(ARCA) Source Data

August 28, 2011 § Leave a comment

Free and open source data has various advantages and drawbacks.Such data can be advantageously accessed online, connecting to other GIS’, and providing a considerable amount of extra data to a project’s database. This data should also come with a co-ordinate system / projection in it’s meta-data in order to be useful. Data such as the Gazetteer of Australia also are prone to errors. Outdated data such as the DCW (Digital Chart of the World), are also useful for their historic data.

These days, the various methods of data collection are facilitated by technology. This aids in improving accuracy, but also automatically provides a data-set that can be easily shared and published. Being open to the community and web, this can contribute to education and projects in similar fields, ensuring the longevity of the re-purposable data.

Topological drawings can act as sources of data. Though they are produced with scientific methodology, they must still be analyzed in their contexts as historic texts as they are prone to embellishments.

Historical Maps contribute much value as open data sources. However, like the topological drawings, they must be pre-analyzed in their context, identifying embellishments and un-executed plans. These maps must also be mapped (‘rubber sheeted’) to existing GIS projections, which often reveals slight discrepancies. Matching maps (or different sources of data), often involves transforming certain data, however, the context of the original data should always be preserved, even if only by reference.

Open source data such as open street map (OpenStreetMap.org, really should have an easily accessible key) has both benefits and disadvantages, stemming primarily from its’ crowd sourcing nature. Its open write access makes it prone to abuse, however, this also allows for easy error-correction and (mainly) accurate detailed map modification. This is especially beneficial to features that change with time (e.g. seasons), that can be reported by the local community, and analyzed by others.


  • http://www.openstreetmap.org/
  • Historical Maps in GIS – Rumsey & Williams (2002). in Knowles, Anne Kelly (ed) Past Times, Past Place pp. 1-18
  • Sydney Timemap: Integrating Historical Resources Using GIS. Wilson, Andrew (2001). History and Computing 13-1 pp.45-68

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