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Choropleth
A choropleth map () is a type of statistical thematic map that uses pseudocolor, i.e., color corresponding with an aggregate summary of a geographic characteristic within spatial enumeration units, such as population density or per-capita income. Choropleth maps provide an easy way to visualize how a variable varies across a geographic area or show the level of variability within a region. A heat map or isarithmic map is similar but uses regions drawn according to the pattern of the variable, rather than the '' a priori'' geographic areas of choropleth maps. The choropleth is likely the most common type of thematic map because published statistical data (from government or other sources) is generally aggregated into well-known geographic units, such as countries, states, provinces, and counties, and thus they are relatively easy to create using GIS, spreadsheets, or other software tools. History The earliest known choropleth map was created in 1826 by Baron Pierre C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Choropleth Map
A choropleth map () is a type of statistical thematic map that uses pseudocolor, i.e., color corresponding with an aggregate summary of a geographic characteristic within spatial enumeration units, such as population density or per-capita income. Choropleth maps provide an easy way to visualize how a variable varies across a geographic area or show the level of variability within a region. A heat map or isarithmic map is similar but uses regions drawn according to the pattern of the variable, rather than the ''a priori'' geographic areas of choropleth maps. The choropleth is likely the most common type of thematic map because published statistical data (from government or other sources) is generally aggregated into well-known geographic units, such as countries, states, provinces, and counties, and thus they are relatively easy to create using GIS, spreadsheets, or other software tools. History The earliest known choropleth map was created in 1826 by Baron Pierre Charl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dasymetric Map
A dasymetric map () is a type of thematic map that uses areal symbols to visualize a geographic field by refining a choropleth map with ancillary information about the distribution of the variable. The name refers to the fact that the most common variable mapped using this technique has generally been population density. The dasymetric map is a hybrid product combining the strengths and weaknesses of choropleth and isarithmic maps.T. Slocum, R. McMaster, F. Kessler, H. Howard (2009). Thematic Cartography and Geovisualization, Third Edn, page 252. Pearson Prentice Hall: Upper Saddle River, NJ. Dasymetric maps are used instead of choropleth maps because they represent underlying data distributions more accurately. Choropleth maps and dasymetric maps differ in three main ways. First, dasymetric zones are generated using ancillary data while boundaries on choropleth maps use units used for more general purposes (such as U.S. county boundaries). Second, choropleth zones have var ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thematic Map
A thematic map is a type of map that portrays the geographic pattern of a particular subject matter (theme) in a geographic area. This usually involves the use of map symbols to visualize selected properties of geographic features that are not naturally visible, such as temperature, language, or population. In this, they contrast with general reference maps, which focus on the location (more than the properties) of a diverse set of physical features, such as rivers, roads, and buildings. Alternative names have been suggested for this class, such as ''special-subject'' or ''special-purpose maps'', ''statistical maps'', or ''distribution maps'', but these have generally fallen out of common usage. Thematic mapping is closely allied with the field of Geovisualization. Several types of thematic maps have been invented, starting in the 18th and 19th centuries, as large amounts of statistical data began to be collected and published, such as national censuses. These types, such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heat Map
A heat map (or heatmap) is a data visualization technique that shows magnitude of a phenomenon as color in two dimensions. The variation in color may be by hue or intensity, giving obvious visual cues to the reader about how the phenomenon is clustered or varies over space. There are two fundamentally different categories of heat maps: the cluster heat map and the spatial heat map. In a cluster heat map, magnitudes are laid out into a matrix of fixed cell size whose rows and columns are discrete phenomena and categories, and the sorting of rows and columns is intentional and somewhat arbitrary, with the goal of suggesting clusters or portraying them as discovered via statistical analysis. The size of the cell is arbitrary but large enough to be clearly visible. By contrast, the position of a magnitude in a spatial heat map is forced by the location of the magnitude in that space, and there is no notion of cells; the phenomenon is considered to vary continuously. "Heat map" is a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudocolor
