Wiki.GIS.com:Featured Content
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This page hosts the content that is used for the "Featured Content and related image" section of the main page. These entries are selected randomly and persist for a specific number of days.
- <fp><fptitle>Contour Line</fptitle>
<fpcontent>A contour line, of a function of two variables, is a curve along which the function has a constant 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 of slopes. The contour interval of a contour map is the difference in elevation between successive contour lines. More generally, a contour line for a function of two variables is a curve connecting points where the function has a same particular value. The gradient of the function is always perpendicular to the contour lines. When the lines are close together the length of the gradient is large: the variation is steep.</fpcontent>
<fpimage>File:Topographic_map_example.png</fpimage>
<fpthumb>frameless|200px|right</fpthumb>
<fpurl>Contour_line</fpurl></fp>[edit] Universal Transverse Mercator Coordinate System
- <fp><fptitle>Universal Transverse Mercator Coordinate System</fptitle>
<fpcontent>The Universal Transverse Mercator (UTM) coordinate system is a grid-based method of specifying locations on the surface of the Earth that is a practical application of a 2-dimensional Cartesian coordinate system. It is used to identify locations on the earth, but differs from the traditional method of latitude and longitude in several respects. The UTM system is not a single map projection. The system instead employs a series of sixty zones, each of which is based on a specifically defined secant transverse Mercator projection. The Universal Transverse Mercator coordinate system was developed by the United States Army Corps of Engineers in the 1940s. The system was based on an ellipsoidal model of the Earth. For areas within the conterminous United States, the Clarke 1866 ellipsoid was used. For the remaining areas of the Earth, including Hawaii, the International Ellipsoid was used. Currently, the WGS84 ellipsoid is used as the underlying model of the Earth in the UTM coordinate system</fpcontent>
<fpimage>File:Utm-zones.jpg</fpimage>
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<fpurl>Universal_Transverse_Mercator_coordinate_system</fpurl></fp>[edit] Dymaxion Map
- <fp><fptitle>Dymaxion Map</fptitle>
<fpcontent>The Dymaxion map of the earth, also known as the Fuller Projection, is a projection of a global map onto the surface of a polyhedron, which, when expanded to a flat, two-dimensional map, retains most of the relative proportional integrity (relative size and shape) of global features. Unlike most projections, the Dymaxion map of the world actually shows Antarctica as coequal to other continents and not distorted beyond recognition. The Dymaxion map projection was created by the visionary designer and inventor Buckminster Fuller and patented in 1946. The 1954 version published by Fuller under the title The Air-Ocean World Map used a slightly modified but mostly regular icosahedron as the base for the projection, and this is the version most commonly referred to today.</fpcontent>
<fpimage>File:Dymaxion.large.jpg</fpimage>
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<fpurl>Dymaxion_map</fpurl></fp>[edit] GIS in Archaeology
- <fp><fptitle>GIS in Archaeology</fptitle>
<fpcontent>GIS is an important tool in archaeology. Archaeologists were some of the early adopters, users, and developers of GIS and GIScience. The combination of GIS and archaeology has been considered a perfect match since archaeology is the study of the spatial dimension of human behavior over time, and all archaeology carries a spatial component. Since archaeology looks at the unfolding of historical events through geography, time and culture, the results of archaeological studies are rich in spatial information. GIS is adept at processing these large volumes of data, especially that which is geographically referenced. The tools made available through GIS help in data collection, its storage and retrieval, its manipulation for customized circumstances and, in the display of the data so that it is visually comprehensible by the user. The most important aspect of GIS in archaeology lies, however, not in its use as a pure map-making tool, but in its capability to merge and analyze different types of data in order to create new information.</fpcontent>
<fpimage>File:Map_Aliki_peninsula-fr.svg</fpimage>
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<fpurl>GIS_in_archaeology</fpurl></fp>[edit] Geographic Information Science
- <fp><fptitle>Geographic Information Science</fptitle>
<fpcontent>Geographic information science is the academic theory behind the development, use, and application of geographic information systems. It is concerned with people, hardware, software, and geospatial data. GISc addresses fundamental issues raised by the use of GIS and related information technologies. Three central issues of GISc are the modifiable areal unit problem, complete spatial randomness and spatial autocorrelation. GISc is relevant to researchers from many scientific disciplines because these three central issues are often ignored in the application of statistical hypothesis testing. GISc argues that both Bayesian and Traditional statistical inference should consider spatial structure of the data being analyzed. Complete spatial randomness is also referred to as global spatial homogeneity. And spatial autocorrelation is also referred to as global spatial heterogeneity.</fpcontent>
