What is a Spatial Data Infrastructure?
A Spatial Data Infrastructure supports ready access to geographic information. This is achieved through the co-ordinated actions of nations and organizations that promote awareness and implementation of complimentary policies, common standards and effective mechanisms for the development and availability of interoperable digital geographic data and technologies to support decision making at all scales for multiple purposes. These actions encompass the policies, organizational remits, data, technologies, standards, delivery mechanisms, and financial and human resources necessary to ensure that those working at the national and regional scale are not impeded in meeting their objectives (Masser, 2005 and GSDI, 2004).
Objectives of a SDI
The overall objective of an SDI is to maximize the reuse of geospatial data and information.
- SDIs cannot be realized without coordination (especially by governments).
- SDIs must be user driven, supporting decision-making for many different purposes.
- SDIs implementation involves a wide range of activities, including not only technical topics such as data, standards, interoperability, and delivery mechanisms, but also institutional arrangements, policies, financial and human resources.
The term infrastructure is used to promote the idea of a reliable and supporting environment, analogous to a road or a telecommunication network, facilitating the access to geoinformation by using a minimum set of common practices, protocols, and specifications (GSDI, 2004). This allows the movement of spatial information instead of goods.
Encompass the sources, systems, network linkages, standards and institutional issues involved in delivering spatially-related information from many different sources to the widest possible group of potential users.
What are the principal components of a SDI?
In order to be used, people need to know that the data exist, and where to obtain it.
- They need to be authorized to access and use the data.
- They need to know the history of the data capture, in order to interpret it correctly, trust it and be able to integrate it meaningfully with data coming from other sources.
- They need to know if the data depends on other data sets, in order to make sense of data.
Consequently, to leverage the full potential of geospatial data, an SDI must be made of different components to allow users to find, discover, evaluate, access and use these data, namely:
- A clearly defined core of spatial data.
- The adherence to known and accepted standards and procedures.
- Databases to store data and accessible documentation about the data, the so-called metadata.
- Policies and practices that promote the exchange and reuse of information.
- Adequate human and technical resources to collect, maintain, manipulate and distribute geospatial data.
- Good communication channels between people/organizations concerned with geodata, allowing the establishments of partnerships and shared knowledge
- The technology for acquiring and disseminating data through networks.
- Institutional arrangements to collaborate, co-operate and coordinate actions.
The main material components of a SDI are:
- Catalog of metadata
- Web Map Server with WMS/WCS/WFS and other functionalities
- WMS Client: viewer to access the geodata, to consult and download it, etc.
- Network of accessible Web Map Servers, described by services metadata and containing geoinformation described by data metadata
- Data harmonization
- Geographical Information System functionalities
- Downloading of data
- Masser I. (2005) The Future of Spatial Data Infrastructures, ISPRS Workshop on Service and Application of Spatial Data Infrastructure, Oct.14-16, Hangzhou, China, 9p. http://www.commission4.isprs.org/workshop_hangzhou/papers/716%20Ian%20Masser-A001.pdf
- GSDI, 2004. Spatial Data Infrastructure Cookbook v. 2.0. Global Spatial Data Infrastructure Association, viewed on 16 December 2004, http://www.gsdi.org/gsdicookbookindex.asp