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106-593: The World Geodetic System ( WGS ) is a standard used in cartography , geodesy , and satellite navigation including GPS . The current version, WGS 84 , defines an Earth-centered, Earth-fixed coordinate system and a geodetic datum , and also describes the associated Earth Gravitational Model (EGM) and World Magnetic Model (WMM). The standard is published and maintained by the United States National Geospatial-Intelligence Agency . Efforts to supplement

212-596: 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. A third type of map is known as an "orienteering," or special purpose map. This type of map falls somewhere between thematic and general maps. They combine general map elements with thematic attributes in order to design

318-536: A star map on the equidistant cylindrical projection. Although this method of charting seems to have existed in China even before this publication and scientist, the greatest significance of the star maps by Su Song is that they represent the oldest existent star maps in printed form. Early forms of cartography of India included depictions of the pole star and surrounding constellations. These charts may have been used for navigation. Mappae mundi ('maps of

424-535: A 'sense of the other' in relation to nonconforming maps." Depictions of Africa are a common target of deconstructionism . According to deconstructionist models, cartography was used for strategic purposes associated with imperialism and as instruments and representations of power during the conquest of Africa. The depiction of Africa and the low latitudes in general on the Mercator projection has been interpreted as imperialistic and as symbolic of subjugation due to

530-456: A Unified WGS Solution (a large scale least squares adjustment). The results of the adjustment consisted of corrections to initial station coordinates and coefficients of the gravitational field. The largest collection of data ever used for WGS purposes was assembled, processed and applied in the development of WGS 72. Both optical and electronic satellite data were used. The electronic satellite data consisted, in part, of Doppler data provided by

636-494: A World Geodetic System Committee composed of representatives from the United States Army, Navy and Air Force was charged with developing an improved WGS, needed to satisfy mapping , charting and geodetic requirements. Additional surface gravity observations, results from the extension of triangulation and trilateration networks, and large amounts of Doppler and optical satellite data had become available since

742-547: A consistent combination solution from different types of measurements all relative to the Earth's gravity field, measurements such as the geoid, gravity anomalies, deflections, and dynamic Doppler. The new world geodetic system was called WGS 84. It is the reference system used by the Global Positioning System . It is geocentric and globally consistent within 1  m . Current geodetic realizations of

848-428: A decreased focus on production skill, and an increased focus on quality design , the attempt to craft maps that are both aesthetically pleasing and practically useful for their intended purposes. A map has a purpose and an audience. Its purpose may be as broad as teaching the major physical and political features of the entire world, or as narrow as convincing a neighbor to move a fence. The audience may be as broad as

954-399: A different direction. To print from the finished plate, ink is spread over the metal surface and scraped off such that it remains only in the etched channels. Then the plate is pressed forcibly against the paper so that the ink in the channels is transferred to the paper. The pressing is so forceful that it leaves a "plate mark" around the border of the map at the edge of the plate, within which

1060-482: 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

1166-408: A general-purpose world map because regions are shown as increasingly larger than they actually are the further from the equator they are. Mercator is also credited as the first to use the word "atlas" to describe a collection of maps. In the later years of his life, Mercator resolved to create his Atlas, a book filled with many maps of different regions of the world, as well as a chronological history of

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1272-577: A high school geometry textbook in 1965, one of her many endeavors as an educator. After retiring in 1975, she wrote a memoir of her scientific career that was first serialized in the ACSM Bulletin (an official publication of the American Congress on Surveying and Mapping , which then included five surveying and mapping professional organizations, 2004 – 06) covering the field of geodesy in the years 1951–1975, and discussing doing science in

1378-761: A job at the then Army Map Service , now the National Geospatial-Intelligence Agency and the Army Geospatial Center in Potomac, Md., working under John A. O'Keefe in the Geodesy Branch and rising through the ranks to become the chief. Her twenty-five-year career at AMS, working on what became the World Geodetic System , produced over 120 scientific publications. On the side, she published

1484-400: A man's world in a government bureaucracy. It was published as a book in 2005. At the very beginning of her career in mathematics and geodesy, Dr. Fischer had quickly taught herself the basics of geodetic tables, datums , transformations, gravity studies, astronomy, long lines, flare triangulation, and guided missile ballistics. Her updates to geodetic science helped determine the parallax of

1590-581: A map is what comprise a map's deconstruction . A central tenet of deconstructionism is that maps have power. Other assertions are that maps are inherently biased and that we search for metaphor and rhetoric in maps. It is claimed that the Europeans promoted an " epistemological " understanding of the map as early as the 17th century. An example of this understanding is that "[European reproduction of terrain on maps] reality can be expressed in mathematical terms; that systematic observation and measurement offer