<fpimage>File:Wheeler_Peak.png</fpimage>
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<fpurl>Geographic_information_science</fpurl></fp>[edit] Digital Elevation Model
- <fp><fptitle>Digital Elevation Model</fptitle>
<fpcontent>A digital elevation model (DEM) is a digital representation of ground surface topography or terrain. It is also widely known as a digital terrain model (DTM). A DEM can be represented as a raster (a grid of squares) or as a triangular irregular network. DEMs are commonly built using remote sensing techniques, but they may also be built from land surveying. DEMs are used often in geographic information systems, and are the most common basis for digitally-produced relief maps.</fpcontent>
<fpimage>File:Nasa_anden.jpg</fpimage>
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<fpurl>Digital_elevation_model</fpurl></fp>[edit] Image Rectification
- <fp><fptitle>Image Rectification</fptitle>
<fpcontent>Image rectification is a transformation process used to project multiple images onto a common image surface. It is used to correct a distorted image into a standard coordinate system. It is used in computer stereo vision to simplify the problem of finding matching points between images. And it is used in geographic information systems to merge images taken from multiple perspectives into a common map coordinate system. Stereo vision uses triangulation based on epipolar geometry to determine distance to an object. Between two cameras there is a problem of finding a corresponding point viewed by one camera in the image of the other camera. In most camera configurations, finding correspondences requires a search in two dimensions. However, if the two cameras are aligned to have a common image plane, the search is simplified to one dimension - a line that is parallel to the line between the cameras. Image rectification is an equivalent alternative to this precise camera alignment. It transforms the images to make the epipolar lines align horizontally</fpcontent>
<fpimage>File:Image_rectification.png</fpimage>
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<fpurl>Image_rectification</fpurl></fp>[edit] Waldo R. Tobler
- <fp><fptitle>Waldo R. Tobler</fptitle>
<fpcontent>Waldo Tobler (born 1930) is an influential American-Swiss geographer and cartographer. Tobler's idea that "Everything is related to everything else, but near things are more related to each other" is referred to as the "first law of geography". Dr. Tobler is a Professor Emeritus at the University of California, Santa Barbara Department of Geography. In 1961, Tobler received his Ph.D. in Geography from the University of Washington at Seattle. At Washington, he participated in geography's William Garrison-led quantitative revolution of the late 1950s. After graduating, Tobler spent several years at the University of Michigan. Until his retirement he held the positions of Professor of Geography and Professor of Statistics at UCSB. The University of Zurich, Switzerland, awarded him a Doctorate honoris causa in 1988.</fpcontent>
<fpimage>File:Waldotobler1.jpg</fpimage>
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<fpurl>Waldo_R._Tobler</fpurl></fp>[edit] Triangulated Irregular Network
- <fp><fptitle>Triangulated Irregular Network</fptitle>
<fpcontent>A triangulated irregular network (TIN) is a digital data structure used in a GIS for the representation of a surface. A TIN is a vector based representation of the physical land surface or sea bottom, made up of irregularly distributed nodes and lines with three dimensional coordinates (x,y, and z) that are arranged in a network of nonoverlapping triangles. TINs are often derived from the elevation data of a rasterized digital elevation model (DEM). An advantage of using a TIN over a DEM in mapping and analysis is that the points of a TIN are distributed variably based on an algorithm that determines which points are most necessary to an accurate representation of the terrain. Data input is therefore flexible and fewer points need to be stored than in a DEM with regularly distributed points. While a TIN may be less suited than a DEM raster for certain kinds of GIS applications, such as analysis of a surface's slope and aspect, TINs have the advantage of being able to portray terrain in three dimensions.</fpcontent>
<fpimage>File:Example_of_Triangulated_Irregular_Network.jpg</fpimage>
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<fpurl>Triangulated_irregular_network</fpurl></fp>[edit] Spatial Analysis
- <fp><fptitle>Spatial Analysis</fptitle>
