| Geospatial Analysis - a comprehensive guide. 2nd edition © 2006-2008 de Smith, Goodchild, Longley |
| Software performance |
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Suppliers should be able to provide advice on performance issues (e.g. see the ESRI web site, "Services" area for relevant documents relating to their products) and in some cases such information is provided within product Help files (e.g. see the Performance Tips section within the Manifold GIS help file). Some analytical tasks are very processor- and memory-hungry, particularly as the number of elements involved increases. For example, vector overlay and buffering is relatively fast with a few objects and layers, but slows appreciably as the number of elements involved increases. This increase is generally at least linear with the number of layers and features, but for some problems grows in a highly non-linear (i.e. geometric) manner. Many optimisation tasks, such as optimal routing through networks or trip distribution modelling, are known to be extremely hard or impossible to solve optimally and methods to achieve a best solution with a large dataset can take a considerable time to run (see Section 7.1.4 for a fuller discussion of this topic). Similar problems exist with the processing and display of raster files, especially large images or sets of images. Geocomputational methods, some of which are beginning to appear within GIS packages and related toolsets, are almost by definition computationally intensive. This certainly applies to large-scale (Monte Carlo) simulation models, cellular automata and agent-based models and some raster-based optimisation techniques, especially where modelling extends into the time domain.
A frequent criticism of GIS software is that it is over-complicated, resource-hungry and requires specialist expertise to understand and use. Such criticisms are often valid and for many problems it may prove simpler, faster and more transparent to utilise specialised tools for the analytical work and draw on the strengths of GIS in data management and mapping to provide input/output and visualisation functionality. A related approach is to develop solutions using high-level programming facilities either: (i) within a GIS (e.g. macros, scripts, VBA, Python); (ii) within general purpose data processing toolsets (e.g. MATLab, Excel); or (iii) utilising mainstream programming languages (e.g. Java, C++). The advantage of this latter approach is control and transparency, the disadvantages are that software development is never trivial, is often subject to frustrating and unforeseen delays and errors, and generally requires ongoing maintenance.
At present there are no standardised tests for the quality, speed and accuracy of GIS procedures. It remains the buyer’s and user’s responsibility and duty to evaluate the software they wish to use for the specific task at hand, and by systematic controlled tests or by other means establish that the product and facility within that product they choose to use is truly fit for purpose — caveat emptor! Details of how to obtain these products are provided in Table 1‑1 and via the Web links: “Principal software products cited” section of the Appendix. The list maintained on Wikipedia is also a useful source of information and links, although is far from being complete or independent. A number of trade magazines and websites (such as Geoplace and Geocommunity) provide ad hoc reviews of GIS software offerings, especially new releases, although coverage of analytical functionality may be limited.
Table 1‑1 Sample software tools
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Type/key sectors (authors shown in brackets where applicable) |
Free? |
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Simple commercial agent-based simulation package |
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General purpose commercial agent-based simulation package |
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General purpose, comprehensive, very extensive toolsets, vector focused with substantial raster support. Cross industry, Open Geospatial Consortium (OGC) compliant |
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M F Hutchinson’s DEM grid generation program. Takes irregularly spaced points, contour lines and vector stream data as input and produces hydrologically consistent DEM output (implemented in ArcGIS) |
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Crime Analysis Spatial Extension (an ArcGIS extension for ArcGIS 9.1, including the former Animal Movements Extension for ArcView developed by the USGS) — see also, Hawth’s tools, below |
Y |
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Conditioned choropleth mapping. Java-based interactive mapping/visualisation tool, developed for health (cancer) studies and related analyses, environmental and education studies |
Y |
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Crime mapping and analysis program (CMAP) software toolkits and documentation (includes numerous programs, datasets, training materials, and documentation sets) |
Y |
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Java based GIS package with strong thematic mapping and exploratory data analysis facilities (this is the successor to the Descartes software) |
(Y) |
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Y |
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Linear Programming (LP)/Mixed Integer Programming (MIP) solver. Part of the ILOG Optimisation suite (see below) |
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Crime event analysis, vector (N Levine). See also crime analysis toolsets listed at http://www.iaca.net/Software.asp and http://www.ojp.usdoj.gov/nij/maps/software.html (including CASE and DRAGNET) |
Y |
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“Environment for Visualising Images”, provides powerful analysis of remote sensing image data, with support for vector format import and overlay (see also, RiverTools) |
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Analysis of ecological raster data |
Y |
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Y |
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Exploratory spatial data analysis, vector (L Anselin) |
Y |
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General purpose database-driven GIS suite |
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Geographic Resources Analysis Support System. Open source GIS with both raster and vector support. Earth sciences, government, academia. See also http://www.grassbook.org |
Y |
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Geostatistical analysis |