1696-441: A map with a specific audience in mind. Oftentimes, the type of audience an orienteering map is made for is in a particular industry or occupation. An example of this kind of map would be a municipal utility map. A topographic map is primarily concerned with the topographic description of a place, including (especially in the 20th and 21st centuries) the use of contour lines showing elevation. Terrain or relief can be shown in

1802-586: A metaphor for power. Political leaders could lay claim to territories through the use of maps, and this was greatly aided by the religious and colonial expansion of Europe. The Holy Land and other religious places were the most commonly mapped during the Renaissance. In the late 1400s to the late 1500s, Rome, Florence, and Venice dominated map-making and trade. It started in Florence in the mid-to late 1400s. Map trade quickly shifted to Rome and Venice but then

1908-466: A rare move, Ortelius credited mapmakers who contributed to the atlas, the list of which grew to 183 individuals by 1603. In the Renaissance , maps were used to impress viewers and establish the owner's reputation as sophisticated, educated, and worldly. Because of this, towards the end of the Renaissance, maps were displayed with equal importance of painting, sculptures, and other pieces of art. In

2014-745: A regional to a global enterprise." Born and educated in Vienna, she studied descriptive and projective geometry at the Technical University of Vienna and mathematics at the University of Vienna. Her teachers Moritz Schlick and Hans Hahn were among the luminaries of the Vienna Circle ; and her fellow students included physicist Victor Weisskopf , sociologist Paul Lazarsfeld , and social psychologist Marie Jahoda . Her father, Rabbi Armand Aharon Kaminka  [ de ] ,

2120-534: A standard as compared to the 1:50,000 scale Canadian maps. The government of the UK produces the classic 1:50,000 (replacing the older 1 inch to 1 mile) " Ordnance Survey " maps of the entire UK and with a range of correlated larger- and smaller-scale maps of great detail. Many private mapping companies have also produced thematic map series. Thematic cartography involves maps of specific geographic themes, oriented toward specific audiences. A couple of examples might be

2226-416: A thin sheet of wax over the metal plate and uses ink to draw the details. Then, the engraver traces the lines with a stylus to etch them into the plate beneath. The engraver can also use styli to prick holes along the drawn lines, trace along them with colored chalk, and then engrave the map. Lines going in the same direction are carved at the same time, and then the plate is turned to carve lines going in

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2332-400: A variety of ways (see Cartographic relief depiction ). In the present era, one of the most widespread and advanced methods used to form topographic maps is to use computer software to generate digital elevation models which show shaded relief. Before such software existed, cartographers had to draw shaded relief by hand. One cartographer who is respected as a master of hand-drawn shaded relief

2438-450: Is a close reproduction of a 1698 work by Nicolas de Fer . De Fer, in turn, had copied images that were first printed in books by Louis Hennepin , published in 1697, and François Du Creux, in 1664. By the late 18th century, mapmakers often credited the original publisher with something along the lines of, "After [the original cartographer]" in the map's title or cartouche . In cartography, technology has continually changed in order to meet

2544-473: Is an iconic example. Although the most widely used map of "The Tube," it preserves little of reality: it varies scale constantly and abruptly, it straightens curved tracks, and it contorts directions. The only topography on it is the River Thames , letting the reader know whether a station is north or south of the river. That and the topology of station order and interchanges between train lines are all that

2650-461: Is left of the geographic space. Yet those are all a typical passenger wishes to know, so the map fulfills its purpose. Modern technology, including advances in printing , the advent of geographic information systems and graphics software , and the Internet , has vastly simplified the process of map creation and increased the palette of design options available to cartographers. This has led to

2756-423: Is relatively oriented with respect to different portions of the geoid by the astro-geodetic methods already described.) The sole contribution of satellite data to the development of WGS 60 was a value for the ellipsoid flattening which was obtained from the nodal motion of a satellite. Prior to WGS 60, the U.S. Army and U.S. Air Force had each developed a world system by using different approaches to

2862-614: Is the IERS Reference Meridian , 5.3 arc seconds or 102 metres (335 ft) east of the Greenwich meridian at the latitude of the Royal Observatory . (This is related to the fact that the local gravity field at Greenwich does not point exactly through the Earth's center of mass, but rather "misses west" of the center of mass by about 102 meters.) The longitude positions on WGS 84 agree with those on