<fpcontent>In statistics, spatial analysis, or spatial statistics, includes any of the formal techniques which study entities using their topological, geometric, or geographic properties. The phrase properly refers to a variety of techniques, many still in their early development, using different analytic approaches and applied in fields as diverse as astronomy, with its studies of the placement of galaxies in the cosmos, to chip fabrication engineering, with its use of 'place and route' algorithms to build complex wiring structures. The phrase is often used in a more restricted sense to describe techniques applied to structures at the human scale, most notably in the analysis of geographic data. The phrase is even sometimes used to refer to a specific technique in a single area of research, for example, to describe statistics.</fpcontent>
<fpimage>File:Snow-cholera-map.jpg</fpimage>
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<fpurl>Spatial_analysis</fpurl></fp>[edit] Geography
- <fp><fptitle>Geography</fptitle>
<fpcontent>Geography, from the Greek geographia, literally "earth describe-write", is the study of the Earth and its lands, features, inhabitants, and phenomena. A literal translation would be "to describe or write about the Earth". The first person to use the word "geography" was Eratosthenes. Four historical traditions in geographical research are the spatial analysis of natural and human phenomena (geography as a study of distribution), area studies (places and regions), study of man-land relationship, and research in sciences. Nonetheless, modern geography is an all-encompassing discipline that foremost seeks to understand the Earth and all of its human and natural complexities—not merely where objects are, but how they have changed and come to be. As "the bridge between the human and physical sciences," geography is divided into two main branches—human geography and physical geography.</fpcontent>
<fpimage>File:World_rel_803005AI_2003.jpg</fpimage>
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<fpurl>Geography</fpurl></fp>[edit] State Plane Coordinate System
- <fp><fptitle>State Plane Coordinate System</fptitle>
<fpcontent>The State Plane Coordinate System (SPS or SPCS) is a set of 126 geographic zones or coordinate systems designed for specific regions of the United States. Each state contains one or more state plane zones, the boundaries of which usually follow county lines. There are 110 zones in the continental US, with 10 more in Alaska, 5 in Hawaii, and one for Puerto Rico and US Virgin Islands. The system is widely used for geographic data by state and local governments. Its popularity is due to at least two factors. First, it uses a simple cartesian coordinate system to specify locations rather than a more complex spherical coordinate system. By thus ignoring the curvature of the Earth, "plane surveying" methods can be used, speeding up and simplifying calculations. Second, the system is highly accurate within each zone (error less than 1:10,000). Outside a specific state plane zone accuracy rapidly declines, thus the system is not useful for regional or national mapping.</fpcontent>
<fpimage>File:State_plane.jpg</fpimage>
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<fpurl>State_Plane_Coordinate_System</fpurl></fp>[edit] Orthophoto
- <fp><fptitle>Orthophoto</fptitle>
<fpcontent>An orthophoto, or orthophotograph, is an aerial photograph geometrically corrected ("orthorectified") such that the scale is uniform: the photo has the same lack of distortion as a map. Unlike an uncorrected aerial photograph, an orthophotograph can be used to measure true distances, because it is an accurate representation of the earth's surface, having been adjusted for topographic relief, lens distortion, and camera tilt. Orthophotographs are commonly used in the creation of a GIS. Software can display the orthophoto and allow an operator to digitize or place linework, text annotations or geographic symbols (such as hospitals, schools, and fire stations). Some software can process the orthophoto and produce the linework automatically.</fpcontent>
<fpimage>File:AerialDigitalPhoto.JPG</fpimage>
<fpthumb>frameless|200px|right</fpthumb>
<fpurl>Orthophoto</fpurl></fp>[edit] Topography
- <fp><fptitle>Topography</fptitle>
<fpcontent>Topography (from the Greek topo- "place" and graphia, "writing") is the study of Earth's surface shape and features or those of planets, moons, and asteroids. It is also the description of such surface shapes and features, especially their depiction in maps. The topography of an area can also mean the surface shape and features themselves. In a broader sense, topography is concerned with local detail in general, including not only relief but also vegetative and human-made features, and even local history and culture. This meaning is less common in America, where topographic maps with elevation contours have made "topography" synonymous with relief. The older sense of topography as the study of place still has currency in Europe.</fpcontent>
<fpimage>File:Topographic_map_example.png</fpimage>
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<fpurl>Topography</fpurl></fp>[edit] Visual Hierarchy
- <fp><fptitle>Visual Hierarchy</fptitle>
