geographic information system gis redirects here for other uses see gis disambiguation system to capture manage and present geographic data a geographic information system gis is a system designed to capture store manipulate analyze manage and present spatial or geographic data gis applications are tools that allow users to create interactive queries usercreated searches analyze spatial information edit data in maps and present the results of all these operations gis can refer to a number of different technologies processes and methods it is attached to many operations and has many applications related to engineering planning management transportlogistics insurance telecommunications and business for that reason gis and location intelligence applications can be the foundation for many locationenabled services that rely on analysis and visualization gis can relate unrelated information by using location as the key index variable locations or extents in the earth spacetime may be recorded as datestimes of occurrence and x y and z coordinates representing longitude latitude and elevation respectively all earthbased spatialtemporal location and extent references should be relatable to one another and ultimately to a real physical location or extent this key characteristic of gis has begun to open new avenues of scientific inquiry history of development the first known use of the term geographic information system was by roger tomlinson in the year 1968 in his paper a geographic information system for regional planning e w gilberts version 1958 of john snows 1855map of the soho cholera outbreak showing the clusters of cholera cases in the london epidemic of 1854 previously one of the first applications of spatial analysis in epidemiology is the 1832 rapport sur la marche et les effets du cholra dans paris et le dpartement de la seine the french geographer charles picquet represented the 48districts of the city of paris by halftone color gradient according to the number of deaths by cholera per1000inhabitants in 1854 john snow determined the source of a cholera outbreak in london by marking points on a map depicting where the cholera victims lived and connecting the cluster that he found with a nearby water source this was one of the earliest successful uses of a geographic methodology in epidemiology while the basic elements of topography and theme existed previously in cartography the john snow map was unique using cartographic methods not only to depict but also to analyze clusters of geographically dependent phenomena the early20thcentury saw the development of photozincography which allowed maps to be split into layers for example one layer for vegetation and another for water this was particularly used for printing contours drawing these was a labourintensive task but having them on a separate layer meant they could be worked on without the other layers to confuse the draughtsman this work was originally drawn on glass plates but later plastic film was introduced with the advantages of being lighter using less storage space and being less brittle among others when all the layers were finished they were combined into one image using a large process camera once color printing came in the layers idea was also used for creating separate printing plates for each color while the use of layers much later became one of the main typical features of a contemporary gis the photographic process just described is not considered to be a gis in itself as the maps were just images with no database to link them to computer hardware development spurred by nuclear weapon research led to generalpurpose computer mapping applications by the early 1960s the year 1960 saw the development of the worlds first true operational gis in ottawa ontario canada by the federal department of forestry and rural development developed by dr roger tomlinson it was called the canada geographic information systemcgis and was used to store analyze and manipulate data collected for the canada land inventory an effort to determine the land capability for rural canada by mapping information about soils agriculture recreation wildlife waterfowl forestry and land use at a scale of 150000 a rating classification factor was also added to permit analysis cgis was an improvement over computer mapping applications as it provided capabilities for overlay measurement and digitizingscanning it supported a national coordinate system that spanned the continent coded lines as arcs having a true embedded topology and it stored the attribute and locational information in separate files as a result of this tomlinson has become known as the father of gis particularly for his use of overlays in promoting the spatial analysis of convergent geographic data cgis lasted into the 1990s and built a large digital land resource database in canada it was developed as a mainframebased system in support of federal and provincial resource planning and management its strength was continentwide analysis of complex datasets the cgis was never available commercially in1964 howard t fisher formed the laboratory for computer graphics and spatial analysis at the harvard graduate school of design lcgsa 19651991 where a number of important theoretical concepts in spatial data handling were developed and which by the 1970s had distributed seminal software code and systems such as symap grid and odyssey that served as sources for subsequent commercial developmentto universities research centers and corporations worldwide by the late 1970s two public domain gis systems moss and grass gis were in development and by the early 1980s ms computing later intergraph along with bentley systems incorporated for the cadplatform environmental systems research institute esri cariscomputer aided resource information system mapinfo corporation and erdasearth resource data analysis system emerged as commercial vendors of gissoftware successfully incorporating many of the cgisfeatures combining the first generation approach to separation of spatial and attribute information with a second generation approach