2968-469: Is the Swiss professor Eduard Imhof whose efforts in hill shading were so influential that his method became used around the world despite it being so labor-intensive. A topological map is a very general type of map, the kind one might sketch on a napkin. It often disregards scale and detail in the interest of clarity of communicating specific route or relational information. Beck's London Underground map

3074-460: Is the earliest known map is a matter of some debate, both because the term "map" is not well-defined and because some artifacts that might be maps might actually be something else. A wall painting that might depict the ancient Anatolian city of Çatalhöyük (previously known as Catal Huyuk or Çatal Hüyük) has been dated to the late 7th millennium BCE. Among the prehistoric alpine rock carvings of Mount Bego (France) and Valcamonica (Italy), dated to

3180-456: Is to patch together data that were not only made separately, for different regions, but to re-reference the elevations to an ellipsoid model rather than to the geoid . In accomplishing WGS 60, a combination of available surface gravity data, astro-geodetic data and results from HIRAN and Canadian SHORAN surveys were used to define a best-fitting ellipsoid and an earth-centered orientation for each initially selected datum. (Every datum

3286-621: Is updated separately. The current version of WGS 84 uses EGM2008 and WMM2020. Solution for Earth orientation parameters consistent with ITRF2014 is also needed (IERS EOP 14C04). Components of WGS 84 are identified by codes in the EPSG Geodetic Parameter Dataset : Cartography The fundamental objectives of traditional cartography are to: Modern cartography constitutes many theoretical and practical foundations of geographic information systems (GIS) and geographic information science (GISc). What

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3392-561: The Berlin Conference of 1884–1885. Before 1749, maps of the African continent had African kingdoms drawn with assumed or contrived boundaries, with unknown or unexplored areas having drawings of animals, imaginary physical geographic features, and descriptive texts. In 1748, Jean B. B. d'Anville created the first map of the African continent that had blank spaces to represent the unknown territory. In understanding basic maps,

3498-553: The Far East (which he learned through contemporary accounts from Arab merchants and explorers) with the information he inherited from the classical geographers, he was able to write detailed descriptions of a multitude of countries. Along with the substantial text he had written, he created a world map influenced mostly by the Ptolemaic conception of the world, but with significant influence from multiple Arab geographers. It remained

3604-522: The Kassite period (14th – 12th centuries BCE). The oldest surviving world maps are from 9th century BCE Babylonia . One shows Babylon on the Euphrates , surrounded by Assyria , Urartu and several cities, all, in turn, surrounded by a "bitter river" ( Oceanus ). Another depicts Babylon as being north of the center of the world. The ancient Greeks and Romans created maps from

3710-746: 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

3816-873: The University of Karlsruhe , elected to the National Academy of Engineering , elected Fellow of the American Geophysical Union , and inducted into the National Imagery and Mapping Agency (NIMA) Hall of Fame; the Learning Center at the new campus of the National Geospatial-Intelligence Agency has been named in her honor. She and her family were active for many years at Temple Israel in Silver Spring , Md., where she also taught an adult class in basic Hebrew, and

3922-583: The Werner projection . This was an equal-area, heart-shaped world map projection (generally called a cordiform projection) that was used in the 16th and 17th centuries. Over time, other iterations of this map type arose; most notable are the sinusoidal projection and the Bonne projection . The Werner projection places its standard parallel at the North Pole; a sinusoidal projection places its standard parallel at

4028-506: The lunar parallax , were instrumental in conducting these missions. "In his preface to the ACSM publication, Fischer's former colleague, Bernard Chovitz , referred to her as one of the most renowned geodesists of the third quarter of the twentieth century. Yet this fact alone makes her one of the most renowned geodesists of all times, because, according to Chovitz, the third quarter of the twentieth century witnessed "the transition of geodesy from

4134-477: 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

4240-455: The spirit level , plumb line , or an equivalent device that depends on the local gravity field (see physical geodesy ). As a result, the elevations in the data are referenced to the geoid , a surface that is not readily found using satellite geodesy . The latter observational method is more suitable for global mapping. Therefore, a motivation, and a substantial problem in the WGS and similar work

4346-476: The 17th century, European cartographers both copied earlier maps (some of which had been passed down for centuries) and drew their own based on explorers' observations and new surveying techniques. The invention of the magnetic compass , telescope and sextant enabled increasing accuracy. In 1492, Martin Behaim , a German cartographer and advisor to the king John II of Portugal , made the oldest extant globe of