<fpcontent>Visual hierarchy is the order in which the human eye perceives what it sees. It is used in cartography to help the map designer create a product where the viewer will process the information presented in order from the most important to the least important. This can be achieved by manipulating different pieces of a map such as its color contrast, symbology, texture, shape, position, scale, orientation and size.</fpcontent>
<fpimage>File:OpenStreetMap_Tile.png</fpimage>
<fpthumb>frameless|150px|right</fpthumb>
<fpurl>Visual_hierarchy</fpurl></fp>[edit] Cartography
- <fp><fptitle>Cartography</fptitle>
<fpcontent>Cartography is the study and practice of making geographical maps. Combining science, aesthetics, and technique, cartography builds on the premise that reality can be modeled in ways that communicate spatial information effectively. Cartography addresses the following issues: 1) Setting the map's agenda and selecting 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. 2) Representing the terrain of the mapped object on flat media. This is the concern of map projections. 3) Eliminating characteristics of the mapped object that are not relevant to the map's purpose. This is the concern of generalization. 4) Reducing the complexity of the characteristics that will be mapped. This is also the concern of generalization. 5) Orchestrating the elements of the map to best convey its message to its audience. This is the concern of map design.</fpcontent>
<fpimage>File:Mediterranean_chart_fourteenth_century2.jpg</fpimage>
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<fpurl>Cartography</fpurl></fp>[edit] System Design Strategies
- <fp><fptitle>System Design Strategies</fptitle>
<fpcontent>System architecture design is a process developed by Esri to promote successful GIS enterprise operations. This process builds on your existing information technology (IT) infrastructure and provides specific recommendations for hardware and network solutions based on existing and projected business (user) needs. Application requirements, data resources, and people within an organization are all important in determining the optimum hardware solution as shown in figure 1-1. Early GIS customer implementation experiences highlighted the importance of understanding the relationship between user business workflow requirements and the supporting hardware and network infrastructure loads. A process was established to understand GIS business needs, identify common user workflows (application and data architecture patterns), and apply a system architecture design methodology to identify technology solutions that contribute to successful GIS operations.</fpcontent>
<fpimage>File:SpringSDS10Fig1-1_SAD.jpg</fpimage>
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<fpurl>System_Design_Strategies</fpurl></fp>[edit] Feature class
- <fp><fptitle>Feature class</fptitle>
<fpcontent>Feature classes are homogeneous collections of common features, each having the same spatial representation, such as points, lines, or polygons, and a common set of attribute columns, for example, a line feature class for representing road centerlines. The four most commonly used feature classes in the geodatabase are points, lines, polygons, and annotation (the geodatabase name for map text). Vector features (geographic objects with vector geometry) are versatile and frequently used geographic data types, well suited for representing features with discrete boundaries, such as wells, streets, rivers, states, and parcels. A feature is simply an object that stores its geographic representation, which is typically a point, line, or polygon, as one of its properties (or fields) in the row. In ArcGIS, feature classes are homogeneous collections of features with a common spatial representation and set of attributes stored in a database table.</fpcontent>
<fpimage>File:FeatClassPointLinePoly.gif</fpimage>
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<fpurl>Feature_class</fpurl></fp>[edit] Jenks Natural Breaks Classification
- <fp><fptitle>Jenks Natural Breaks Classification</fptitle>
<fpcontent>The Jenks Natural Breaks Classification (or Optimization) system is a data classification method designed to optimize the arrangement of a set of values into ""natural"" classes. This is done by seeking to minimize the average deviation from the class mean, while maximizing the deviation from the means of the other groups. The method reduces the variance within classes and maximizes the variance between classes.[1][2] The Jenks scheme determines the best arrangement of values into classes by iteratively comparing sums of the squared difference between observed values within each class and class means. The best classification identifies breaks in the ordered distribution of values that minimizes within-class sum of squared differences. Cartographers and map makers can utilize the Jenks method to identify break points in a data set by picking the class breaks that best group similar values and maximize the differences between classes.</fpcontent>
<fpimage>File:Natural_breaks_map.gif</fpimage>