to organizing attribute data into database structures in 1986 mapping display and analysis system midas the first desktop gis product was released for the dos operating system this was renamed in 1990 to mapinfo for windows when it was ported to the microsoft windows platform this began the process of moving gis from the research department into the business environment by the end of the 20thcentury the rapid growth in various systems had been consolidated and standardized on relatively few platforms and users were beginning to explore viewing gisdata over the internet requiring data format and transfer standards more recently a growing number of free opensource gis packages run on a range of operating systems and can be customized to perform specific tasks increasingly geospatial data and mapping applications are being made available via the world wide web see list of gis software gis as a service several articles on the history of gis have been published techniques and technology modern gis technologies use digital information for which various digitized data creation methods are used the most common method of data creation is digitization where a hard copy map or survey plan is transferred into a digital medium through the use of a cad program and georeferencing capabilities with the wide availability of orthorectified imagery from satellites aircraft helikites and uavs headsup digitizing is becoming the main avenue through which geographic data is extracted headsup digitizing involves the tracing of geographic data directly on top of the aerial imagery instead of by the traditional method of tracing the geographic form on a separate digitizing tablet headsdown digitizing relating information from different sources gis uses spatiotemporal spacetime location as the key index variable for all other information just as a relational database containing text or numbers can relate many different tables using common key index variables gis can relate otherwise unrelated information by using location as the key index variable the key is the location andor extent in spacetime any variable that can be located spatially and increasingly also temporally can be referenced using a gis locations or extents in earth spacetime may be recorded as datestimes of occurrence and x y and z coordinates representing longitude latitude and elevation respectively these gis coordinates may represent other quantified systems of temporospatial reference for example film frame number stream gage station highway milemarker surveyor benchmark building address street intersection entrance gate water depth sounding pos or cad drawing originunits units applied to recorded temporalspatial data can vary widely even when using exactly the same data see map projections but all earthbased spatialtemporal location and extent references should ideally be relatable to one another and ultimately to a real physical location or extent in spacetime related by accurate spatial information an incredible variety of realworld and projected past or future data can be analyzed interpreted and represented this key characteristic of gis has begun to open new avenues of scientific inquiry into behaviors and patterns of realworld information that previously had not been systematically correlated gis uncertainties gis accuracy depends upon source data and how it is encoded to be data referenced land surveyors have been able to provide a high level of positional accuracy utilizing the gpsderived positions powerful computers and web technology are changing the quality utility and expectations of gis to serve society on a grand scale but nevertheless there are other source data that affect overall gis accuracy like paper maps though these may be of limited use in achieving the desired accuracy in developing a digital topographic database for a gis topographical maps are the main source and aerial photography and satellite imagery are extra sources for collecting data and identifying attributes which can be mapped in layers over a location facsimile of scale the scale of a map and geographical rendering area representation type are very important aspects since the information content depends mainly on the scale set and resulting locatability of the maps representations in order to digitize a map the map has to be checked within theoretical dimensions then scanned into a raster format and resulting raster data has to be given a theoretical dimension by a rubber sheetingwarping technology process a quantitative analysis of maps brings accuracy issues into focus the electronic and other equipment used to make measurements for gis is far more precise than the machines of conventional map analysis all geographical data are inherently inaccurate and these inaccuracies will propagate through gisoperations in ways that are difficult to predict data representation gis file formats gis data represents real objects such as roads land use elevation trees waterways etc with digital data determining the mix real objects can be divided into two abstractions discrete objects eg a house and continuous fields such as rainfall amount or elevations traditionally there are two broad methods used to store data in a gis for both kinds of abstractions mapping references raster images and vector points lines and polygons are the stuff of mapped location attribute references a new hybrid method of storing data is that of identifying point clouds which combine threedimensional points with rgb information at each point returning a 3d color image gis thematic maps then are becoming more and more realistically visually descriptive of what they set out to show or determine for a list of popular gis file formats such as shapefiles see gis file formats popular gis file formats data capture example of hardware for mapping gps and laser rangefinder and data collection rugged computer the current trend for geographical information system gis is that accurate mapping and data analysis are completed while in the field depicted hardware fieldmap technology is used mainly for forest inventories monitoring