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4452-612: The 1843-founded Vienna Israelitische Kinderbewahranstalt , the first professional kindergarten and kindergarten teacher training school in Vienna, a place that also became a refuge for immigrants to Vienna from Eastern Europe. In 1939, the Fischers, with their young daughter, Gay, fled Nazi Austria, traveling by rail to Italy, by boat to Palestine and in 1941 by boat around East Africa and the Cape of Good Hope to Boston, where they lived with Eric Fischer's sister, mother, and brother in law,

4558-526: The 4th millennium BCE, geometric patterns consisting of dotted rectangles and lines are widely interpreted in archaeological literature as depicting cultivated plots. Other known maps of the ancient world include the Minoan "House of the Admiral" wall painting from c.  1600 BCE , showing a seaside community in an oblique perspective, and an engraved map of the holy Babylonian city of Nippur , from

4664-524: The Age-Old Quest for the Size and Shape of the Earth, With a Running Commentary on Life in a Government Research Office. In addition, Fischer has written more than 120 other technical reports, articles and books in her fields of expertise, and many of her significant government reports are still classified today. Winner of many federal government service awards, Fischer was awarded an honorary degree by

4770-619: The Amur River as the border between the Eurasian powers, and opened up trading relations between the two. This treaty's significance draws from the interaction between the two sides, and the intermediaries who were drawn from a wide variety of nationalities. Maps of the Enlightenment period practically universally used copper plate intaglio, having abandoned the fragile, coarse woodcut technology. Use of map projections evolved, with

4876-510: The DoD World Geodetic System 1960 (WGS 60). The term datum as used here refers to a smooth surface somewhat arbitrarily defined as zero elevation, consistent with a set of surveyor's measures of distances between various stations, and differences in elevation, all reduced to a grid of latitudes , longitudes , and elevations . Heritage surveying methods found elevation differences from a local horizontal determined by

4982-517: The Doppler point positioning method. In the early 1980s, the need for a new world geodetic system was generally recognized by the geodetic community as well as within the US Department of Defense. WGS 72 no longer provided sufficient data, information, geographic coverage, or product accuracy for all then-current and anticipated applications. The means for producing a new WGS were available in

5088-566: The Earth is defined to be ω = 72.921 15 × 10 rad/s . This leads to several computed parameters such as the polar semi-minor axis b which equals a × (1 − f ) = 6 356 752 .3142 m , and the first eccentricity squared, e = 6.694 379 990 14 × 10 . The original standardization document for WGS 84 was Technical Report 8350.2, published in September 1987 by the Defense Mapping Agency (which later became

5194-505: The Earth. In 1507, Martin Waldseemüller produced a globular world map and a large 12-panel world wall map ( Universalis Cosmographia ) bearing the first use of the name "America." Portuguese cartographer Diogo Ribero was the author of the first known planisphere with a graduated Equator (1527). Italian cartographer Battista Agnese produced at least 71 manuscript atlases of sea charts. Johannes Werner refined and promoted

5300-455: The Moon. Irene Fischer was also intrigued by research into post glacial uplift , and her geoid studies went hand in hand with investigations of the lingering effects of the last ice age . Fischer disagreed with the established figure for the oblateness of the Earth (the fraction by which the polar axis is foreshortened by the equatorial radius), which had remained unchallenged since 1924. She

5406-718: The National Imagery and Mapping Agency). New editions were published in September 1991 and July 1997; the latter edition was amended twice, in January 2000 and June 2004. The standardization document was revised again and published in July 2014 by the National Geospatial-Intelligence Agency as NGA.STND.0036. These updates provide refined descriptions of the Earth and realizations of the system for higher precision. The original WGS84 model had an absolute accuracy of 1–2 meters. WGS84 (G730) first incorporated GPS observations, taking

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5512-660: 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

5618-900: The U.S. Army in 1970. Optical satellite data from the Worldwide Geometric Satellite Triangulation Program was provided by the BC-4 camera system (see image). Data from the Smithsonian Astrophysical Observatory was also used which included camera ( Baker–Nunn ) and some laser ranging. The surface gravity field used in the Unified WGS Solution consisted of a set of 410 10° × 10° equal area mean free air gravity anomalies determined solely from terrestrial data. This gravity field includes mean anomaly values compiled directly from observed gravity data wherever

5724-539: The U.S. Navy and cooperating non-DoD satellite tracking stations established in support of the Navy's Navigational Satellite System (NNSS). Doppler data was also available from the numerous sites established by GEOCEIVERS during 1971 and 1972. Doppler data was the primary data source for WGS 72 (see image). Additional electronic satellite data was provided by the SECOR (Sequential Collation of Range) Equatorial Network completed by