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<fpurl>Jenks_Natural_Breaks_Classification</fpurl></fp>[edit] Python
- <fp><fptitle>Python</fptitle>
<fpcontent>Python is a general-purpose high-level programming language, designed to be easily read. Python runs on Windows, Linux/Unix, Mac OS X, and has been ported to the Java and .NET virtual machines. [1] Python was introduced to ArcGIS with version 9.0. A full ArcGIS installation includes Python, its standard libraries, and the NumPy package. Starting with ArcGIS 9.2, a compatible version of PythonWin is included in the ArcGIS distribution, but must be installed separately. ESRI recommends using the version of Python (and additional packages) shipped together with the specific version of ArcGIS.[2] Python is used as the primary ArcGIS scripting language to perform geoprocessing tasks. It is capable of accessing all the ArcToolbox tools as well as the methods on the Geoprocessor Programming Model. The GDAL/OGR libraries have python bindings. This means that you can use all of the GDAL/OGR functions and object classes via python. Being open source software, you don't have to worry about license availability, or not having the latest versions.</fpcontent>
<fpimage>Image:Earth_night.jpg</fpimage>
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<fpurl>Python</fpurl></fp>[edit] LIDAR
- <fp><fptitle>LIDAR</fptitle>
<fpcontent>Light Detection and Ranging LIDAR is an optical remote sensing technology used to collect a wide range of topographic data. LIDAR is similar to radar technology, which uses radio waves, a form of electromagnetic radiation that is not in the visible spectrum. The range to an object is determined by measuring the time delay between transmission of a pulse and detection of the reflected signal. LIDAR technology has applications in Archaeology, Geography, Geology, Geomorphology, Seismology, remote sensing and many more areas. Light detection and ranging (LIDAR), also known as airborne laser scanning (ALS), is an emerging remote sensing technology with promising potential to assisting mapping, monitoring, and assessment of forest resources. Compared to traditional analog or digital passive optical remote sensing, LIDAR offers tangible advantages, including nearly perfect registration of spatially distributed data and the ability to penetrate the vertical profile of a forest canopy and quantify its structure.</fpcontent>
<fpimage>File:Aerial_lidar_NOAA.gif</fpimage>
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<fpurl>LIDAR</fpurl></fp>[edit] Feature dataset
- <fp><fptitle>Feature dataset</fptitle>
<fpcontent>A feature dataset is a collection of related feature classes that share a common coordinate system. Feature datasets are used to spatially or thematically integrate related feature classes. Their primary purpose is for organizing related feature classes into a common dataset for building a topology, a network dataset, a terrain dataset, or a geometric network. There are additional situations in which users apply feature datasets in their geodatabases: • To organize thematically related feature classes Sometimes, users will organize a collection of feature classes for a common theme into a single feature dataset. For example, users might have a feature dataset for Water that contains Hydro Points, Hydro Lines, and Hydro Polygons. • To organize data access based on database privileges Sometimes, users organize data access privileges using feature datasets. All feature classes contained within a feature dataset have the same access privileges</fpcontent>
<fpimage>File:Feature_dataset.png</fpimage>
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<fpurl>Feature_dataset</fpurl></fp>[edit] Topology
- <fp><fptitle>Topology</fptitle>
<fpcontent>Topology (from the Greek τόπος, “place”, and λόγος, “study”)[1] is the mathematical study of the properties that are preserved through deformations, twistings, and stretchings of objects. Tearing, however, is not allowed. A circle is topologically equivalent to an ellipse (into which it can be deformed by stretching) and a sphere is equivalent to an ellipsoid. Similarly, the set of all possible positions of the hour hand of a clock is topologically equivalent to a circle (i.e., a one-dimensional closed curve with no intersections that can be embedded in two-dimensional space), the set of all possible positions of the hour and minute hands taken together is topologically equivalent to the surface of a torus (i.e., a two-dimensional a surface that can be embedded in three-dimensional space), and the set of all possible positions of the hour, minute, and second hands taken together are topologically equivalent to a three-dimensional object.</fpcontent>
<fpimage>File:Mobius_strip.jpg</fpimage>
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<fpurl>Topology</fpurl>></fp>[edit] Cadastral fabric
- <fp><fptitle>Cadastral fabric</fptitle>
