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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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Africa Precipitation Map
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area and 20% of its land area.Sayre, April Pulley (1999), ''Africa'', Twenty-First Century Books. . With billion people as of , it accounts for about of the world's human population. Africa's population is the youngest amongst all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Despite a wide range of natural resources, Africa is the least wealthy continent per capita and second-least wealthy by total wealth, behind Oceania. Scholars have attributed this to different factors including geography, climate, tribalism, colonialism, the Cold War, neocolonialism, lack of democracy, and corruption. Despite this low concentration of wealth, recent economic expansion and the large and young population make A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Function (mathematics)
In mathematics, a function from a set to a set assigns to each element of exactly one element of .; the words map, mapping, transformation, correspondence, and operator are often used synonymously. The set is called the domain of the function and the set is called the codomain of the function.Codomain ''Encyclopedia of Mathematics'Codomain. ''Encyclopedia of Mathematics''/ref> The earliest known approach to the notion of function can be traced back to works of Persian mathematicians Al-Biruni and Sharaf al-Din al-Tusi. Functions were originally the idealization of how a varying quantity depends on another quantity. For example, the position of a planet is a ''function'' of time. Historically, the concept was elaborated with the infinitesimal calculus at the end of the 17th century, and, until the 19th century, the functions that were considered were differentiable (that is, they had a high degree of regularity). The concept of a function was formalized at the end of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vector Graphics
Vector graphics is a form of computer graphics in which visual images are created directly from geometric shapes defined on a Cartesian plane, such as points, lines, curves and polygons. The associated mechanisms may include vector display and printing ''hardware'', vector ''data models'' and file formats, as well as the ''software'' based on these data models (especially graphic design software, computer-aided design, and geographic information systems). Vector graphics is an alternative to raster or bitmap graphics, with each having advantages and disadvantages in specific situations. While vector hardware has largely disappeared in favor of raster-based monitors and printers, vector data and software continues to be widely used, especially when a high degree of geometric precision is required, and when complex information can be decomposed into simple geometric primitives. Thus, it is the preferred model for domains such as engineering, architecture, surveying, 3D re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geographic Information Science
Geographic information science or geographical information science (GIScience or GISc) is the scientific discipline 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 can be contrasted with geographic information systems (GIS), which are the actual repositories of such data, the software tools for carrying out relevant tasks, and the profession of GIS users. That said, one of the major goals of GIScience is to find practical ways to improve GIS data, software, and professional practice. it is more focused on how gis is applied in real life British geographer Michael Goodchild defined this area in the 1990s and summarized its core interests, including spatial analysis, visualization, and the representation of uncertainty. GIScience is conceptually related to geomatics, information science, computer science, but it claims the s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geostatistics
Geostatistics is a branch of statistics focusing on spatial or spatiotemporal datasets. Developed originally to predict probability distributions of ore grades for mining operations, it is currently applied in diverse disciplines including petroleum geology, hydrogeology, hydrology, meteorology, oceanography, geochemistry, geometallurgy, geography, forestry, environmental control, landscape ecology, soil science, and agriculture (esp. in precision farming). Geostatistics is applied in varied branches of geography, particularly those involving the spread of diseases (epidemiology), the practice of commerce and military planning (logistics), and the development of efficient spatial networks. Geostatistical algorithms are incorporated in many places, including geographic information systems (GIS). Background Geostatistics is intimately related to interpolation methods, but extends far beyond simple interpolation problems. Geostatistical techniques rely on statistical mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Map Algebra
Map algebra is an algebra for manipulating geographic data, primarily fields. Developed by Dr. Dana Tomlin and others in the late 1970s, it is a set of primitive operations in a geographic information system (GIS) which allows one or more raster layers ("maps") of similar dimensions to produce a new raster layer (map) using mathematical or other operations such as addition, subtraction etc. History Prior to the advent of GIS, the overlay principle had developed as a method of literally superimposing different thematic maps (typically an isarithmic map or a chorochromatic map) drawn on transparent film (e.g., cellulose acetate) to see the interactions and find locations with specific combinations of characteristics. The technique was largely developed by landscape architects and city planners, starting with Warren Manning and further refined and popularized by Jaqueline Tyrwhitt, Ian McHarg and others during the 1950s and 1960s. In the mid-1970s, landscape architec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ian McHarg
