarithmic formula deduced by calculus; as on all map projections, shapes or sizes are distortions of the true layout of the Earth's surface. The Mercator projection exaggerates areas far from the equator. For example: Greenland appears larger than Africa, when in reality Africa's area is 14 times greater and Greenland's is comparable to Algeria's alone. Africa appears to be the same size as Europe, when in reality Africa is nearly 3 times larger.
Alaska takes as much area on the map as Brazil, when Brazil's area is nearly five times that of Alaska. Finland appears with a greater north-south extent than India. Antarctica appears as the biggest continent, although it is the fifth in area; the Mercator projection is still used for navigation. On the other hand, because of great land area distortions, it is not well suited for general world maps. Therefore, Mercator himsel
A map projection is a systematic transformation of the latitudes and longitudes of locations from the surface of a sphere or an ellipsoid into locations on a plane. Maps cannot be created without map projections. All map projections distort the surface in some fashion. Depending on the purpose of the map, some distortions are acceptable and others are not. There is no limit to the number of possible map projections. More the surfaces of planetary bodies can be mapped if they are too irregular to be modeled well with a sphere or ellipsoid. More projections are a subject of several pure mathematical fields, including differential geometry, projective geometry, manifolds. However, "map projection" refers to a cartographic projection. Maps can be more useful than globes in many situations: they are more compact and easier to store; these useful traits of maps motivate the development of map projections. However, Carl Friedrich Gauss's Theorema Egregium proved that a sphere's surface cannot be represented on a plane without distortion.
The same applies to other reference surfaces used as models for the Earth, such as oblate spheroids and geoids. Since any map projection is a representation of one of those surfaces on a plane, all map projections distort; every distinct map projection distorts in a distinct way. The study of map projections is the characterization of these distortions. Projection is not limited to perspective projections, such as those resulting from casting a shadow on a screen, or the rectilinear image produced by a pinhole camera on a flat film plate. Rather, any mathematical function transforming coordinates from the curved surface to the plane is a projection. Few projections in actual use are perspective. For simplicity, most of this article assumes. In reality, the Earth and other large celestial bodies are better modeled as oblate spheroids, whereas small objects such as asteroids have irregular shapes. Io is better modeled by triaxial prolated spheroid with small eccentricities. Haumea's shape is a Jacobi ellipsoid, with its major axis twice as long as its minor and with its middle axis one and half times as long as its minor.
These other surfaces can be mapped as well. Therefore, more a map projection is any method of "flattening" a continuous curved surface onto a plane. Many properties can be measured on the Earth's surface independent of its geography; some of these properties are: Area Shape Direction Bearing Distance ScaleMap projections can be constructed to preserve at least one of these properties, though only in a limited way for most. Each projection compromises, or approximates basic metric properties in different ways; the purpose of the map determines. Because many purposes exist for maps, a diversity of projections have been created to suit those purposes. Another consideration in the configuration of a projection is its compatibility with data sets to be used on the map. Data sets are geographic information. Different datums assign different coordinates to the same location, so in large scale maps, such as those from national mapping systems, it is important to match the datum to the projection; the slight differences in coordinate assignation between different datums is not a concern for world maps or other vast territories, where such differences get shrunk to imperceptibility.
The classical way of showing the distortion inherent in a projection is to use Tissot's indicatrix. For a given point, using the scale factor h along the meridian, the scale factor k along the parallel, the angle θ′ between them, Nicolas Tissot described how to construct an ellipse that characterizes the amount and orientation of the components of distortion. By spacing the ellipses along the meridians and parallels, the network of indicatrices shows how distortion varies across the map; the creation of a map projection involves two steps: Selection of a model for the shape of the Earth or planetary body. Because the Earth's actual shape is irregular, information is lost in this step. Transformation of geographic coordinates to Cartesian or polar plane coordinates. In large-scale maps, Cartesian coordinates have a simple relation to eastings and northings defined as a grid superimposed on the projection. In small-scale maps and northings are not meaningful, grids are not superimposed; some of the simplest map projections are literal projections, as obtained by placing a light source at some definite point relative to the globe and projecting its features onto a specified surface.
