40 Fun Facts About GIS (Geographic Information Systems)

Which physician mapped cholera deaths around London's Broad Street pump in 1854?

John Snow marked each death on a street plan and the cluster pointed to one water pump. Parish officials removed its handle the day after he made his case.

Which name do GIS users give the spot at 0°N 0°E, where records with blank coordinates pile up?

Null Island is no island at all: a weather buoy named Soul was moored at the spot. One public map dataset lists it as a one-metre-square island to trap errors.

Which virtual globe program began at Keyhole, a startup once funded by the CIA's venture arm?

Google Earth launched in 2005, the year after Google bought Keyhole. The startup's name lives on in KML, short for Keyhole Markup Language, the file format the program reads.

Which third-party US presidential candidate inspired Esri's founder to launch GIS Day in 1999?

Ralph Nader is the person Jack Dangermond credits with the idea behind the event. It is held each year on the third Wednesday of November.

Which 1569 world map design, drawn for sailors, makes Greenland look as big as Africa?

Mercator stretches land more the farther it lies from the Equator, so Greenland matches Africa on paper although Africa is 14 times larger. Most web maps still use a version of the design.

Which US president had the deliberate error in civilian GPS signals switched off in May 2000?

Bill Clinton ended the policy called Selective Availability, giving civilians the accuracy the military had. Ronald Reagan had promised public access after a Korean airliner strayed into Soviet airspace in 1983.

Which country built the first working GIS in the 1960s to manage an inventory of its rural land?

Canada began the system in Ottawa in 1963 to hold maps of soils, farming, wildlife and forestry at a scale of 1:50,000. Its lead designer is remembered as the father of GIS.

Which US university built the map dashboard the world used to track COVID-19 from January 2020?

Johns Hopkins engineer Lauren Gardner built it with a first-year graduate student, Ensheng Dong. The map went live on January 22, 2020 and has logged more than 200 billion data requests.

Which volunteer-built world map did Steve Coast start in 2004 because British map data was not free?

OpenStreetMap began at University College London after the Ordnance Survey declined to release its data under a free licence. Volunteers started by mapping the United Kingdom.

Which London district's observatory meridian was voted the world's zero of longitude in 1884?

Greenwich won the vote at a conference in Washington, D.C., but France abstained and kept the Paris meridian on its own maps for decades.

Which curves on a topographic map join points of equal height and bunch together on steep slopes?

Contours each follow a single height, so tight spacing means a cliff and wide spacing a plain. Dutch engineer Nicholas Cruquius charted a riverbed the same way in the early 1700s.

Which word did a NASA lab engineer first publish in 1965 for each square of a space-probe image?

Pixel blends 'pix' and 'element', and Frederic Billingsley printed it to describe scans from Moon and Mars probes. In GIS imagery every one stores a measured value, such as brightness.

In vector GIS data, which geometry type stores a lake or land parcel as a closed loop?

Polygon outlines close back on themselves to enclose a two-dimensional region. The other basic shapes are points, each a single coordinate, and lines, an ordered list of coordinates.

Which map style, common in crime analysis, colours an area by how densely data points cluster?

Heat map shading is an old idea: in 1873 Toussaint Loua hand-coloured a grid of social statistics for the districts of Paris.

Which satellite navigation system did the European Union build under civilian control to rival GPS?

Galileo is named after the Italian astronomer Galileo Galilei. Europe wanted a positioning service that no foreign military could degrade or switch off.

Which ranging technology, built into iPhone Pro models, do survey aircraft use to map terrain?

Lidar times laser pulses as they bounce back from a surface. The public first saw its precision in 1971, when Apollo 15 astronauts used a laser altimeter to chart the Moon.

Which US agency built the TIGER digital street map of the whole country, first used in 1990?

The Census Bureau made TIGER the first nationwide digital map of roads, boundaries and water. It still publishes the files, which also record city limits, rivers and lakes.

Which path, the Equator being one example, is the shortest route between two points on a globe?

Great circle routes cut the globe into two hemispheres, and any meridian joined to its opposite forms one too. Ships and aircraft follow them to cover the least distance.

Which technique triggers an alert when a phone or vehicle crosses a virtual boundary drawn on a map?

Geofencing draws a virtual perimeter around a real place and reports when a tracked device enters or leaves it. Rangers use it to learn when wildlife strays into farmland.

Which GIS data model, named from the Latin for a rake, stores the world as a grid of cells?

Raster reached English through German from rastrum, a rake. Satellite photos and scanned maps arrive in this form, with one measured value stored in every cell.

Which GIS tool, a core function since the late 1970s, draws a zone of set distance around a feature?