and mapping data captureentering information into the systemconsumes much of the time of gispractitioners there are a variety of methods used to enter data into a gis where it is stored in a digital format existing data printed on paper or pet film maps can be digitized or scanned to produce digital data a digitizer produces vector data as an operator traces points lines and polygon boundaries from a map scanning a map results in raster data that could be further processed to produce vector data survey data can be directly entered into a gis from digital data collection systems on survey instruments using a technique called coordinate geometry cogo positions from a global navigation satellite system gnss like global positioning system can also be collected and then imported into a gis a current trend in data collection gives users the ability to utilize field computers with the ability to edit live data using wireless connections or disconnected editing sessions this has been enhanced by the availability of lowcost mappinggrade gps units with decimeter accuracy in real time this eliminates the need to post process import and update the data in the office after fieldwork has been collected this includes the ability to incorporate positions collected using a laser rangefinder new technologies also allow users to create maps as well as analysis directly in the field making projects more efficient and mapping more accurate remotely sensed data also plays an important role in data collection and consist of sensors attached to a platform sensors include cameras digital scanners and lidar while platforms usually consist of aircraft and satellites in england in the mid 1990s hybrid kiteballoons called helikites first pioneered the use of compact airborne digital cameras as airborne geoinformation systems aircraft measurement software accurate to 04mm was used to link the photographs and measure the ground helikites are inexpensive and gather more accurate data than aircraft helikites can be used over roads railways and towns where unmanned aerial vehicles uavs are banned recently aerial data collection is becoming possible with miniature uavs for example the aeryon scout was used to map a 50acrearea with a ground sample distance of 1 inch 254cm in only 12minutes the majority of digital data currently comes from photo interpretation of aerial photographs softcopy workstations are used to digitize features directly from stereo pairs of digital photographs these systems allow data to be captured in two and three dimensions with elevations measured directly from a stereo pair using principles of photogrammetry analog aerial photos must be scanned before being entered into a softcopy system for highquality digital cameras this step is skipped satellite remote sensing provides another important source of spatial data here satellites use different sensor packages to passively measure the reflectance from parts of the electromagnetic spectrum or radio waves that were sent out from an active sensor such as radar remote sensing collects raster data that can be further processed using different bands to identify objects and classes of interest such as land cover when data is captured the user should consider if the data should be captured with either a relative accuracy or absolute accuracy since this could not only influence how information will be interpreted but also the cost of data capture after entering data into a gis the data usually requires editing to remove errors or further processing for vector data it must be made topologically correct before it can be used for some advanced analysis for example in a road network lines must connect with nodes at an intersection errors such as undershoots and overshoots must also be removed for scanned maps blemishes on the source map may need to be removed from the resulting raster for example a fleck of dirt might connect two lines that should not be connected rastertovector translation data restructuring can be performed by a gis to convert data into different formats for example a gis may be used to convert a satellite image map to a vector structure by generating lines around all cells with the same classification while determining the cell spatial relationships such as adjacency or inclusion more advanced data processing can occur with image processing a technique developed in the late1960s by nasa and the private sector to provide contrast enhancement false color rendering and a variety of other techniques including use of two dimensional fourier transforms since digital data is collected and stored in various ways the two data sources may not be entirely compatible so a gis must be able to convert geographic data from one structure to another in so doing the implicit assumptions behind different ontologies and classifications require analysis object ontologies have gained increasing prominence as a consequence of objectoriented programming and sustained work by barry smith and coworkers projections coordinate systems and registration map projection the earth can be represented by various models each of which may provide a different set of coordinates eg latitude longitude elevation for any given point on the earths surface the simplest model is to assume the earth is a perfect sphere as more measurements of the earth have accumulated the models of the earth have become more sophisticated and more accurate in fact there are models called datums that apply to different areas of the earth to provide increased accuracy like nad83 for us measurements and the world geodetic system for worldwide measurements spatial analysis with geographical information system gis further information spatial analysis gis spatial analysis is a rapidly changing field and gis packages are increasingly including analytical tools as standard builtin facilities as optional toolsets as addins or analysts in many instances these are provided by the original software suppliers commercial vendors or collaborative non commercial development teams while in other cases facilities have been developed