Geospatial
From Wikipedia, the free encyclopedia
[edit] Overview
Geospatial is a term widely used to describe the combination of spatial software and analytical methods with terrestrial or geographic datasets. The term is often used in conjunction with geographic information systems and geomatics.
Many GIS products apply the term geospatial analysis in a very narrow context. 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) “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.
However, the above list of functions cover only the most basic of facilities, albeit those that may be the most frequently used by the greatest number of GIS professionals. To this initial set must be added a large variety of statistical techniques (descriptive, exploratory/eda, and explanatory statistics) that have been designed specifically for spatial and spatio-temporal data. Today such techniques are of great importance in the social sciences, medicine and criminology, despite the fact that their origins may often be traced back to problems in the environmental and life sciences, in particular ecology, geology and epidemiology. It is also to be noted that spatial statistics is largely an observational science (like astronomy) rather than an experimental science (like agronomy or pharmaceutical research). This aspect of geospatial science has important implications for analysis, particularly the application of a range of statistical methods to spatial problems.
Limiting the definition of geospatial analysis to 2D mapping operations and spatial statistics remains too restrictive. There are other very important areas to be considered. These include: surface analysis —in particular analysing the properties of physical surfaces, such as gradient, aspect and visibility, and analysing surface-like data “fields”; network analysis — 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, and problems involving flows such as those found in hydrology 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 modelling 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.
A further important aspect of geospatial analysis is visualisation — 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).
[edit] Source
Geospatial Analysis - a free online website and comprehensive guide [1]
[edit] Useful links
Association of American Geographers (AAG), Spatial Analysis Special Interest Group [2]
Association for Geographic Information (AGI) [3]
Centre for Advanced Spatial Analysis (CASA): [4]
Centre for Spatially Integrated Social Science (CSISS): [5]
Centre for Computational Geography: [6]
European Commission Joint Research Centre (CEC/JRC) Geostatistics Unit: [7]
EURO Working Group on Locational Analysis: [8]
Free GIS Organisation – portal and mailing list: [9]
Geoscience Australia: [10]
International Association for Mathematical Geology (IAMG) [11]
Market Research Society, Geodemographics Knowledgebase: [12]
NCGIA Core curriculum: [13]
National Geospatial-Intelligence Agency (NGA) [14]
Open Geospatial Consortium (OGC): [15]
Royal Geographical Society/Institute of British Geographers: GIS in Teaching [16]
Spatial Analysis Laboratory, University of Thessaly, Greece: [17]
SPLINT: Spatial Literacy in Teaching [18]
University Consortium for Geographic Information Science (UCGIS): [19]
USGS: [20]
USGS Spatial Data Transfer Standard: [21]
US National Research Council of the National Academies [22]