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Geographically weighted regression (S Fotheringham, C Brunsdon, M Charlton) |
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ArcGIS extension for spatial analysis, especially ecological applications. Shortly to be updated/replaced by the “Spatial Modelling Environment” |
Y |
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Raster-based product, especially for environmental sciences. Remote sensing, land management. See also, Land Change Modeller (LCM) for Idrisi and ArcGIS (Section 8.3.1.4) |
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Vehicle routing, scheduling and dispatching (Logistics) suite. Part of the ILOG optimisation product set (see also, CPLEX) |
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Geostatistical software for the Earth sciences |
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Surface analysis package, Java based, cross-platform (J Wood) |
Y |
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Algorithmic suite including extensive range of graph (network) analysis utilities. Provides the network analysis kernel for at least one GIS package provider |
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Locational analysis |
Y |
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General purpose, very extensive toolsets, vector focused with raster support. Cross industry, OGC compliant |
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MapCalc |
Raster-based mapping and analysis package, with very low cost variant for teaching use – no longer available |
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General purpose, vector focused with raster support. Cross industry/Marketing; HotSpot Detective (J Ratcliffe) for crime analysis |
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Multi Agent Simulation Of Neighbourhood. Open source agent-based simulation package, cross-platform |
Y |
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Matrix/mathematical package with optional mapping toolbox, image processing toolbox and statistics toolbox; free spatial statistics toolbox (L Pace) |
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MFWorks |
Raster-based analysis based on C Dana Tomlin’s map algebra and developments thereof. No longer available |
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Neural network software library for MATLab (Nabney) |
Y |
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Open source multi-agent simulation package, cross-platform (Wilensky) |
Y |
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Neural network software for MLP, SOM and various other models |
(Y) |
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.NET agent-based simulation package, aimed at urban modelling |
Y |
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Statistical analysis of circular datasets |
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Raster-based analysis with strong hydrological modelling, many aspects of which are also derived from Tomlin’s map algebra. Hydrology/Soil science |
Y |
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Open source agent-based simulation package, cross-platform |
Y |
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Hydrological analysis package; written in IDL and compatible with ENVI |
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Excel add-in for computing simple spatial autocorrelation (M Sawada) |
Y |
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Open source GIS designed with geosciences in mind, especially terrain and hydrographic analysis. Powerful raster analysis and programmability |
Y |
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Spatial analysis on a network (A Okabe et al.) — an ArcGIS toolbox |
Y |
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Network and locational analysis (S Sirigos) — V1.0 scheduled for Q2/08 |
Y |
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Spatial, temporal and spatio-temporal analysis of geographic data. Particularly designed for disease pattern analysis and surveillance |
Y |
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Facility location software (M Daskin) |
Y |
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Spatial analysis of point patterns. (R-Plus version is free) |
(Y) |
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Open source agent-based simulation package, cross-platform |
Y |
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Space-time analysis of regional systems. Some techniques mirror those in GeoDa (unrelated to the STARS logistics package) |
Y |
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Surface building and modelling package, very strong on gridding, geostatistics and visualisation. Earth sciences. Grapher, from same provider (Golden Software) also referred to in this Guide |
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Open source agent-based simulation package, cross-platform |
Y |
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Terrain Analysis System — Compact, stand-alone program. provides wide range of terrain analysis/hydrological analysis functions and index computations |
Y |
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Terrain Analysis Using Digital Elevation Models — ArcGIS Add-in/toolbar. Provides wide range of terrain analysis/hydrological analysis functions and index computations |
Y |
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Commercial space-time and statistical analysis packages (STIS — V1.5, Clusterseer V2 for cluster analysis, Boundaryseer for Boundary detection and analysis). Health |
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Commercial generic cross-platform GIS developed from image processing background. Large analytics toolset. Free “Lite” version for non-commercial use |
(Y) |
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TransCAD is the transportation-focused implementation of the Maptitude package, with very strong network analysis and related facilities. Transport, Marketing |
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Excel spreadsheet for computing ellipsoidal distances (download link) |
Y |
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WinBUGS with GeoBUGS is a Bayesian statistical analysis package that uses Markov Chain Monte Carlo ) (MCMC) methods. Health |
Y |
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General purpose modelling and optimisation suite (free student edition) |
(Y) |
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Zone design system. University of Leeds, UK |
Y |
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