5830-505: The WGS Ellipsoid. Eight solutions were made with the various sets of input data, both from an investigative point of view and also because of the limited number of unknowns which could be solved for in any individual solution due to computer limitations. Selected Doppler satellite tracking and astro-geodetic datum orientation stations were included in the various solutions. Based on these results and other related studies accomplished by

5936-513: The accuracy down to 10 cm/component rms. All following revisions including WGS84 (G873) and WGS84 (G1150) also used GPS. WGS 84 (G1762) is the sixth update to the WGS reference frame. WGS 84 has most recently been updated to use the reference frame G2296 , which was released on 7 January 2024 as an update to G2139, now aligned to both the ITRF2020, the most recent ITRF realization, and the IGS20,

6042-541: The basic data for producing the WGS 66 gravimetric geoid. Also, a geoid referenced to the WGS 66 Ellipsoid was derived from available astrogeodetic data to provide a detailed representation of limited land areas. After an extensive effort over a period of approximately three years, the Department of Defense World Geodetic System 1972 was completed. Selected satellite, surface gravity and astrogeodetic data available through 1972 from both DoD and non-DoD sources were used in

6148-422: The committee, an a -value of 6 378 135  m and a flattening of 1/298.26 were adopted. In the development of local-to WGS 72 datum shifts, results from different geodetic disciplines were investigated, analyzed and compared. Those shifts adopted were based primarily on a large number of Doppler TRANET and GEOCEIVER station coordinates which were available worldwide. These coordinates had been determined using

6254-518: The coordinates of neighboring observation sites of the BC-4, SECOR, Doppler and Baker–Nunn systems. Also, eight geodimeter long line precise traverses were included for the purpose of controlling the scale of the solution. The Unified WGS Solution, as stated above, was a solution for geodetic positions and associated parameters of the gravitational field based on an optimum combination of available data. The WGS 72 ellipsoid parameters, datum shifts and other associated constants were derived separately. For

6360-505: The culmination of many map-making techniques incorporated into Chinese mercantile cartography. In 1689, representatives of the Russian tsar and Qing Dynasty met near the border town of Nerchinsk, which was near the disputed border of the two powers, in eastern Siberia. The two parties, with the Qing negotiation party bringing Jesuits as intermediaries, managed to work a treaty which placed

6466-433: 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

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6572-486: The development of WGS 60. Using the additional data and improved techniques, WGS 66 was produced which served DoD needs for about five years after its implementation in 1967. The defining parameters of the WGS 66 Ellipsoid were the flattening ( 1 ⁄ 298.25 determined from satellite data) and the semimajor axis ( 6 378 145  m determined from a combination of Doppler satellite and astro-geodetic data). A worldwide 5° × 5° mean free air gravity anomaly field provided

6678-801: The diminished proportions of those regions compared to higher latitudes where the European powers were concentrated. Maps furthered imperialism and colonization of Africa in practical ways by showing basic information like roads, terrain, natural resources, settlements, and communities. Through this, maps made European commerce in Africa possible by showing potential commercial routes and made natural resource extraction possible by depicting locations of resources. Such maps also enabled military conquests and made them more efficient, and imperial nations further used them to put their conquests on display. These same maps were then used to cement territorial claims, such as at

6784-432: The double hemisphere being very common and Mercator's prestigious navigational projection gradually making more appearances. Due to the paucity of information and the immense difficulty of surveying during the period, mapmakers frequently plagiarized material without giving credit to the original cartographer. For example, a famous map of North America known as the "Beaver Map" was published in 1715 by Herman Moll . This map

6890-479: The early seventeenth century, the Selden map was created by a Chinese cartographer. Historians have put its date of creation around 1620, but there is debate in this regard. This map's significance draws from historical misconceptions of East Asian cartography, the main one being that East Asians did not do cartography until Europeans arrived. The map's depiction of trading routes, a compass rose, and scale bar points to

6996-530: The equator; and the Bonne projection is intermediate between the two. In 1569, mapmaker Gerardus Mercator first published a map based on his Mercator projection , which uses equally-spaced parallel vertical lines of longitude and parallel latitude lines spaced farther apart as they get farther away from the equator. By this construction, courses of constant bearing are conveniently represented as straight lines for navigation. The same property limits its value as

7102-518: 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

7208-409: The form of improved data, increased data coverage, new data types and improved techniques. Observations from Doppler, satellite laser ranging and very-long-baseline interferometry (VLBI) constituted significant new information. An outstanding new source of data had become available from satellite radar altimetry. Also available was an advanced least squares method called collocation that allowed for