False color (or pseudo color) refers to a group of color rendering methods used to display images in color which were recorded in the visible or non-visible parts of the electromagnetic spectrum. A false-color image is an image that depicts an object in colors that differ from those a photograph (a true-color image) would show. In this image, colors have been assigned to three different wavelengths that our eyes cannot normally see. In addition, variants of ''false color'' such as pseudocolor, density slicing, and choropleths are used for information visualization of either data gathered by a single grayscale channel or data not depicting parts of the electromagnetic spectrum (e.g. elevation in relief maps or tissue types in magnetic resonance imaging). Types of color renderings True color The concept behind true color can help in understanding false color. An image is called a ''true-color'' image when it offers a natural color rendition, or when it comes close to it. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chorochromatic Map
A Chorochromatic map (), also known as an area-class, qualitative area, or mosaic map, is a type of thematic map that portray regions of categorical or nominal data using variations in color symbols. Chorochromatic maps are typically used to represent discrete fields, also known as categorical coverages. Chorochromatic maps differ from choropleth maps in that chorochromatic maps are mapped according to data-driven boundaries instead of trying to make the data fit within existing, sometimes arbitrary units such as political boundaries. History The chorochromatic map is one of the oldest types of thematic map, first appearing independently in several different fields. In 1741, Gottfried Hensel published '' Synopsis Universae Philologiae'', a book about world languages that included a set of maps of language regions, each with boundaries and colors for broad language families as he understood them. Other maps of cultural regions began to appear in the 19th Century. The first ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Dupin
Baron Pierre Charles François Dupin (6 October 1784, Varzy, Nièvre – 18 January 1873, Paris, France) was a French Catholic mathematician, engineer, economist and politician, particularly known for work in the field of mathematics, where the Dupin cyclide and Dupin indicatrix are named after him; and for his work in the field of statistical and thematic mapping. Palsky, Gilles.Connections and Exchanges in European Thematic Cartography. The case of XIXth century choropleth maps" ''Formatting Europe. Mapping a continent.'' 2007 In 1826 he created the earliest known choropleth map. Michael Friendly (2008)"Milestones in the history of thematic cartography, statistical graphics, and data visualization" Life and work He was born in Varzy in France, the son of Charles Andre Dupin, a lawyer, and Catherine Agnes Dupin. Dupin studied geometry with Monge at the École Polytechnique and then became a naval engineer ( ENSTA). His mathematical work was in descriptive and differentia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Kirtland Wright
John Kirtland Wright (1891–1969) was an American geographer, notable for his cartography, geosophy, and study of the history of geographical thought. He was the son of classical scholar John Henry Wright and novelist Mary Tappan Wright, and the brother of legal scholar and utopian novelist Austin Tappan Wright. He married Katharine McGiffert Jan. 21, 1921 in New York, N.Y. They had three children: Austin McGiffert Wright, Gertrude Huntington McPherson, and Mary Wolcott Toynbee. Having completed a PhD in history at Harvard University, in 1920 Wright was employed as librarian by the American Geographical Society; between the years of 1920 and 1956 he also served as an AGS editor, personal academic contributor, and eventually director. As a result of his prolific academic and professional life, three main themes have emerged in John K. Wright’s published works. These include: the overlapping of academic disciplines (mainly history) with geography, the power of the mind and the su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modifiable Areal Unit Problem
__NOTOC__ The modifiable areal unit problem (MAUP) is a source of statistical bias that can significantly impact the results of statistical hypothesis tests. MAUP affects results when point-based measures of spatial phenomena are aggregated into districts, for example, population density or illness rates. The resulting summary values (e.g., totals, rates, proportions, densities) are influenced by both the shape and scale of the aggregation unit. For example, census data may be aggregated into county districts, census tracts, postcode areas, police precincts, or any other arbitrary spatial partition. Thus the results of data aggregation are dependent on the mapmaker's choice of which "modifiable areal unit" to use in their analysis. A census choropleth map calculating population density using state boundaries will yield radically different results than a map that calculates density based on county boundaries. Furthermore, census district boundaries are also subject to change ove ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contour Line
A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional graph of the function f(x,y) parallel to the (x,y)-plane. More generally, a contour line for a function of two variables is a curve connecting points where the function has the same particular value. In cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. A contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes. The contour interval of a contour map is the difference in elevation between successive contour lines. The gradient of the function is always perpendicular to the contour lines. When the lines are close together the magnitude of the gra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