This is not the case for most projections, which are defined only in terms of mathematical formulae that have no direct geometric interpretation. However, picturing the light source-globe model can be helpful in understanding the basic concept of a map projection A surface that can be unfolded or unrolled into a plane or sheet without stretching, tearing or shrinking is called a developable surface; the cylinder and the plane are all developable surfaces. The sphere and ellipsoid do not have developable surfaces, so any projection of them onto a plane will have to dis
Lambert cylindrical equal-area projection
In cartography, the Lambert cylindrical equal-area projection, or Lambert cylindrical projection, is a cylindrical equal-area projection. This projection is undistorted along the equator, its standard parallel, but distortion increases towards the poles. Like any cylindrical projection, it stretches parallels away from the equator; the poles accrue infinite distortion. The projection was invented by the Swiss mathematician Johann Heinrich Lambert and described in his 1772 treatise, Beiträge zum Gebrauche der Mathematik und deren Anwendung, part III, section 6: Anmerkungen und Zusätze zur Entwerfung der Land- und Himmelscharten, translated as, Notes and Comments on the Composition of Terrestrial and Celestial Maps. Lambert's projection is the basis for the cylindrical equal-area projection family. Lambert chose the equator as the parallel of no distortion. By multiplying the projection's height by some factor and dividing the width by the same factor, the regions of no distortion can be moved to any desired pair of parallels north and south of the equator.
These variations the Gall–Peters projection, are more encountered in maps than Lambert’s original projection due to their lower distortion overall. X = λ − λ 0 y = sin φ where φ is the latitude, λ is the longitude and λ0 is the central meridian. List of map projections Lambert azimuthal equal-area projection Lambert conformal conic projection Media related to Lambert cylindrical equal-area projection at Wikimedia Commons Table of examples and properties of all common projections, from radicalcartography.net An interactive Java Applet to study the metric deformations of the Lambert Cylindrical Equal-Area Projection
National Oceanic and Atmospheric Administration
The National Oceanic and Atmospheric Administration is an American scientific agency within the United States Department of Commerce that focuses on the conditions of the oceans, major waterways, the atmosphere. NOAA warns of dangerous weather, charts seas, guides the use and protection of ocean and coastal resources, conducts research to provide understanding and improve stewardship of the environment. NOAA was formed in 1970 and in 2017 had over 11,000 civilian employees, its research and operations are further supported by 321 uniformed service members who make up the NOAA Commissioned Corps. Since October 2017, NOAA has been headed by Timothy Gallaudet, as acting Under Secretary of Commerce for Oceans and Atmosphere and NOAA interim administrator. NOAA plays several specific roles in society, the benefits of which extend beyond the US economy and into the larger global community: A Supplier of Environmental Information Products. NOAA supplies to its customers and partners information pertaining to the state of the oceans and the atmosphere.
This is clear through the production of weather warnings and forecasts via the National Weather Service, but NOAA's information products extend to climate and commerce as well. A Provider of Environmental Stewardship Services. NOAA is a steward of U. S. coastal and marine environments. In coordination with federal, local and international authorities, NOAA manages the use of these environments, regulating fisheries and marine sanctuaries as well as protecting threatened and endangered marine species. A Leader in Applied Scientific Research. NOAA is intended to be a source of accurate and objective scientific information in the four particular areas of national and global importance identified above: ecosystems, climate and water, commerce and transportation; the five "fundamental activities" are: Monitoring and observing Earth systems with instruments and data collection networks. Understanding and describing Earth systems through research and analysis of that data. Assessing and predicting the changes of these systems over time.
Engaging and informing the public and partner organizations with important information. Managing resources for the betterment of society and environment. NOAA traces its history back to multiple agencies, some of which were among the oldest in the federal government: United States Coast and Geodetic Survey, formed in 1807 Weather Bureau of the United States, formed in 1870 Bureau of Commercial Fisheries, formed in 1871 Coast and Geodetic Survey Corps, formed in 1917Another direct predecessor of NOAA was the Environmental Science Services Administration, into which several existing scientific agencies such as the United States Coast and Geodetic Survey, the Weather Bureau and the uniformed Corps were absorbed in 1965. NOAA was established within the Department of Commerce via the Reorganization Plan No. 4 and formed on October 3, 1970 after U. S. President Richard Nixon proposed creating a new agency to serve a national need for "better protection of life and property from natural hazards …for a better understanding of the total environment… for exploration and development leading to the intelligent use of our marine resources."
In 2007, NOAA celebrated 200 years of service in its role as successor to the United States Survey of the Coast. In 2013, NOAA closed 600 weather stations. Since October 25, 2017 Timothy Gallaudet, Assistant Secretary of Commerce for Oceans and Atmosphere, has served as acting Under Secretary of Commerce for Oceans and Atmosphere at the US Department of Commerce and NOAA's interim administrator. Gallaudet succeeded Benjamin Friedman, who served as NOAA's interim administrator since the end of the Obama Administration on January 20, 2017. In October 2017, Barry Lee Myers, CEO of AccuWeather, was proposed to be the agency's administrator by the Trump Administration. NOAA works toward its mission through six major line offices, the National Environmental Satellite and Information Service, the National Marine Fisheries Service, the National Ocean Service, the National Weather Service, the Office of Oceanic and Atmospheric Research and the Office of Marine & Aviation Operations, and in addition more than a dozen staff offices, including the Office of the Federal Coordinator for Meteorology, the NOAA Central Library, the Office of Program Planning and Integration.