and are provided by third parties furthermore many products offer software development kits sdks programming languages and language support scripting facilities andor special interfaces for developing ones own analytical tools or variants the increased availability has created a new dimension to business intelligence termed spatial intelligence which when openly delivered via intranet democratizes access to geographic and social network data geospatial intelligence based on gis spatial analysis has also become a key element for security gis as a whole can be described as conversion to a vectorial representation or to any other digitisation process slope and aspect slope can be defined as the steepness or gradient of a unit of terrain usually measured as an angle in degrees or as a percentage aspect can be defined as the direction in which a unit of terrain faces aspect is usually expressed in degrees from north slope aspect and surface curvature in terrain analysis are all derived from neighborhood operations using elevation values of a cells adjacent neighbours the following method can be used to derive slope and aspect the elevation at a point or unit of terrain will have perpendicular tangents slope passing through the point in an eastwest and northsouth direction these two tangents give two components zx and zy which then be used to determine the overall direction of slope and the aspect of the slope the gradient is defined as a vector quantity with components equal to the partial derivatives of the surface in the x and y directions the calculation of the overall 3x3 grid slope s and aspect a for methods that determine eastwest and northsouth component use the following formulas respectively tan s z x 2 z y 2 displaystyle tan ssqrt leftfrac partial zpartial xright2leftfrac partial zpartial yright2 tan a z y z x displaystyle tan aleftfrac leftfrac partial zpartial yrightleftfrac partial zpartial xrightright zhou and liu describe another formula for calculating aspect as follows a 270 arctan z x z y 90 z y z y displaystyle a270circ arctan leftfrac leftfrac partial zpartial xrightleftfrac partial zpartial yrightright90circ leftfrac leftfrac partial zpartial yrightleftfrac partial zpartial yrightright data analysis it is difficult to relate wetlands maps to rainfall amounts recorded at different points such as airports television stations and schools a gis however can be used to depict two and threedimensional characteristics of the earths surface subsurface and atmosphere from information points for example a gis can quickly generate a map with isopleth or contour lines that indicate differing amounts of rainfall such a map can be thought of as a rainfall contour map many sophisticated methods can estimate the characteristics of surfaces from a limited number of point measurements a twodimensional contour map created from the surface modeling of rainfall point measurements may be overlaid and analyzed with any other map in a gis covering the same area this gis derived map can then provide additional information such as the viability of water power potential as a renewable energy source similarly gis can be used to compare other renewable energy resources to find the best geographic potential for a region additionally from a series of threedimensional points or digital elevation model isopleth lines representing elevation contours can be generated along with slope analysis shaded relief and other elevation products watersheds can be easily defined for any given reach by computing all of the areas contiguous and uphill from any given point of interest similarly an expected thalweg of where surface water would want to travel in intermittent and permanent streams can be computed from elevation data in the gis topological modeling a gis can recognize and analyze the spatial relationships that exist within digitally stored spatial data these topological relationships allow complex spatial modelling and analysis to be performed topological relationships between geometric entities traditionally include adjacency what adjoins what containment what encloses what and proximity how close something is to something else geometric networks geometric networks are linear networks of objects that can be used to represent interconnected features and to perform special spatial analysis on them a geometric network is composed of edges which are connected at junction points similar to graphs in mathematics and computer science just like graphs networks can have weight and flow assigned to its edges which can be used to represent various interconnected features more accurately geometric networks are often used to model road networks and public utility networks such as electric gas and water networks network modeling is also commonly employed in transportation planning hydrology modeling and infrastructure modeling hydrological modeling gis hydrological models can provide a spatial element that other hydrological models lack with the analysis of variables such as slope aspect and watershed or catchment area more detail can be added to the model such as terrain roughness vegetation types and soil types which can influence infiltration and evapotranspiration rates and hence influencing surface flow one of the main uses of hydrological modeling is in environmental contamination research other applications of hydrological modeling include groundwater and surface water mapping as well as flood risk maps cartographic modeling an example of use of layers in a gis application in this example the forestcover layer light green forms the bottom layer with the topographic layer contour lines over it next up is a standing water layer pond lake and then a flowing water layer stream river followed by the boundary layer and finally the road layer on top the order is very important in order to properly display the final result note that the ponds are layered under the streams so that a stream line can be seen overlying one of the ponds dana tomlin probably coined the term cartographic modeling in his phd dissertation 1983 he later used it in