Software, GIS

Software Suppliers

GIS software is available from a substantial number of sources, both commercial and noncommercial. The major suppliers of the former include Autodesk, Bentley, ESRI, Intergraph, Leica, and MapInfo. Among the latter, the most notable include the GRASS and IDRISI product sets. There is no publicly available independent source of information providing details of each product, their features and principal application areas, and their market shares. However, it is clear that at present, ESRI, with its flagship ArcGIS suite of products, is the principal specialist commercial supplier of GIS software. In addition, many major information technology (IT) businesses, including Microsoft, Oracle, Google, SAP, and IBM, have substantial operations devoted to GIS software and the related areas of spatial Web-based services and GIS database management systems.

[Page 391]A number of GIS packages and related tool sets have particularly strong facilities for processing and analyzing binary, grayscale, and color images. They may have been originally designed for the processing of remotely sensed data, from satellite and aerial surveys, but have developed into much more sophisticated and complete GIS tools (e.g., MicroImage's TNT product set; Leica's ERDAS Imagine suite of products; and RSI's ENVI software and associated packages, such as RiverTools from RIVIX). Alternatively, image handling may have been deliberately included within the original design parameters for a generic GIS package (e.g., Manifold) or may simply be tool sets for image processing that may be combined with mapping tools (e.g., the MATLab Image Processing and Mapping Toolboxes).

Commercial products rarely provide access to source code or full details of the algorithms employed. Typically, they provide references to books and articles on which the procedure is based, coupled with online help and “white papers” describing their parameters and applications. This means that results produced using one GIS package on a given data set can rarely be exactly matched to those produced using any other package or through handcrafted coding. There are many reasons for these inconsistencies, including differences in the software architectures of the various packages and the algorithms used to implement individual methods; errors in the source materials or their interpretation; coding errors; inconsistencies arising out of the ways in which different GIS packages model, store, and manipulate information; and differing treatments of special cases (e.g., missing values, boundaries, adjacency, obstacles, distance computations, etc.).

Open source and not-for-profit packages sometimes provide source code and test data for some or all of the functions provided, although it is important to understand that “noncommercial” often does not mean that users can download the full source code. Access to source code greatly aids understanding, reproducibility, and further development by those with the necessary programming skills and knowledge. Such software will often also provide details of known bugs and restrictions associated with functions—although this information may also be provided with commercial products, it is generally less transparent. In this respect, noncommercial software may meet the requirements of scientific rigor more fully than many commercial offerings, but it is often provided with limited documentation, training tools, cross-platform testing, and/or technical support and thus is generally more demanding on the users and system administrators. In many instances, open source and similar not-for-profit GIS software may also be less generic, focusing on a particular form of spatial representation (e.g., a grid or raster spatial model). Like some commercial software, it may also be designed with particular application areas in mind, such as addressing problems in hydrology or epidemiology.

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