<fpcontent>A cadastral fabric (or parcel fabric) is a continuous surface of connected (map) parcels. Parcel polygons are defined by a series of boundary lines that store recorded dimensions as attributes in the lines table. Parcel polygons are also linked to each other by connection lines, for example, connection lines across roads. Because each and every parcel is either linked or connected, a seamless network of connected parcel boundaries, or cadastral fabric, is formed. Parcel lines have endpoints, which are the parcel corners. Parcel corner points are common between adjacent parcel boundaries, establishing connectivity and maintaining topological integrity in the network. In the geodatabase, topology is the arrangement that defines how point, line, and polygon features share coincident geometry. Spatial accuracy in the cadastral fabric is improved and maintained through adjustment by least squares. Control points are processed together with recorded dimensions to derive new, more accurate coordinates for parcel corners</fpcontent>
<fpimage>File:CFModel.gif</fpimage>
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<fpurl>Cadastral_fabric</fpurl></fp>[edit] Symbology
- <fp><fptitle>Symbology</fptitle>
<fpcontent>Symbology is defined in geographic information systems (GIS) as the set of conventions, rules, or encoding systems that define how geographic information is represented with symbols on a map. A characteristic of a map feature may influence the size, color, and shape of the symbol used. Generically, a symbol is something such as an object, picture, written word, sound, or particular mark that represents something else by association, resemblance, or convention. For example, a red octagon may be a symbol for ""STOP"". On maps, crossed sabres may indicate a battlefield. Numerals are symbols for numbers (amounts). All language consists of symbols. Personal names are symbols representing individuals. Maps typically include symbols that represent such features as streets, buildings, streams, and vegetation. Features are shown as points, lines, or areas, depending on their size and extent. Many features are shown by lines that may be straight, curved, solid, dashed, dotted, or in any combination.</fpcontent>
<fpimage>File:Symbology5.jpg</fpimage>
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<fpurl>Symbology</fpurl></fp>[edit] Roger Tomlinson
- <fp><fptitle>Roger Tomlinson</fptitle>
<fpcontent>Roger F. Tomlinson, CM (born 17 November 1933) is an English geographer and the primary originator of modern computerized Geographic Information Systems (GIS), and has been touted as the ""father of GIS"". Dr. Tomlinson is a native of Cambridge (England) and prior to attending university, he served in the Royal Air Force from 1951-54 as a pilot and flying officer. After his military service, Dr. Tomlinson attended the University of Nottingham and Acadia University for two separate undergraduate degrees in geography and geology respectively. He received a Masters degree in geography from McGill University where he specialized in the glacial geomorphology of Labrador. His Doctoral thesis at University College London was titled: The application of electronic computing methods and techniques to the storage, compilation, and assessment of mapped data. Dr. Tomlinson's early career included serving as an assistant professor at Acadia, working as the manager of the computer mapping division at Spartan Air Services in Ottawa, Ontario.</fpcontent>
<fpimage>File:Moll_-_A_new_map_of_the_whole_world_with_the_trade_winds.png</fpimage>
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<fpurl>Roger Tomlinson</fpurl></fp>[edit] Erwin Raisz
- <fp><fptitle>Erwin Raisz</fptitle>
<fpcontent>Erwin Josephus Raisz (1893-1968) was a distinguished, influential cartographer who helped pioneer and standardize the field of modern cartography in the 20th century with his 1938 publication of General Cartography (McGraw Hill), the first complete textbook on cartography written in English. Mr. Raisz was born in Hungary. As the son of a civil engineer, he was introduced to maps and their uses when his father took him on assignments in his youth. He was acclaimed for his unique artistic style, and in the course of his career created a substantial number of visually appealing hand-drawn maps and detailed geomorphological and landform sketches. Raisz received a degree in civil engineering and architecture from the Royal Polytechnicum in Budapest in 1914. After a brief term in the army he worked for an engineering firm before immigrating to the United States in 1923. He worked for the Ohman Map Company in New York City while attending graduate school at Columbia University.</fpcontent>
<fpimage>File:Raisz_model.gif</fpimage>
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<fpurl>Erwin_Raisz</fpurl></fp>[edit] Map projection
- <fp><fptitle>Map projection</fptitle>
<fpcontent>A map projection is any orderly system of parallels and meridians on which a map can be drawn.[1] Any mathematical function transforming coordinates from a curved surface to a plane is a projection. Since the Earth is roughly the shape of an oblate spheroid, map projections are necessary for creating maps of the Earth or parts of the Earth that are represented on a plane such as a piece of paper or a computer screen. In their attempt at planar representation of actual map features such as an island or continent on the curved surface of the earth, all map projections necessarily distort some aspects of these features. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore different map projections exist in order to preserve some properties of the spheroid-based features at the expense of other properties. A map projection is an essential component of any modern map, and there are an infinite number of possible map projections.</fpcontent>