the title of his book geographic information systems and cartographic modeling 1990 cartographic modeling refers to a process where several thematic layers of the same area are produced processed and analyzed tomlin used raster layers but the overlay method see below can be used more generally operations on map layers can be combined into algorithms and eventually into simulation or optimization models map overlay the combination of several spatial datasets points lines or polygons creates a new output vector dataset visually similar to stacking several maps of the same region these overlays are similar to mathematical venn diagram overlays a union overlay combines the geographic features and attribute tables of both inputs into a single new output an intersect overlay defines the area where both inputs overlap and retains a set of attribute fields for each a symmetric difference overlay defines an output area that includes the total area of both inputs except for the overlapping area data extraction is a gis process similar to vector overlay though it can be used in either vector or raster data analysis rather than combining the properties and features of both datasets data extraction involves using a clip or mask to extract the features of one data set that fall within the spatial extent of another dataset in raster data analysis the overlay of datasets is accomplished through a process known as local operation on multiple rasters or map algebra through a function that combines the values of each rasters matrix this function may weigh some inputs more than others through use of an index model that reflects the influence of various factors upon a geographic phenomenon geostatistics geostatistics geostatistics is a branch of statistics that deals with field data spatial data with a continuous index it provides methods to model spatial correlation and predict values at arbitrary locations interpolation when phenomena are measured the observation methods dictate the accuracy of any subsequent analysis due to the nature of the data eg traffic patterns in an urban environment weather patterns over the pacific ocean a constant or dynamic degree of precision is always lost in the measurement this loss of precision is determined from the scale and distribution of the data collection to determine the statistical relevance of the analysis an average is determined so that points gradients outside of any immediate measurement can be included to determine their predicted behavior this is due to the limitations of the applied statistic and data collection methods and interpolation is required to predict the behavior of particles points and locations that are not directly measurable hillshade model derived from a digital elevation model of the valestra area in the northern apennines italyinterpolation is the process by which a surface is created usually a raster dataset through the input of data collected at a number of sample points there are several forms of interpolation each which treats the data differently depending on the properties of the data set in comparing interpolation methods the first consideration should be whether or not the source data will change exact or approximate next is whether the method is subjective a human interpretation or objective then there is the nature of transitions between points are they abrupt or gradual finally there is whether a method is global it uses the entire data set to form the model or local where an algorithm is repeated for a small section of terrain interpolation is a justified measurement because of a spatial autocorrelation principle that recognizes that data collected at any position will have a great similarity to or influence of those locations within its immediate vicinity digital elevation models triangulated irregular networks edgefinding algorithms thiessen polygons fourier analysis weighted moving averages inverse distance weighting kriging spline and trend surface analysis are all mathematical methods to produce interpolative data address geocoding geocoding geocoding is interpolating spatial locations xy coordinates from street addresses or any other spatially referenced data such as zipcodes parcel lots and address locations a reference theme is required to geocode individual addresses such as a road centerline file with address ranges the individual address locations have historically been interpolated or estimated by examining address ranges along a road segment these are usually provided in the form of a table or database the software will then place a dot approximately where that address belongs along the segment of centerline for example an address point of 500 will be at the midpoint of a line segment that starts with address1 and ends with address1000 geocoding can also be applied against actual parcel data typically from municipal tax maps in this case the result of the geocoding will be an actually positioned space as opposed to an interpolated point this approach is being increasingly used to provide more precise location information reverse geocoding reverse geocoding is the process of returning an estimated street address number as it relates to a given coordinate for example a user can click on a road centerline theme thus providing a coordinate and have information returned that reflects the estimated house number this house number is interpolated from a range assigned to that road segment if the user clicks at the midpoint of a segment that starts with address1 and ends with100 the returned value will be somewhere near 50 note that reverse geocoding does not return actual addresses only estimates of what should be there based on the predetermined range multicriteria decision analysis coupled with gis multicriteria decision analysis methods support decisionmakers in analysing a set of alternative spatial solutions such as the most likely ecological habitat for restoration against multiple criteria such as vegetation cover or roads mcda uses decision rules to aggregate the criteria which allows the alternative solutions to be ranked or prioritised