Buffer zones are probably the most used tool in proximity analysis. Around a single point the result is a disc whose radius is the chosen distance.

Which process, also run in 'reverse', turns a street address into map coordinates?

Geocoding matches text against stored address points, street networks and postal boundaries. The reverse kind starts from a latitude and longitude and returns the name of the place.

Which map type, first drawn in 1826 to show schooling in France, shades each area by a statistic?

Choropleth maps got their name in 1938 from the geographer J. K. Wright. Baron Charles Dupin had drawn the earliest known example more than a century before.

Which commercial GIS software from Esri began in 1982 as a command-line program?

ArcGIS started out as ARC/INFO, driven by typed commands, and its ArcMap desktop program for Windows arrived in late 1999. Its maker, Esri, held an estimated 43% of the GIS software market in 2015.

Which free, open-source desktop GIS did Gary Sherman begin developing in early 2002?

QGIS was called Quantum GIS until version 2.0 in 2013 settled on the short form. It became an incubator project of the Open Source Geospatial Foundation in 2007.

Which Esri map data format from the early 1990s needs at least three separate files to work?

Shapefile data borrows its .dbf table from the old DOS database program dBase. By the late 1990s it had become the geospatial industry's most popular format for sharing data.

Which former Royal Air Force pilot is known as the father of GIS, having coined the term itself?

Roger Tomlinson flew for the RAF from 1951 to 1954 and later ran computer mapping at an aerial survey company in Ottawa. There he saw that computers could handle mapping jobs too detailed for people.

Which satellite programme, begun in 1972, is the longest-running source of Earth imagery?

Landsat began as the Earth Resources Technology Satellite, launched on 23 July 1972. Its unbroken record lets analysts compare the same place across five decades.

Which GIS record, standardised as ISO 19115, describes a dataset's quality, extent and lineage?

Metadata means data about data, and libraries kept it on catalogue cards long before computers. US federal agencies drew up their own geospatial standard for it between 1992 and 1994.

Which band of light, strongly reflected by healthy leaves, is compared with red to map vegetation?

Near-infrared light bounces off the cell structure of leaves, while the pigment chlorophyll soaks up visible light for photosynthesis. The contrast between the two is the basis of the NDVI plant index.

Which Space Shuttle flew the 11-day radar mission in February 2000 that mapped Earth's terrain?

Endeavour carried one antenna in its payload bay and a second on a 200-foot mast unfolded in orbit. It was the orbiter's last flight not devoted to the International Space Station.

In which Southern California city did Jack and Laura Dangermond found Esri in 1969 with just $1,100?

Redlands is still the company's headquarters, and its user conference began on the campus there in 1981 with 16 attendees. Esri started out as a land-use consulting firm.

Which global coordinate standard, kept by a US intelligence agency, do GPS receivers rely on?

WGS 84 puts its origin at Earth's centre of mass. Its zero of longitude lies about 102 metres east of the historic meridian line at London's Royal Observatory.

Which university housed Howard Fisher's computer graphics lab, a 1965 pioneer of mapping software?

Harvard ran the lab within its Graduate School of Design until 1991, sending programs such as SYMAP to universities and firms worldwide. Esri's founder did early work there.

Which model of Earth's shape, first described by Gauss, follows sea level under gravity alone?

Geoid surfaces are smooth but irregular because mass is spread unevenly inside the planet. Map heights above sea level are measured from it, while raw GPS heights use a simpler ellipsoid.

Which geographer's 'first law', an aside in a 1970 Detroit paper, says nearby things are more alike?

Waldo Tobler was describing a computer movie of the city's growth when he tossed in the remark. It now underpins spatial interpolation, where unknown values are estimated from close neighbours.

The EPSG codes that label map coordinate systems are named after a survey group from which industry?

Petroleum surveyors started the registry in 1985, when Jean-Patrick Girbig of the oil company Elf built it to share spatial data between firms. Code 4326 is the plain latitude and longitude used by GPS.

Which interpolation method is named after a South African mining engineer who plotted gold grades?

Kriging honours Danie Krige, who judged the gold in the Witwatersrand reef from a few boreholes. French mathematician Georges Matheron built the theory in 1960 from Krige's master's thesis.

Which Scottish landscape architect's 1969 book Design with Nature spread the map overlay method?

Ian McHarg wrote the book as step-by-step instructions for dividing a region into its fitting uses. He also founded the landscape architecture department at the University of Pennsylvania.

Which branch of mathematics names the GIS rules on how features touch, connect and avoid overlap?

Topology rules catch errors such as overlapping areas and lines that dangle short of a junction. Early data models built on them also saved storage by recording a shared boundary only once.