The National Weather Service is tasked with providing "weather and climate forecasts and warnings for the United States, its territories, adjacent waters and ocean areas, for the protection of life and property and the enhancement of the national economy." This is done through a collection of national and regional centers, 13 river forecast centers, more than 120 local weather forecast offices. They are charged with issuing weather and river forecasts, advisories and warnings on a daily basis, they issue more than 734,000 weather and 850,000 river forecasts, more than 45,000 severe weather warnings annually. NOAA data is relevant to the issues of global warming and ozone depletion; the NWS operates NEXRAD, a nationwide network of Doppler weather radars which can detect precipitation and their velocities. Many of their products are broadcast on NOAA Weather Radio, a network of radio transmitters that broadcasts weather forecasts, severe weather statements and warnings 24 hours a day; the National Ocean Service focuses on ensuring that ocean and coastal areas are safe and productive.
NOS scientists, natural resource managers, specialists serve America by ensuring safe and efficient marine transportation, promoting innovative solutions to protect coastal communities, conserving mari
A geodetic datum or geodetic system is a coordinate system, a set of reference points, used to locate places on the Earth. An approximate definition of sea level is the datum WGS 84, an ellipsoid, whereas a more accurate definition is Earth Gravitational Model 2008, using at least 2,159 spherical harmonics. Other datums are defined at other times. Mars has no oceans and so no sea level, but at least two martian datums have been used to locate places there. Datums are used in geodesy and surveying by cartographers and satellite navigation systems to translate positions indicated on maps to their real position on Earth; each starts with an ellipsoid, defines latitude and altitude coordinates. One or more locations on the Earth's surface are chosen as anchor "base-points"; the difference in co-ordinates between datums is referred to as datum shift. The datum shift between two particular datums can vary from one place to another within one country or region, can be anything from zero to hundreds of meters.
The North Pole, South Pole and Equator will be in different positions on different datums, so True North will be different. Different datums use different interpolations for the precise size of the Earth; because the Earth is an imperfect ellipsoid, localised datums can give a more accurate representation of the area of coverage than WGS 84. OSGB36, for example, is a better approximation to the geoid covering the British Isles than the global WGS 84 ellipsoid. However, as the benefits of a global system outweigh the greater accuracy, the global WGS 84 datum is becoming adopted. Horizontal datums are used for describing a point on the Earth's surface, in latitude and longitude or another coordinate system. Vertical datums measure depths. In surveying and geodesy, a datum is a reference system or an approximation of the Earth's surface against which positional measurements are made for computing locations. Horizontal datums are used for describing a point on the Earth's surface, in latitude and longitude or another coordinate system.
Vertical datums are used to underwater depths. The horizontal datum is the model used to measure positions on the Earth. A specific point on the Earth can have different coordinates, depending on the datum used to make the measurement. There are hundreds of local horizontal datums around the world referenced to some convenient local reference point. Contemporary datums, based on accurate measurements of the shape of the Earth, are intended to cover larger areas; the WGS 84 datum, identical to the NAD83 datum used in North America and the ETRS89 datum used in Europe, is a common standard datum. For example, in Sydney there is a 200 metres difference between GPS coordinates configured in GDA and AGD, an unacceptably large error for some applications, such as surveying or site location for scuba diving. A vertical datum is a reference surface for vertical positions, such as the elevations of Earth features including terrain, water level, man-made structures. In geodetic coordinates, the Earth's surface is approximated by an ellipsoid, locations near the surface are described in terms of latitude and height.
Geodetic latitude, resp. altitude, is different from geocentric latitude, resp. altitude. Geodetic latitude is determined by the angle between the equatorial plane and normal to the ellipsoid, whereas geocentric latitude is determined by the angle between the equatorial plane and line joining the point to the centre of the ellipsoid. Unless otherwise specified, latitude is geodetic latitude; the ellipsoid is parameterised by the semi-major axis a and the flattening f. From a and f it is possible to derive the semi-minor axis b, first eccentricity e and second eccentricity e ′ of the ellipsoid The two main reference ellipsoids used worldwide are the GRS80 and the WGS84. A more comprehensive list of geodetic systems can be found here; the Global Positioning System uses the World Geodetic System 1984 to determine the location of a point near the surface of the Earth. Datum conversion is the process of converting the coordinates of a point from one datum system to another. Datum conversion may be accompanied by a change of grid projection.
A geodetic reference datum is a known and constant surface, used to describe the location of unknown points on the Earth. Since reference datums can have different radii and different center points, a specific point on the Earth can have different coordinates depending on the datum used to make the measurement. There are hundreds of locally developed reference datums around the world referenced to some convenient local reference point. Contemporary datums, based on accurate measurements of the shape of the Earth, are intended to cover larger areas; the mos