|
Cartographic Generalisation
Cartographic generalization, or map generalization, includes all changes in a map that are made when one derives a smaller-scale map from a larger-scale map or map data. It is a core part of cartographic design. Whether done manually by a cartographer or by a computer or set of algorithms, generalization seeks to abstract spatial information at a high level of detail to information that can be rendered on a map at a lower level of detail. The cartographer has license to adjust the content within their maps to create a suitable and useful map that conveys spatial information, while striking the right balance between the map's purpose and the precise detail of the subject being mapped. Well generalized maps are those that emphasize the most important map elements while still representing the world in the most faithful and recognizable way. History During the first half of the 20th century, cartographers began to think seriously about how the features they drew depended on scale. E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 Map projection, projected. The ratio of the Earth's size to the generating globe's size is called the nominal scale (also called principal scale or representative fraction). Many maps state the nominal scale and may even display a bar scale (sometimes merely called a "scale") to represent it. The second distinct concept of scale applies to the variation in scale across a map. It is the ratio of the mapped point's scale to the nominal scale. In this case 'scale' means the scale factor (also ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edward Tufte
Edward Rolf Tufte (; born March 14, 1942), sometimes known as "ET",. is an American statistician and professor emeritus of political science, statistics, and computer science at Yale University. He is noted for his writings on information design and as a pioneer in the field of data visualization. Early life and education Edward Rolf Tufte was born in 1942 in Kansas City, Missouri, to Virginia Tufte (1918–2020) and Edward E. Tufte (1912–1999). He grew up in Beverly Hills, California, where his father was a longtime city official. He graduated from the public Beverly Hills High School.Reynolds, Christopher."ART; Onward means going upward; Edward Tufte has spent his career fighting the visually dull and flat. Even his sculpture is a leap." ''Los Angeles Times'', November 14, 2002. Accessed April 23, 2008. " dward Tufte who shares in Cheshire, Conn., with his wife, graphic design professor Inge Druckrey, and three golden retrievers, is a 1960 graduate of Beverly Hills High ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Waldo Tobler
Waldo Rudolph Tobler (November 16, 1930 – February 20, 2018) was an United States, American-Switzerland, Swiss geographer and cartographer. Tobler is regarded as one of the most influential geographers and cartographers of the late 20th century and early 21st century. He is most well known for coining what has come to be referred to as Tobler's first law of geography. He also coined what has come to be referred to as Tobler's second law of geography. Tobler's career had a major impact on the development of quantitative geography, and his research spanned and influenced the study of any discipline investigating geographic phenomena. He established the discipline of analytical cartography, contributed early to Geographic information systems (GIS), and helped lay the groundwork for geographic information science (GIScience) as a discipline. He had significant contributions to computer cartography and was one of the first geographers to explore using computers in geography. In cart ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel Smoother
A kernel smoother is a statistical technique to estimate a real valued function f: \mathbb^p \to \mathbb as the weighted average of neighboring observed data. The weight is defined by the ''kernel'', such that closer points are given higher weights. The estimated function is smooth, and the level of smoothness is set by a single parameter. Kernel smoothing is a type of weighted moving average. Definitions Let K_(X_0 ,X) be a kernel defined by :K_(X_0 ,X) = D\left( \frac \right) where: * X,X_0 \in \mathbb^p * \left\, \cdot \right\, is the Euclidean norm * h_\lambda (X_0) is a parameter (kernel radius) * ''D''(''t'') is typically a positive real valued function, whose value is decreasing (or not increasing) for the increasing distance between the ''X'' and ''X''0. Popular kernels used for smoothing include parabolic (Epanechnikov), tricube, and Gaussian kernels. Let Y(X):\mathbb^p \to \mathbb be a continuous function of ''X''. For each X_0 \in \mathbb^p, the Nadaraya-Watson ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Field (geography)
In the context of spatial analysis, geographic information systems, and geographic information science, a field is a property that fills space, and varies over space, such as temperature or density. This use of the term has been adopted from physics and mathematics, due to their similarity to physical fields (vector or scalar) such as the electromagnetic field or gravitational field. Synonymous terms include spatially dependent variable (geostatistics), statistical surface ( thematic mapping), and intensive property (physics and chemistry) and crossbreeding between these disciplines is common. The simplest formal model for a field is the function, which yields a single value given a point in space (i.e., ''t'' = ''f''(''x'', ''y'', ''z'') ) History The modeling and analysis of fields in geographic applications was developed in five essentially separate movements, all of which arose during the 1950s and 1960s: * Cartographic techniques for visualizing fields in thematic maps, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raster Graphics
upright=1, The Smiley, smiley face in the top left corner is a raster image. When enlarged, individual pixels appear as squares. Enlarging further, each pixel can be analyzed, with their colors constructed through combination of the values for red, green and blue. In computer graphics and digital photography, a raster graphic, raster image, or simply raster is a two-dimensional image or picture represented as a rectangular Matrix (mathematics), matrix or grid of pixels, viewable via a computer display, paper, or other display medium. A raster image is technically characterized by the width and height of the image in pixels and by the number of bits per pixel. Raster images are stored in image files with varying dissemination, production, generation, and acquisition formats. The printing and prepress industries know raster graphics as contones (from "continuous tones"). In contrast, '' line art'' is usually implemented as vector graphics in digital systems. Many raster ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ramer–Douglas–Peucker Algorithm
The Ramer–Douglas–Peucker algorithm, also known as the Douglas–Peucker algorithm and iterative end-point fit algorithm, is an algorithm that decimates a curve composed of line segments to a similar curve with fewer points. It was one of the earliest successful algorithms developed for cartographic generalization. It produces the most accurate generalization, but it is also more time-consuming. Algorithm The starting curve is an ordered set of points or lines and the distance dimension . The algorithm recursively divides the line. Initially it is given all the points between the first and last point. It automatically marks the first and last point to be kept. It then finds the point that is farthest from the line segment with the first and last points as end points; this point is always farthest on the curve from the approximating line segment between the end points. If the point is closer than to the line segment, then any points not currently marked to be kept can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Earth
Natural Earth is a public domain map data set, dataset available at 1:10 million (1 cm = 100 km), 1:50 million, and 1:110 million map scales. Natural Earth's data set contains integrated vector and raster mapping data. The original authors of the map dataset are Tom Patterson (cartographer), Tom Patterson and Nathaniel Vaughn Kelso, but Natural Earth has expanded to be a collaboration of many volunteers and is supported by the North American Cartographic Information Society (NACIS). It is free for public use in any type of project. The dataset includes the fictitious 1-meter-square Null Island at for error-checking purposes. Public domain data and software All versions of Natural Earth Raster graphics, raster and Vector graphics, vector map data on the Nat ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