gis mcda may reduce costs and time involved in identifying potential restoration sites data output and cartography cartography is the design and production of maps or visual representations of spatial data the vast majority of modern cartography is done with the help of computers usually using gis but production of quality cartography is also achieved by importing layers into a design program to refine it most gissoftware gives the user substantial control over the appearance of the data cartographic work serves two major functions first it produces graphics on the screen or on paper that convey the results of analysis to the people who make decisions about resources wall maps and other graphics can be generated allowing the viewer to visualize and thereby understand the results of analyses or simulations of potential events web map servers facilitate distribution of generated maps through web browsers using various implementations of webbased application programming interfaces ajax java flash etc second other database information can be generated for further analysis or use an example would be a list of all addresses within onemile 16km of a toxic spill graphic display techniques traditional maps are abstractions of the real world a sampling of important elements portrayed on a sheet of paper with symbols to represent physical objects people who use maps must interpret these symbols topographic maps show the shape of land surface with contour lines or with shaded relief today graphic display techniques such as shading based on altitude in a gis can make relationships among map elements visible heightening ones ability to extract and analyze information for example two types of data were combined in a gis to produce a perspective view of a portion of sanmateo county california the digital elevation model consisting of surface elevations recorded on a 30meter horizontal grid shows high elevations as white and low elevation as black the accompanying landsat thematic mapper image shows a falsecolor infrared image looking down at the same area in 30meterpixels or picture elements for the same coordinate points pixelbypixel as the elevation information a gis was used to register and combine the two images to render the threedimensional perspective view looking down the san andreas fault using the thematic mapper image pixels but shaded using the elevation of the landforms the gisdisplay depends on the viewing point of the observer and time of day of the display to properly render the shadows created by the suns rays at that latitude longitude and time of day an archeochrome is a new way of displaying spatial data it is a thematic on a 3dmap that is applied to a specific building or a part of a building it is suited to the visual display of heatloss data spatial etl spatial etl tools provide the data processing functionality of traditional extract transform loadetl software but with a primary focus on the ability to manage spatial data they provide gisusers with the ability to translate data between different standards and proprietary formats whilst geometrically transforming the data en route these tools can come in the form of addins to existing widerpurpose software such as spreadsheets gis data mining gis or spatial data mining is the application of data mining methods to spatial data data mining which is the partially automated search for hidden patterns in large databases offers great potential benefits for applied gisbaseddecisionmaking typical applications include environmental monitoring a characteristic of such applications is that spatial correlation between data measurements require the use of specialized algorithms for more efficient data analysis applications the implementation of a gis is often driven by jurisdictional such as a city purpose or application requirements generally a gis implementation may be customdesigned for an organization hence a gis deployment developed for an application jurisdiction enterprise or purpose may not be necessarily interoperable or compatible with a gis that has been developed for some other application jurisdiction enterprise or purpose gis provides for every kind of locationbased organization a platform to update geographical data without wasting time to visit the field and update a database manually gis when integrated with other powerful enterprise solutions like sap geabios tiny wmswfs client flashdhtml many disciplines can benefit from gistechnology an active gismarket has resulted in lower costs and continual improvements in the hardware and software components of gis and usage in the fields of science government business and industry with applications including real estate public health crime mapping national defense sustainable development natural resources climatology landscape architecture archaeology regional and community planning transportation and logistics gis is also diverging into locationbased services which allows gpsenabled mobile devices to display their location in relation to fixed objects nearest restaurant gas station fire hydrant or mobile objects friends children policecar or to relay their position back to a central server for display or other processing open geospatial consortium standards open geospatial consortium the open geospatial consortium ogc is an international industry consortium of 384companies government agencies universities and individuals participating in a consensus process to develop publicly available geoprocessing specifications open interfaces and protocols defined by opengisspecifications support interoperable solutions that geoenable the web wireless and locationbased services and mainstreamit and empower technology developers to make complex spatial information and services accessible and useful with all kinds of applications open geospatial consortium protocols include web map service and web feature service gisproducts are broken down by theogc into two categories based on how completely and accurately the software follows the ogcspecifications ogc standards help gis tools communicate compliant products