7314-704: The frame used by the International GNSS Service (IGS). G2139 was aligned with the IGb14 realization of the International Terrestrial Reference Frame (ITRF) 2014 and uses the new IGS Antex standard. Updates to the original geoid for WGS 84 are now published as a separate Earth Gravitational Model (EGM), with improved resolution and accuracy. Likewise, the World Magnetic Model (WMM)

7420-424: The general public or as narrow as a single person. Mapmakers use design principles to guide them in constructing a map that is effective for its purpose and audience. The cartographic process spans many stages, starting from conceiving the need for a map and extending all the way through its consumption by an audience. Conception begins with a real or imagined environment. As the cartographer gathers information about

7526-454: The geocentric reference system family International Terrestrial Reference System (ITRS) maintained by the IERS are geocentric, and internally consistent, at the few-cm level, while still being metre-level consistent with WGS 84. The WGS 84 reference ellipsoid was based on GRS 80 , but it contains a very slight variation in the inverse flattening, as it was derived independently and

7632-481: The gravimetric datum orientation method. To determine their gravimetric orientation parameters, the Air Force used the mean of the differences between the gravimetric and astro-geodetic deflections and geoid heights (undulations) at specifically selected stations in the areas of the major datums. The Army performed an adjustment to minimize the difference between astro-geodetic and gravimetric geoids . By matching

7738-416: The latter was available in sufficient quantity. The value for areas of sparse or no observational data were developed from geophysically compatible gravity approximations using gravity-geophysical correlation techniques. Approximately 45 percent of the 410 mean free air gravity anomaly values were determined directly from observed gravity data. The astrogeodetic data in its basic form consists of deflection of

7844-540: 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

7950-527: The map, whether in physical or electronic form. Once finished, the map is delivered to its audience. The map reader interprets the symbols and patterns on the map to draw conclusions and perhaps to take action. By the spatial perspectives they provide, maps help shape how we view the world. Irene Fischer Irene Kaminka Fischer (born July 27, 1907, in Vienna , Austria , died October 22, 2009, in Boston )

8056-451: The most accurate world map for the next three centuries. The map was divided into seven climatic zones, with detailed descriptions of each zone. As part of this work, a smaller, circular map depicting the south on top and Arabia in the center was made. Al-Idrisi also made an estimate of the circumference of the world, accurate to within 10%. In the Age of Discovery , from the 15th century to

8162-509: The older North American Datum 1927 at roughly 85° longitude west , in the east-central United States. The WGS 84 datum surface is an oblate spheroid with equatorial radius a = 6 378 137  m at the equator and flattening f = 1 ⁄ 298.257 223 563 . The refined value of the WGS ;84 gravitational constant (mass of Earth's atmosphere included) is GM = 3.986 004 418 × 10 m/s . The angular velocity of

8268-445: The only route to cartographic truth…". A common belief is that science heads in a direction of progress, and thus leads to more accurate representations of maps. In this belief, European maps must be superior to others, which necessarily employed different map-making skills. "There was a 'not cartography' land where lurked an army of inaccurate, heretical, subjective, valuative, and ideologically distorted images. Cartographers developed

8374-415: The paper is depressed compared to the margins. Copper and other metals were expensive at the time, so the plate was often reused for new maps or melted down for other purposes. Whether woodcut or intaglio, the printed map is hung out to dry. Once dry, it is usually placed in another press to flatten the paper. Any type of paper that was available at the time could be used to print the map, but thicker paper

8480-770: The physician Otto Ehrentheil and their two daughters. Looking for jobs, Fischer first worked as a seamstress’ assistant, then she graded blue books for Wassily Leontief at Harvard and for Norbert Wiener at the Massachusetts Institute of Technology (MIT). She also worked on stereoscopic projective geometry trajectories for John Rule at MIT. She taught mathematics at Brown and Nichols Preparatory School in Cambridge, and then at Sidwell Friends in Washington, D.C. After World War II, and after her son, Michael, born in 1946, had reached school age, she found

8586-492: The prints rather than having to create a new one. On the other hand, it is hard to achieve fine detail with the relief technique. Inconsistencies in linework are more apparent in woodcut than in intaglio. To improve quality in the late fifteenth century, a style of relief craftsmanship developed using fine chisels to carve the wood, rather than the more commonly used knife. In intaglio, lines are engraved into workable metals, typically copper but sometimes brass. The engraver spreads

