The Essential Guide to GIS

When most people think of GIS, they are actually thinking of GIS software running on a computer. The choice of GIS software and the hardware to run it on is very important, and mistakes can be costly. Choosing these tools used to be simple. There were few vendors of GIS software, and the hardware required to run it was powerful, often specialised and very expensive. The software offered many levels of functionality, was very complex and generally user hostile!

Recently, the market has changed dramatically. There is now an enormous range of software which is labelled ëGISí and which is available for almost every computer platform. In particular, there has been a divergence into two camps; the high-end GIS and the desktop mapping/GIS package.

The high-end GIS is a development of early GIS software; very powerful, fully functional GIS toolkits which usually require powerful UNIX-based workstations. They provide all the functions you would require for most applications. Data input tools, for example, provide the ability to capture data from existing paper maps and records, from existing digital data and primary data collection methods such as surveying and GPS.

These systems also carry out the management of very large databases, with many users making individual changes. This is an extremely complex process, even with the appropriate tools. The efficient storage of complex spatial data sets is another problem which requires specialised software tools; a comprehensive suite of data archiving tools in particular. Analysis of the geographical information on a high-end GIS ranges from a simple query of the data set, to the creation of buffers and the combination of data sets to create an environmental model.

The presentation of the contents of a spatial database or the results of complex spatial analysis have often been overlooked by the designers of GIS software. Tools for producing cartographic output or sophisticated reports are essential for many applications.

The high-end GIS is really only a set of programs and will often require customisation for a particular application. Customisation may include the development of Graphic User Interfaces (GUI) and also the development of specialised tools relating to a particular application. As might be expected, such complex software requires considerable support from trained staff.

A major development in the GIS software market over the past few years is the so-called Desktop Mapping/GIS package. These have developed with the realisation by vendors that not all users of spatial information are GIS experts; many people just want to carry out simple queries of spatial data sets.

As the name suggests, desktop packages are designed to run on desktop personal computers usually using a windows and mouse-based interface. These packages have fewer functions, and are primarily designed for simple analysis and the production of maps and graphs. A major limitation of desktop packages has been a difficulty in importing data. This is now being addressed by many traditional data suppliers and new value-added publishers. For a few hundred dollars, these packages are an excellent introduction to GIS.

The term "enterprise computing" has recently become popular, and is used to describe the situation where all the users of an organisation or enterprise have access to a central information resource. In GIS terms, this might mean the vast majority of users using desktop GIS to query a central data set over a network. The central data base would be maintained and updated by specialists using high- end GIS toolkits.

When considering GIS software, you need a checklist of points:

What are the hardware requirements? Do these conform to the policy within your organisation? Do you already have relevant skilled staff?
What data model(s) does the system use? Does it have the analytical tools required for your application?
Will you be able to use or convert your existing data? Does the GIS support the existing Database Management Systems in use?
How easy is it to input data? Can the system import digital data from your national mapping agency e.g. NTF in the UK or SDTS in the US?
How easy is the system to customise? It is possible to design your own interface, and add features when requirements change? Can you do this yourself ?
What level of technical support is provided? Is there a dedicated technical support team? Does it guarantee response times? Remember: it is often difficult to deal with a technical support department in a different country.
Who are the existing users of the system? Can you talk to any similar organisations to your own who already use the software? Are there user groups?
How easily can the system be integrated to your existing Information Systems? Can it be networked? Does it produce standard format files that can be opened by your word processing, spreadsheet packages etc.?
What documentation is supplied? Is training available? How user friendly is the system? Is there context sensitive help available? Are there training courses? How expensive are they ?
Are there maintenance charges? (Unlike office automation software such as word processors, GIS - particularly high-end GIS - may be subject to a yearly maintenance charge, which covers support and upgrades which occur very frequently!!).

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