<fpimage>File:Usgs_map_mercator.svg</fpimage>
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<fpurl>Map_projection</fpurl></fp>[edit] Education
- <fp><fptitle>Education</fptitle>
<fpcontent>A Geographic Information System (GIS) can be used effectively throughout several levels of formal and informal education. Robert Tinker, an educational researcher focused on using technology to teach math and science, advocated using GIS software to link students to global effects and concerns. Practitioners use GIS in academic instruction, educational administration, and in forming education policies. Use occurs at all levels beginning in primary and secondary grades, continuing to university level courses, throughout lifelong learning activities. GIS education occurs in both formal and informal learning settings. Students learn to use GIS in after-school programs, at 4-H clubs, as Girl- or Boy Scouts, and elsewhere. In more formal settings GIS is taught in schools, at technical colleges, universities, libraries, museums, arboreta, and other educational institutions. Teaching with GIS is emphasized at the elementary and secondary level where GIS is increasingly used to teach concepts and skills</fpcontent>
<fpimage>File:History_Woman_teaching_geometry.jpg</fpimage>
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<fpurl>Education</fpurl></fp>[edit] Jack D. Ives
- <fp><fptitle>Jack D. Ives</fptitle>
<fpcontent>Jack D. Ives, Professor, Ph.D. - Dr. Jack Ives is a graduate of University of Nottingham, UK (B.A. Geography, 1953) and McGill University, Canada (Ph.D. 1956), Dr. Ives emigrated to Canada with his wife Pauline in 1954. Dubbed the ""Father of Arctic and Alpine Geoecology"" by a former student, Dr. Ives is currently Professor of Geography and Environmental Studies at Carleton University of Canada. From the Himalayas to Baffin Island, mountains and Arctic regions have been the subject of fascination in Dr. Ives academic career for half a century. He has been incessantly working to ensure the long-term livability of the mountain environments to whom he fell in love when he was 15. He has abiding passion for the mountain environment and the peoples who have been living on them for centuries. His quest to conserve the world’s mountain ecosystems has taken on a particular urgency with recent times. Research Lab., Schefferville, and Assistant Professor at Department of Geography, McGill University (1957-1960).</fpcontent>
<fpimage>File:Jack-D-Ives.jpg</fpimage>
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<fpurl>Jack_D._Ives</fpurl></fp>[edit] Arthur H. Robinson
- <fp><fptitle>Arthur H. Robinson</fptitle>
<fpcontent>Arthur H. Robinson (January 5, 1915 – October 10, 2004) was an American geographer and cartographer, who was professor in the Geography Department at the University of Wisconsin in Madison from 1947 until he retired in 1980. He was a prolific writer and influential philosopher on cartography, and one of his most notable accomplishments is the Robinson projection in 1961. Arthur H. Robinson was born in Montreal, Quebec, Canada to American parents. He lived in Great Britain while he was young, and received his post-secondary education in the United States. His undergraduate work was done at Miami University in Oxford, Ohio, obtaining a B.A. degree in 1936. He demonstrated an aptitude for cartography and began drawing maps for faculty textbooks while earning a master's degree in geography from the University of Wisconsin-Madison in 1938, and he earned his Ph.D. degree from the Ohio State University in 1947. While at Ohio State University, Robinson worked to solve problems in the Map communication model.</fpcontent>
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<fpurl>Arthur_H._Robinson</fpurl></fp>[edit] Trilateration
- <fp><fptitle>Trilateration</fptitle>
<fpcontent>Trilateration is a method for determining the intersections of three sphere surfaces given the centers and radii of the three spheres. Trilateration is used by GPS devices to compute exact location based on signals received from a satellite and the time that signal takes to get from the satellite to the receiver. A mathematical derivation for the solution of a three-dimensional trilateration problem can be found by taking the formulae for three spheres and setting them equal to each other. To simplify the calculations, we apply three constraints to the centers of these spheres; we assume all three spheres are centered on the z=0 plane, one is at the origin, and one other is on the x-axis. It is possible to transform any set of three points to comply with these constraints, find the solution point, and then reverse the translation to find the solution point in the original coordinate system.</fpcontent>
