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Geospatial

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Encyclopedia
Geospatial analysis is an approach to applying statistical analysis and other informational techniques to geographically based data. Such analysis employs spatial software and analytical
Scientific modelling
Scientific modelling is the process of generating abstract, conceptual, graphical and/or mathematical models. Science offers a growing collection of methods, techniques and theory about all kinds of specialized scientific modelling...

 methods with terrestrial or geographic datasets, including geographic information system
Geographic Information System
A geographic information system, geographical information science, or geospatial information studies is a system designed to capture, store, manipulate, analyze, manage, and present all types of geographically referenced data...

s and geomatics
Geomatics
Geomatics is the discipline of gathering, storing, processing, and delivering geographic information, or spatially referenced information.-Overview and etymology:...

.

Geographical information system usage


Geographical information systems (GIS) use geospatial analysis in a variety of contexts.

Basic applications


Geospatial analysis, using GIS, was developed for problems in the environmental and life sciences, in particular ecology, geology and epidemiology. It has extended to almost all industries including defense, intelligence, utilities, Natural Resources (i.e. Oil and Gas, Forestry etc), social sciences, medicine and Public Safety (i.e. emergency management and criminology). Spatial statistics typically result primarily from observation rather than experimentation.

Basic operations


In the case of vector-based GIS this typically means operations such as map overlay (combining two or more maps or map layers according to predefined rules), simple buffering (identifying regions of a map within a specified distance of one or more features, such as towns, roads or rivers) and similar basic operations. This reflects (and is reflected in) the use of the term spatial analysis within the Open Geospatial Consortium (OGC
OGC
OGC may refer to:* Oculogyric crisis, a dystonic reaction to certain drugs and/or medical conditions* Office of Government Commerce, a department of the government of the United Kingdom...

) “simple feature specifications”. For raster-based GIS, widely used in the environmental sciences and remote sensing, this typically means a range of actions applied to the grid cells of one or more maps (or images) often involving filtering and/or algebraic operations (map algebra). These techniques involve processing one or more raster layers according to simple rules resulting in a new map layer, for example replacing each cell value with some combination of its neighbours’ values, or computing the sum or difference of specific attribute values for each grid cell in two matching raster datasets. Descriptive statistics, such as cell counts, means, variances, maxima, minima, cumulative values, frequencies and a number of other measures and distance computations are also often included in this generic term spatial analysis
Spatial analysis
Spatial analysis or spatial statistics includes any of the formal techniques which study entities using their topological, geometric, or geographic properties...

. Spatial analysis includes a large variety of statistical techniques (descriptive, exploratory
Exploratory data analysis
In statistics, exploratory data analysis is an approach to analysing data sets to summarize their main characteristics in easy-to-understand form, often with visual graphs, without using a statistical model or having formulated a hypothesis...

, and explanatory statistics
Statistics
Statistics is the study of the collection, organization, analysis, and interpretation of data. It deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments....

) that apply to data that vary spatially and which can vary over time.

Advanced operations


Geospatial analysis goes beyond 2D mapping operations and spatial statistics. It includes:
  • Surface analysis —in particular analysing the properties of physical surfaces, such as gradient
    Gradient
    In vector calculus, the gradient of a scalar field is a vector field that points in the direction of the greatest rate of increase of the scalar field, and whose magnitude is the greatest rate of change....

    , aspect
    Aspect
    Aspect may be:*Aspect , a feature that is linked to many parts of a program, but which is not necessarily the primary function of the program...

     and visibility
    Visibility
    In meteorology, visibility is a measure of the distance at which an object or light can be clearly discerned. It is reported within surface weather observations and METAR code either in meters or statute miles, depending upon the country. Visibility affects all forms of traffic: roads, sailing...

    , and analysing surface-like data “fields”;
  • Network analysis
    Network analysis
    Network analysis can refer to:* Analysis of general networks: see Network theory.* Electrical network analysis see Network analysis .* Social network analysis.You may also be interested in Network planning and design...

     — examining the properties of natural and man-made networks in order to understand the behaviour of flows within and around such networks; and locational analysis. GIS-based network analysis may be used to address a wide range of practical problems such as route selection and facility location (core topics in the field of operations research
    Operations research
    Operations research is an interdisciplinary mathematical science that focuses on the effective use of technology by organizations...

    , and problems involving flows such as those found in hydrology
    Hydrology
    Hydrology is the study of the movement, distribution, and quality of water on Earth and other planets, including the hydrologic cycle, water resources and environmental watershed sustainability...

     and transportation research. In many instances location problems relate to networks and as such are addressed with tools designed for this purpose, but in others existing networks may have little or no relevance or may be impractical to incorporate within the modeling process. Problems that are not specifically network constrained, such as new road or pipeline routing, regional warehouse location, mobile phone mast positioning or the selection of rural community health care sites, may be effectively analysed (at least initially) without reference to existing physical networks. Locational analysis "in the plane" is also applicable where suitable network datasets are not available, or are too large or expensive to be utilised, or where the location algorithm is very complex or involves the examination or simulation of a very large number of alternative configurations.
  • Geovisualization
    Geovisualization
    Geovisualization, short for Geographic Visualization, refers to a set of tools and techniques supporting geospatial data analysis through the use of interactive visualization....

     — the creation and manipulation of images, maps, diagrams, charts, 3D views and their associated tabular datasets. GIS packages increasingly provide a range of such tools, providing static or rotating views, draping images over 2.5D surface representations, providing animations and fly-throughs, dynamic linking and brushing and spatio-temporal visualisations. This latter class of tools is the least developed, reflecting in part the limited range of suitable compatible datasets and the limited set of analytical methods available, although this picture is changing rapidly. All these facilities augment the core tools utilised in spatial analysis throughout the analytical process (exploration of data, identification of patterns and relationships, construction of models, and communication of results)

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