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County Clare 1842 Ordnance Survey Historical Map Digitisation Project
 

In July 2004 Clare County Library decided to build an Internet Geographical Information System for the users of Clare County Library's website, based on the 1842 Ordnance Survey 6-Inch maps of County Clare, and integrate the maps with other online resources available on the website. More than 2,000 townland pages, and in excess of 6,000 monument pages were created in conjunction with this project. Over 6,000 images were also created as 'tiles' from the original scans of the Ordnance Survey maps.

The 1842 Ordnance Survey 6-Inch maps are a valuable tool for historical research. Clare County Library owns two complete set of the original maps. They are visually beautiful and contain detailed information down to the level of individual houses and field boundaries, and show all important historical and topographical feature. The maps are fragile and irreplaceable and cannot be copied without damaging them. As the physical maps are only available for viewing at Clare County Library’s Local Studies Centre in Ennis, public access to them is limited. Clare County Library wanted to give unrestricted access to these maps through the World Wide Web.

Rainer Kosbi, a software developer and historical researcher, was at this time exploring a new approach for an Internet Geographical Information System (GIS). His project platform "Tracemaps SG" makes use of the new non-proprietary Internet standard SVG (Scalable Vector Graphics). SVG is set to become a native part of modern web browsers. It is, however, already today integrated in many web pages thanks to Adobe’s SVGviewer, a freely available plug-in which works particularly well with the most common browser, Microsoft’s Internet Explorer (5.5+). These technical corner stones allowed the realisation of a Clare County Library system that can grow in the future, be cross-referenced with existing web pages, easily installed in local networks (with a simple copy command), published on a CD or DVD and even be used in a powerful off-/on-line combination.

As a first step in this project, the bound volumes of maps were sent to Reilly’s Bookbinders of Wicklow, who unbound them, in readiness for scanning. For the scanning portion of the project we contracted General Business Machines (GBM) of Lower Hartstonge Street in Limerick. Having been involved in reprographics for almost 40 years we felt they would have the neccessary skills and systems to complete the task to the standards required.

The scanning comprised of 76 maps, with each split into two sections. Following a good deal of testing and sampling of results,
these sections were finally scanned in 256 colours at 400dpi and saved as LZW TIFF files. GBM had recommended this file format as it reduces the physical file size with no loss of definition. Each of the 152 sections were aligned & merged to recreate the 76 original maps. These maps were then burned to CD for archival purposes and a copy sent to Rainer Kosbi for further processing.

The average LZW compressed file size at this stage was 75 MB, which usually turned into approximately 135 MB when loaded into a computer’s memory – totally unsuitable for a distribution over the Internet. The eventually released version offers only half the possible resolution, with a loss in quality caused by necessary JPEG compression. However, even this compression would have still left us with files of several megabytes, not to mention that some cross-sheet regions would have required the opening of two or even four files at the same time. Rainer Kosbi's design solves the problem with a split-up of the sheets into 'tiles', and their re-joining when needed for display. In the process 6,638 tiles were created with an average size of 67 kilobytes. Two to six tiles are normally enough to fill a screen at standard zoom.

However, a Geographical Information System should not only allow a continuous, moveable and zoom-enabled display. Searchability and interactivity are also essential parts. 2,235 names and positions of townlands and towns were therefore picked up from maps; 6,398 monument characteristics gained from a Dúchas downloadable database, and as many links created to and from web pages. Additionally, a vector copy of the county outlines was produced. So far it only serves as a background. Such wire-graphics are the real domain of SVG, however. A whole range of interactive feature layers, for examples of parish and townland regions, can be developed to extend the abilities of the current search window

Clare County Library placed this GIS in September 2005 on its website, with the intention of utilizing these maps to further integrate local studies and genealogical information on the website. For example, by clicking on a townland marked on a map, all information on that townland (Census records, Griffith’s Valuation, Photographs, Trade Directories etc. etc.) will eventually be presented. The maps will also provide and demonstrate new relationships between existing data on the site, and users will be able to use feature layers produced from the maps as a new search facility.

Anthony Edwards,
Maureen Comber,
Project Managers,
26th October 2005

Postscript:
In early 2010 Rainer Kosbi developed MapBrowser, a Flash-based maps system as an alternative to his SVG maps system. MapBrowser will run in the majority of browsers using Adobe's Flash Player on Windows and Apple Mac personal computers and can be used to easily access our online maps.

In January 2012 we launched the Clare GMaps, which are based on the Google Map system, allowing Google Maps and satellite views to be overlaid with historical maps of Clare from 1842. This new system, also developed by Rainer Kosbi, uses many of the same controls as Google Maps, and we have linked it to the thousands of pages on this website dealing with the archaeology, history and administrative divisions of County Clare.

In July 2013 we launched the Clare Genmaps, which utilise the ESRI ArcGIS API for FLEX, allowing ESRI, Bing and Open Street Maps to be overlaid with historical maps of Clare from 1842. This new system, developed for us by Rainer Kosbi, allows us to represent surname distribution from the 1820s Tithes, 1855 Griffiiths and 1901 Census datasets as interactive heatmaps linked to the extensive data on our website.The system uses many of the same controls as our GMaps system.


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