Requisites for the use of geographical information systems (GIS) software for redistricting can be divided into the following three categories: computer systems and software, spatial and other data, and users. In addition, a general understanding of GIS and the potential advantages and disadvantages of its use, as well as a frame of reference that permits its use, are important considerations in adopting GIS for redistricting.
Computer systems and software
GIS software runs on the whole spectrum of computer systems ranging from portable personal computers (PCs) to multi-user supercomputers. Regardless of what hardware system is chosen, a number of elements must be considered for the GIS software to operate effectively:
- the computer must have a processor with sufficient capacity (speed and RAM) to run the GIS software and sufficient disk capacity to store large volumes of data;
- a high resolution colour graphics screen to view the output;
- data input devices such as digitisers and scanners if paper data must be transformed into electronic data;
- data output devices such as printers and plotters.
Hardware requirements are both dependent on and determining of software requirements; hardware limitations may mean that particular software products cannot be utilised, while the availability of software can dictate what sorts of hardware must be purchased.
Software refers to both the operating system and specific application packages. GIS applications run in a variety of operating systems such as UNIX, Windows NT and Windows XP using GIS software programs such as Arc/Info, Intergraph, MapInfo or Maptitude or customised GIS software packages for redistricting.
Cost can be a key factor in the choice of hardware and software. Budgetary constraints, especially in many developing countries, limit the choice of which computer system and software can be used.
Data
Data includes both the cartographic database needed for using GIS applications as well as any accompanying attribute data (primarily population data in the case of redistricting). Data availability and accuracy—and especially the availability of digital cartographic data—are some of the most important requisites for the development of GIS capabilities. The extent to which GIS is used it is often dictated by the availability of digital cartographic data, or more often, the willingness to dedicate resources to creating such a database.
Many countries have produced a complete set of uniform, digitised maps covering the entire country, but others have only begun—or have not yet begun—this process.
Developing countries are faced with a number of limitations in the use of GIS applications that revolve around issues such as cost, training of specialized personnel, and data availability. As needs for resolving questions related to urban and rural land use, transportation, housing, and environmental pollution are emerging, there is a pressure to adopt GIS technology and to develop computerised maps which can then be adapted for use in redistricting.
Users
Users refer to trained personnel able to operate the GIS system. The main requisite for GIS users is the ability to work with computers to manipulate basic GIS software and databases as well as some general geographic and cartographic knowledge in order to be able to use GIS for redistricting.
Many GIS packages are difficult to use without proper training. The language barrier may pose an additional problem as many GIS manuals and programs—especially those designed specifically for redistricting—are written only in English.