Ian L. McHarg (20 November 1920 – 5 March 2001) was a Scottish landscape architect and writer on regional planning using natural systems. McHarg was one of the most influential persons in the environmental movement who brought environmental concerns into broad public awareness and ecological planning methods into the mainstream of landscape architecture, city planning and public policy. He was the founder of the department of landscape architecture at the University of Pennsylvania in the United States. His 1969 book ''Design with Nature'' pioneered the concept of ecological planning. It continues to be one of the most widely celebrated books on landscape architecture and land-use planning. In this book, he set forth the basic concepts that were to develop later in geographic information systems. Biography Formative years His father was a manager and later a salesman in the industrial city of Glasgow, Scotland. McHarg showed an early talent for drawing and was advised to consid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cartographic Modeling
Cartography (; from grc, χάρτης , "papyrus, sheet of paper, map"; and , "write") is the study and practice of making and using maps. Combining science, aesthetics and technique, cartography builds on the premise that reality (or an imagined reality) can be modeled in ways that communicate spatial information effectively. The fundamental objectives of traditional cartography are to: * Set the map's agenda and select traits of the object to be mapped. This is the concern of map editing. Traits may be physical, such as roads or land masses, or may be abstract, such as toponyms or political boundaries. * Represent the terrain of the mapped object on flat media. This is the concern of map projections. * Eliminate characteristics of the mapped object that are not relevant to the map's purpose. This is the concern of generalization. * Reduce the complexity of the characteristics that will be mapped. This is also the concern of generalization. * Orchestrate the elements of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Canadian Geographic Information Systems
{{Unreferenced, date=October 2012 The Canada Geographic Information System (CGIS) was an early geographic information system (GIS) developed for the Government of Canada beginning in the early 1960s. CGIS was used to store geospatial data for the Canada Land Inventory and assisted in the development of regulatory procedures for land-use management and resource monitoring in Canada. At that time, Canada was beginning to realize problems associated with its large land mass and attempting to discern the availability of natural resources. The federal government decided to launch a national program to assist in management and inventory of its resources. The simple automated computer processes designed to store and process large amounts of data enabled Canada to begin a national land-use management program and become a foremost promoter of geographic information systems (GIS). CGIS was designed to withstand great amounts of collected data by managing, modeling, and analyzing this dat ... [...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 represents a two-dimensional picture as a rectangular matrix or grid of square pixels, viewable via a computer display, paper, or other display medium. A raster 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 manipulations map directly onto the mathematical formalisms of lin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gravity Model
Gravity models are used in various social sciences to predict and describe certain behaviors that mimic gravitational interaction as described in Isaac Newton's laws of gravity. Generally, the social science models contain some elements of mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different ele ... and distance, which lends them to the metaphor of physical gravity. A gravity model provides an estimate of the volume of flows of, for example, goods, services, or people between two or more locations. This could be the movement of people between cities or the volume of trade between countries. A gravity model cannot accurately predict flows, but is instead a measure against which actual observed values can be compared, highlighting where those flows are unexpectedly high or low. Social sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantitative Revolution
The quantitative revolution (QR) was a paradigm shift that sought to develop a more rigorous and systematic methodology for the discipline of geography. It came as a response to the inadequacy of regional geography to explain general spatial dynamics. The main claim for the quantitative revolution is that it led to a shift from a descriptive ( idiographic) geography to an empirical law-making (nomothetic) geography. The quantitative revolution occurred during the 1950s and 1960s and marked a rapid change in the method behind geographical research, from regional geography into a spatial science. "The ‘Quantitative Revolution’", GG3012(NS) Lecture 4, University of Aberdeen, 2011, webpage: AB12 In the history of geography, the quantitative revolution was one of the four major turning points of modern geography – the other three being environmental determinism, regional geography and critical geography. It culminated in the emergence of the technical geography branc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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