8692-721: 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. Field-rugged computers , GPS , and laser rangefinders make it possible to create maps directly from measurements made on site. There are technical and cultural aspects to producing maps. In this sense, maps can sometimes be said to be biased. The study of bias, influence, and agenda in making

8798-593: The relative astro-geodetic geoids of the selected datums with an earth-centered gravimetric geoid, the selected datums were reduced to an earth-centered orientation. Since the Army and Air Force systems agreed remarkably well for the NAD, ED and TD areas, they were consolidated and became WGS 60. Improvements to the global system included the Astrogeoid of Irene Fischer and the astronautic Mercury datum. In January 1966,

8904-405: The result was rounded to a different number of significant digits. This resulted in a tiny difference of 0.105 mm in the semi-minor axis. The following table compares the primary ellipsoid parameters. The coordinate origin of WGS 84 is meant to be located at the Earth's center of mass ; the uncertainty is believed to be less than 2 cm . The WGS 84 meridian of zero longitude

9010-680: The satellites had not accepted the accepted literature, either. A pioneer during a time when there were few women in surveying, in 1967, Fischer was the first Army Map Service employee, and only the third woman ever, to receive the Distinguished Civilian Service Award . Fischer was internationally known for her many publications and presentations on the size and shape of the earth, including the Department of Defense manual, “Latitude Functions Fischer 1960 Ellipsoid.” Fischer wrote an autobiography (published 2005), entitled, Geodesy? What’s That? My Personal Involvement in

9116-408: The sheet. Being raised from the rest of the block, the map lines cause indentations in the paper that can often be felt on the back of the map. There are advantages to using relief to make maps. For one, a printmaker doesn't need a press because the maps could be developed as rubbings. Woodblock is durable enough to be used many times before defects appear. Existing printing presses can be used to create

9222-479: The sixteenth century, maps were becoming increasingly available to consumers through the introduction of printmaking, with about 10% of Venetian homes having some sort of map by the late 1500s. There were three main functions of maps in the Renaissance: In medieval times, written directions of how to get somewhere were more common than the use of maps. With the Renaissance, cartography began to be seen as

9328-404: The subject, they consider how that information is structured and how that structure should inform the map's design. Next, the cartographers experiment with generalization , symbolization , typography , and other map elements to find ways to portray the information so that the map reader can interpret the map as intended. Guided by these experiments, the cartographer settles on a design and creates

9434-558: The time of Anaximander in the 6th century BCE. In the 2nd century CE, Ptolemy wrote his treatise on cartography, Geographia . This contained Ptolemy's world map – the world then known to Western society ( Ecumene ) . As early as the 8th century, Arab scholars were translating the works of the Greek geographers into Arabic. Roads were essential in the Roman world, motivating the creation of maps, called itinerarium , that portrayed

9540-459: The troubles of a coarse medium and so was able to express the looping cursive that came to be known as cancellaresca . There were custom-made reverse punches that were also used in metal engraving alongside freehand lettering. The first use of color in map-making cannot be narrowed down to one reason. There are arguments that color started as a way to indicate information on the map, with aesthetics coming second. There are also arguments that color

9646-407: The unified solution, a normal equation matrix was formed based on each of the mentioned data sets. Then, the individual normal equation matrices were combined and the resultant matrix solved to obtain the positions and the parameters. The value for the semimajor axis ( a ) of the WGS 72 Ellipsoid is 6 378 135  m . The adoption of an a -value 10 meters smaller than that for the WGS 66 Ellipsoid

9752-557: The various national surveying systems began in the 19th century with F.R. Helmert's book Mathematische und Physikalische Theorien der Physikalischen Geodäsie ( Mathematical and Physical Theories of Physical Geodesy ). Austria and Germany founded the Zentralbüro für die Internationale Erdmessung (Central Bureau of International Geodesy ), and a series of global ellipsoids of the Earth were derived (e.g., Helmert 1906, Hayford 1910 and 1924). A unified geodetic system for

9858-400: The vertical components referred to the various national geodetic datums. These deflection values were integrated into astrogeodetic geoid charts referred to these national datums. The geoid heights contributed to the Unified WGS Solution by providing additional and more detailed data for land areas. Conventional ground survey data was included in the solution to enforce a consistent adjustment of

9964-515: The whole world became essential in the 1950s for several reasons: In the late 1950s, the United States Department of Defense , together with scientists of other institutions and countries, began to develop the needed world system to which geodetic data could be referred and compatibility established between the coordinates of widely separated sites of interest. Efforts of the U.S. Army, Navy and Air Force were combined leading to