are software products that comply to ogcsopengisspecifications when a product has been tested and certified as compliant through the ogctesting program the product is automatically registered as compliant on this site implementing products are software products that implement opengisspecifications but have not yet passed a compliance test compliance tests are not available for all specifications developers can register their products as implementing draft or approved specifications though ogcreserves the right to review and verify each entry web mapping web mapping in recent years there has been a proliferation of freetouse and easily accessible mapping software such as the proprietary web applications googlemaps and bingmaps as well as the free and opensource alternative openstreetmap these services give the public access to huge amounts of geographic data perceived by many users to be as trustworthy and usable as professional information some of them like google maps and openlayers expose an application programming interface api that enable users to create custom applications these toolkits commonly offer street maps aerialsatellite imagery geocoding searches and routing functionality web mapping has also uncovered the potential of crowdsourcing geodata in projects like openstreetmap which is a collaborative project to create a free editable map of the world these mashup projects have been proven to provide a high level of value and benefit to end users outside that possible through traditional geographic information adding the dimension of time see also historical geographic information system and time geography the condition of the earths surface atmosphere and subsurface can be examined by feeding satellite data into a gis gistechnology gives researchers the ability to examine the variations in earth processes over days months and years as an example the changes in vegetation vigor through a growing season can be animated to determine when drought was most extensive in a particular region the resulting graphic represents a rough measure of plant health working with two variables over time would then allow researchers to detect regional differences in the lag between a decline in rainfall and its effect on vegetation gistechnology and the availability of digital data on regional and global scales enable such analyses the satellite sensor output used to generate a vegetation graphic is produced for example by the advanced veryhighresolution radiometer avhrr this sensor system detects the amounts of energy reflected from the earths surface across various bands of the spectrum for surface areas of about 1 square kilometer the satellite sensor produces images of a particular location on the earth twice a day avhrr and more recently the moderateresolution imaging spectroradiometer modis are only two of many sensor systems used for earth surface analysis in addition to the integration of time in environmental studies gis is also being explored for its ability to track and model the progress of humans throughout their daily routines a concrete example of progress in this area is the recent release of timespecific population data by the uscensus in this data set the populations of cities are shown for daytime and evening hours highlighting the pattern of concentration and dispersion generated by north american commuting patterns the manipulation and generation of data required to produce this data would not have been possible withoutgis using models to project the data held by a gisforward in time have enabled planners to test policy decisions using spatial decision support systems semantics tools and technologies emerging from the world wide web consortiums semantic web are proving useful for data integration problems in information systems correspondingly such technologies have been proposed as a means to facilitate interoperability and data reuse among gisapplications ontologies are a key component of this semantic approach as they allow a formal machinereadable specification of the concepts and relationships in a given domain this in turn allows a gis to focus on the intended meaning of data rather than its syntax or structure for example reasoning that a land cover type classified as deciduous needleleaf trees in one dataset is a specialization or subset of land cover type forest in another more roughly classified dataset can help a gis automatically merge the two datasets under the more general land cover classification tentative ontologies have been developed in areas related to gisapplications for example the hydrology ontology to represent geospatial data on the web geosparql is a standard developed by the ordnance survey united states geological survey natural resources canada australias commonwealth scientific and industrial research organisation and others to support ontology creation and reasoning using wellunderstood ogc literals gml wkt topological relationships simple features rcc8 de9im rdf and the sparql database query protocols recent research results in this area can be seen in the international conference on geospatial semantics workshop at the international semantic web conference implications of gis in society neogeography and public participation gis with the popularization of gis in decision making scholars have begun to scrutinize the social and political implications of gis other related topics include discussion on copyright privacy and censorship a more optimistic social approach to gisadoption is to use it as a tool for public participation gis in education see also esri education user conference at the end of the 20th century gis began to be recognized as tools that could be used in the classroom36 gis seem to provide many advantages in teaching geography because they allow for analyses based on real geographic data and also help raise many research questions from teachers and students in classrooms as well as they contribute to improvement in learning by developing spatial and geographical thinking and in many cases student motivation38 gis in local government gis is proven as