Typically in the past, the focus of geospatial data access was supplier side with a strong emphasis on technology and community based standards and specifications. With the growth of the Internet, in particular Web based technologies, access has become a demand driven operation. Consumers expect simple discover and access to cheap (or free) data in simple standard formats that can be used in desktop applications. Increasingly non-traditional suppliers are offering geospatial services, an example being Terraserver (http://www.terraserver.com/). The ability to leverage off other major developments such as the World Wide Web, and in some cases electronic commerce, has allowed broader participation in the Industry. The further democratisation of access to geospatial data thus enables value-added suppliers to create new data products and services.
The range of issues from an organisational point of view can be categorised two ways: 1) how broad is the client group; 2) how broad is the supplier group. In both cases issues tend to appear and grow as the groups become broader. In general issues revolve around copyright, licences (end user vs. reseller), cost, privacy, data formats and standards.
For example, if the client group is only internal staff then issues such as cost and copyright might not play a factor. As the scope of the client group grows to a limited number of known clients then there are straightforward mechanisms to control access. However, providing broad access to large group of potentially anonymous clients.
Similarly, as the size of the supplier group grows then issues appear. It is easier to establish a common policy for one or two organisations than it is for many. Typically each organisation has a business model (or non-business model!) that reflects its mandate and environment. The types of data and services it provides, the form and representation of the data, the quality and standards for the data all reflect this business model. Trying to bridge these issues between disparate organisations is an exponential problem.
The overlap between information managed by subject-specific communities in possibly parallel infrastructures can compound problems of data discovery and access. This can be viewed from either the consumer or supplier perspective. For example, as communities such biodiversity or geoscience specialists attempt to leverage a combined spatial data infrastructure to support their own goals they introduce new factors. These could be new standards or convention that they commonly require, it could be a new attribution requirement on the data not previously realised, or it could be the need to provide common access to data not otherwise visible from a spatial data infrastructure.
Several trends can be noted in the treatment and handling of geospatial data. Typically in the past the first concern of a data custodian has been what format the data is stored or managed in. Increasingly the trend is to move one level up and only worry about the interfaces to the data. This allows the data to be managed in the best manner possible, while providing open, standards based access. A consequence of this, however, is that the content of the data must be of a sufficient quality to support these interfaces. Often existing data is not accurate enough, up to date or lacking in attribution.
Another trend is in the organisation of the data itself. There is an evolution that starts back with traditional paper products. These migrated into discrete digital files that were typically stored offline, e.g., on a tape rack. As mass storage became more affordable these files found themselves living on online media (magnetic or optical) for easier access. This last step is an important one when you couple it with the developing of ubiquitous, wide area internetworking, i.e. the Internet. At this point a supplier was empowered to deliver data online.
More recently the trend has been to merge all the discrete data sets together into a single, seamless data warehouses, which have spawned the development of direct data access services. This has been enabled by developments in mass storage and spatial database technology. This step is also proving to be hard on the data, revealing inconsistencies in data accuracy and quality. Recent infrastructure developments allow the creation of virtual data warehouses which federate multiple instances of a data warehouses into a single logical entity.