10070-634: The world as experienced via the roads. The Tabula Peutingeriana is the only surviving example. In ancient China , geographical literature dates to the 5th century BCE. The oldest extant Chinese maps come from the State of Qin , dated back to the 4th century BCE, during the Warring States period . In the book Xin Yi Xiang Fa Yao , published in 1092 by the Chinese scientist Su Song ,

10176-515: The world from the Earth's creation by God until 1568. He was unable to complete it to his satisfaction before he died. Still, some additions were made to the Atlas after his death, and new editions were published after his death. In 1570, the Brabantian cartographer Abraham Ortelius , strongly encouraged by Gillis Hooftman , created the first true modern atlas, Theatrum Orbis Terrarum . In

10282-464: The world') are the medieval European maps of the world. About 1,100 of these are known to have survived: of these, some 900 are found illustrating manuscripts, and the remainder exist as stand-alone documents. The Arab geographer Muhammad al-Idrisi produced his medieval atlas Tabula Rogeriana (Book of Roger) in 1154. By combining the knowledge of Africa , the Indian Ocean , Europe , and

10388-603: Was an Austrian-American mathematician and geodesist . She was a member of the National Academy of Engineering , a Fellow of the American Geophysical Union , and inductee of the National Imagery and Mapping Agency Hall of Fame. Fischer became one of two internationally known women scientists in the field of geodesy during the golden age of the Project Mercury and the Apollo program . Her Mercury datum (or Fischer ellipsoid 1960 and 1968), as well as her work on

10494-627: Was an active member of a forty-year-long chavura (discussion group). When she moved to Rockville, Md., she joined Congregation Beth El and endowed a Biblical archeology lecture series in her husband's memory at the Rockville Jewish Community Center. In Israel, where many family members live, she and her husband endowed fellowships to a technical college. In 2001, she moved back to Brighton, Mass., three blocks from where she had first lived as an immigrant in 1941. In 2007, she celebrated her 100th birthday, and her children told

10600-420: Was based on several calculations and indicators including a combination of satellite and surface gravity data for position and gravitational field determinations. Sets of satellite derived station coordinates and gravimetric deflection of the vertical and geoid height data were used to determine local-to-geocentric datum shifts, datum rotation parameters, a datum scale parameter and a value for the semimajor axis of

10706-522: Was first used on maps for aesthetics but then evolved into conveying information. Either way, many maps of the Renaissance left the publisher without being colored, a practice that continued all the way into the 1800s. However, most publishers accepted orders from their patrons to have their maps or atlases colored if they wished. Because all coloring was done by hand, the patron could request simple, cheap color, or more expensive, elaborate color, even going so far as silver or gold gilding. The simplest coloring

10812-431: Was forbidden to use her updated figures in her own work because that result was in disagreement with the accepted literature. However, after the flight of the first satellites , she was vindicated by the data and observations from the instruments, and she was allowed to amend her previous works with her newly derived figures. In commenting on the lack of faith others put on her research, Dr. Fischer goodheartedly quipped that

10918-669: Was head of the Maimonides Institute , and regularly led high holiday services at the famed Vienna Musikverein . He worked for the Alliance Israélite Universelle investigating pogroms in Eastern Europe and raised money in the U.S. and Western Europe to help victims. In 1931 she married historian and geographer Eric Fischer , who helped introduce American, as distinct from British, history to Vienna. The Fischer family established and ran

11024-469: Was merely outlines, such as of borders and along rivers. Wash color meant painting regions with inks or watercolors. Limning meant adding silver and gold leaf to the map to illuminate lettering, heraldic arms, or other decorative elements. The early modern period saw the convergence of cartographical techniques across Eurasia and the exchange of mercantile mapping techniques via the Indian Ocean. In

11130-493: Was more durable. Both relief and intaglio were used about equally by the end of the fifteenth century. Lettering in mapmaking is important for denoting information. Fine lettering is difficult in woodcut, where it often turned out square and blocky, contrary to the stylized, rounded writing style popular in Italy at the time. To improve quality, mapmakers developed fine chisels to carve the relief. Intaglio lettering did not suffer

11236-609: Was overtaken by atlas makers in the late 16th century. Map publishing in Venice was completed with humanities and book publishing in mind, rather than just informational use. There were two main printmaking technologies in the Renaissance: woodcut and copper-plate intaglio , referring to the medium used to transfer the image onto paper. In woodcut, the map image is created as a relief chiseled from medium-grain hardwood. The areas intended to be printed are inked and pressed against

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