an organizationwide enterprise and enduring technology that continues to change how local government operates government agencies have adopted gis technology as a method to better manage the following areas of government organization economic development departments use interactive gis mapping tools aggregated with other data demographics labor force business industry talent along with a database of available commercial sites and buildings in order to attract investment and support existing business businesses making location decisions can use the tools to choose communities and sites that best match their criteria for success gis plannings zoomprospector enterprise an intelligence components software is the industry leader servicing more than 60 of the us population more than 30 of canadians and locations in the uk and switzerland you can see an example of these tools here on the state of pennsylvanias department of community and economic development website pasitesearchcom public safety operations such as emergency operations centers fire prevention police and sheriff mobile technology and dispatch and mapping weather risks parks and recreation departments and their functions in asset inventory land conservation land management and cemetery management public works and utilities tracking water and stormwater drainage electrical assets engineering projects and public transportation assets and trends fiber network management for interdepartmental network assets school analytical and demographic data asset management and improvementexpansion planning public administration for election data property records and zoningmanagement the open data initiative is pushing local government to take advantage of technology such as gis technology as it encompasses the requirements to fit the open dataopen government model of transparency the push for open data within government organizations is driving the growth in local government gis technology spending and database management atlas portal amfmgis arcgis atlocation mapping automotive navigation system collaborative mapping comparison of gis software countermapping cybergis digital geologic mapping distributed gis geographic information systems in china geographic information systems in geospatial intelligence geomatics gis and aquatic science gis and public health giscorps gis day gis in archaeology grass gis gvsig historical gis integrated geo systems list of gis data sources list of gis software map database management participatory gis qgis saga gis traditional knowledge gis virtual globe berry j k 1993 beyond mapping concepts algorithms and issues in gis fort collins co gis world books bolstad p 2005 gis fundamentals a first text on geographic information systems second edition white bear lake mn eider press 543 pp burrough p a and mcdonnell r a 1998 principles of geographical information systems oxford university press oxford 327 pp buzai gd robinson d 2010 geographical information systems in latin america 19872010 a preliminary overview journal of latin american geography 9 3 931 doi101353lag20100027 chang k 2007 introduction to geographic information system 4th edition mcgraw hill isbn9780071267588 de smith mj goodchild mf longley pa 2007 geospatial analysis a comprehensive guide to principles techniques and software tools 2nd ed troubador uk isbn9781848761582 elangovank 2006gis fundamentals applications and implementations new india publishing agency new delhi208 pp fu p and j sun 2010 web gis principles and applications esri press redlands ca isbn158948245x harvey francis2008 a primer of gis fundamental geographic and cartographic concepts the guilford press 31 pp heywood i cornelius s and carver s 2006 an introduction to geographical information systems prentice hall 3rd edition longley pa goodchild mf maguire dj and rhind dw 2005 geographic information systems and science chichester wiley 2nd edition maguire dj goodchild mf rhind dw 1997 geographic information systems principles and applications longman scientific and technical harlow maliene v grigonis v paleviius v griffiths s 2011 geographic information system old principles with new capabilities urban design international 16 1 16 doi101057udi201025 mennecke brian e lawrence a west jr october 2001 geographic information systems in developing countries issues in data collection implementation and management journal of global information management 9 4 4555 ott t and swiaczny f 2001 timeintegrative gis management and analysis of spatiotemporal data berlin heidelberg new york springer sajeevan g march 2008 latitude and longitude a misunderstanding pdf current science 94 5 568 sajeevan g 2006 customise and empower geospatial today 4 7 4043 thurston j poiker tk and j patrick moore 2003 integrated geospatial technologies a guide to gps gis and data logging hoboken new jersey wiley tomlinson rf 2005 thinking about gis geographic information system planning for managers esri press 328 pp wise s 2002 gis basics london taylor francis worboys michael duckham matt 2004 gis a computing perspective boca raton crc press isbn0415283752 wheatley david and gillings mark 2002 spatial technology and archaeology the archaeological application of gis london new york taylor francis holdstock david 2017 strategic gis planning and management in local government boca raton fl crc press isbn9781466556508 media related to geographic information systems at wikimedia commons vtegeography topics history index outline brancheshuman agricultural behavioral cultural development economic health historical political population settlement regional urban physical biogeography ecology phytogeography zoogeography coastal oceanography earth science atmospheric science meteorology environmental science climatology paleoclimatology palaeogeography geobiology geophysics geodesy earth system science geomorphology geology glaciology hydrology limnology pedology edaphologysoil science quaternary science integrated integrated environmental environmental social science environmental studies landscape 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