Scale (map)The scale of a map is the ratio of a distance on the map to the corresponding distance on the ground. This simple concept is complicated by the curvature of the Earth's surface, which forces scale to vary across a map. Because of this variation, the concept of scale becomes meaningful in two distinct ways. The first way is the ratio of the size of the generating globe to the size of the Earth. The generating globe is a conceptual model to which the Earth is shrunk and from which the map is projected.
Tissot's indicatrixIn cartography, a Tissot's indicatrix (Tissot indicatrix, Tissot's ellipse, Tissot ellipse, ellipse of distortion) (plural: "Tissot's indicatrices") is a mathematical contrivance presented by French mathematician Nicolas Auguste Tissot in 1859 and 1871 in order to characterize local distortions due to map projection. It is the geometry that results from projecting a circle of infinitesimal radius from a curved geometric model, such as a globe, onto a map.
Sinusoidal projectionThe sinusoidal projection is a pseudocylindrical equal-area map projection, sometimes called the Sanson–Flamsteed or the Mercator equal-area projection. Jean Cossin of Dieppe was one of the first mapmakers to use the sinusoidal, appearing in a world map of 1570. The projection represents the poles as points, as they are on the sphere, but the meridians and continents are distorted. The equator and the prime meridian are the most accurate parts of the map, having no distortion at all, and the further away from those that one examines, the greater the distortion.
Geographic information scienceGeographic information science (GIScience, GISc) or geoinformation science is a scientific discipline at the crossroads of computational science, social science, and natural science that studies geographic information, including how it represents phenomena in the real world, how it represents the way humans understand the world, and how it can be captured, organized, and analyzed. It is a sub-field of geography, specifically part of technical geography.
Geography (Ptolemy)The Geography (Γεωγραφικὴ Ὑφήγησις, Geōgraphikḕ Hyphḗgēsis, () "Geographical Guidance"), also known by its Latin names as the Geographia and the Cosmographia, is a gazetteer, an atlas, and a treatise on cartography, compiling the geographical knowledge of the 2nd-century Roman Empire. Originally written by Claudius Ptolemy in Greek at Alexandria around AD 150, the work was a revision of a now-lost atlas by Marinus of Tyre using additional Roman and Persian gazetteers and new principles.
Fictitious entryFictitious or fake entries are deliberately incorrect entries in reference works such as dictionaries, encyclopedias, maps, and directories, added by the editors as a copyright trap to reveal subsequent plagiarism or copyright infringement. There are more specific terms for particular kinds of fictitious entry, such as Mountweazel, trap street, paper town, phantom settlement, and nihilartikel. The neologism Mountweazel was coined by The New Yorker writer Henry Alford in an article that mentioned a fictitious biographical entry intentionally placed as a copyright trap in the 1975 New Columbia Encyclopedia.
Visual variableA visual variable, in cartographic design, graphic design, and data visualization, is an aspect of a graphical object that can visually differentiate it from other objects, and can be controlled during the design process. The concept was first systematized by Jacques Bertin, a French cartographer and graphic designer, and published in his 1967 book, Sémiologie Graphique. Bertin identified a basic set of these variables and provided guidance for their usage; the concept and the set of variables has since been expanded, especially in cartography, where it has become a core principle of education and practice.
United States Geological SurveyThe United States Geological Survey (USGS), founded as the Geological Survey, is an agency of the United States government whose work spans the disciplines of biology, geography, geology, and hydrology. The agency was founded on March 3, 1879, to study the landscape of the United States, its natural resources, and the natural hazards that threaten it. The agency also makes maps of extraterrestrial planets and moons based on data from U.S. space probes.
Landsat programThe Landsat program is the longest-running enterprise for acquisition of of Earth. It is a joint NASA / USGS program. On 23 July 1972, the Earth Resources Technology Satellite was launched. This was eventually renamed to Landsat 1 in 1975. The most recent, Landsat 9, was launched on 27 September 2021. The instruments on the Landsat satellites have acquired millions of images.
Geographic Information Science and Technology Body of KnowledgeNOTOC The Geographic Information Science and Technology Body of Knowledge (GISTBoK) is a reference document produced by the University Consortium for Geographic Information Science (UCGIS) as the first product of its Model Curricula project, started in 1997 by Duane Marble and a select task force, and completed in 2006 by David DiBiase and a team of editors. The GISTBoK is the most successful effort to date to create a comprehensive outline of the concepts and skills unique to the geospatial realm, including geographic information systems, geographic information science, remote sensing, satellite navigation systems, and cartography.