<fpimage>File:Trilateration.png</fpimage>
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<fpurl>Trilateration</fpurl></fp>[edit] North American Datum
- <fp><fptitle>North American Datum</fptitle>
<fpcontent>The North American Datum is the official datum used for the primary geodetic network in North America. In the fields of cartography and land-use there are currently two North American Datums in use: the North American Datum of 1927 (NAD27) and the North American Datum of 1983 (NAD83). Both are geodetic reference systems, but each is based on different measurements. The North American Datum of 1927 (NAD27) is a datum based on the Clarke Ellipsoid of 1866. This Ellipsoid was created by way of manual surveying of the entire continent. The geodetic ""center"" of NAD27 is a base station at Meades Ranch in Kansas. Because Earth deviates significantly from a perfect ellipsoid, the ellipsoid that best approximates its shape varies region by region across the world. Clarke 1866, and North American Datum of 1927 with it, were surveyed to best suit North America as a whole. Likewise, historically most regions of the world used ellipsoids measured locally to best suit the vagaries of earth's shape in their respective locales.</fpcontent>
<fpimage>File:Triangulation_station_at_Meade%27s_Ranch.jpg</fpimage>
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<fpurl>North_American_Datum</fpurl></fp>[edit] Temporal GIS
- <fp><fptitle>Temporal GIS</fptitle>
<fpcontent>Temporal Geographic Information System (GIS) is an emerging capability in GIS for integrating temporal data with location and attribute data. Temporal data specifically refers to times or dates, enabling temporal visualization and ultimately temporal analysis. Temporal data may refer to discrete events, such as lightning strikes; moving objects, such as trains; or repeated observations, such as counts from traffic sensors.[1] Temporal changes occur at different points or periods of time and are recognized by changes in spatial properties and/or locations. A temporal GIS processes, manages, and analyzes spatio-temporal data; [2] spatial data that changes with time and is part of the geographic movement. The study of modeling temporal information in GIS started in the mid-1980s. The field of computer science's development of temporal data models influenced temporal modeling in the GIS field. Temporal modeling in computer sciences began with the integration of time with relational databases and later extended into object oriented modeling.</fpcontent>
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<fpurl>Temporal_GIS</fpurl></fp>[edit] Geotagging
- <fp><fptitle>Geotagging</fptitle>
<fpcontent>Geotagging is the process of adding geographical identification metadata to various media such as photographs, video, websites, or RSS feeds and is a form of geospatial metadata. These data usually consist of latitude and longitude coordinates, though they can also include altitude, bearing, accuracy data, and place names. Geotagging can help users find a wide variety of location-specific information. For instance, one can find images taken near a given location by entering latitude and longitude coordinates into a Geotagging-enabled image search engine. Geotagging-enabled information services can also potentially be used to find location-based news, websites, or other resources. Less commonly, this process has been called geocoding a term that more often refers to the process of taking non-coordinate based geographical identifiers, such as a street address, and finding associated geographic coordinates, or to the use of a camera that inserts the coordinates when making the picture, for example using its built-in GPS receiver.</fpcontent>
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<fpurl>Geotagging</fpurl></fp>[edit] Geomatics
- <fp><fptitle>Geomatics</fptitle>
<fpcontent>Geomatics is the science and technology of gathering, analyzing, interpreting, distributing and using geographic (or spatially referenced) information. Geomatics encompasses a broad range of disciplines: surveying, mapping, remote sensing, GIS and GPS.[1] Geomatics is fairly new, the term was apparently coined by B. Dubuisson in 1969. It includes the tools and techniques used in land surveying, remote sensing, Geographic Information Systems (GIS), Global Navigation Satellite Systems (GPS, GLONASS, GALILEO, COMPASS), photogrammetry, and related forms of earth mapping. Originally used in Canada, because the term is similar in French and English, geomatics has been adopted by the International Organization for Standardization, the Royal Institution of Chartered Surveyors, and many other international authorities, although some (especially in the United States) have shown a preference for the term technology. A good definition can be found on the University of Calgary's web page titled ""What is Geomatic Engineering?""</fpcontent>
<fpimage>File:RapidEye_Satellites.jpg</fpimage>
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<fpurl>Geomatics</fpurl></fp>
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