Ogham stones are among Ireland’s most remarkable national treasures. These perpendicular-cut stones bear inscriptions in the unique Irish Ogham alphabet, using a system of notches and horizontal or diagonal lines/scores to represent the sounds of an early form of the Irish language.
The stones are inscribed with the names of prominent people and sometimes tribal affiliation or geographical areas. These inscriptions constitute the earliest recorded form of Irish and, as the earliest written records dating back at least as far as the 5th century AD, are a significant resource for historians, as well as linguists and archaeologists.
Arraglen stone, Mt Brandon
Scanning the stones
The stones vary in size, with an average height of approximately 1.5m. They are often located in remote and exposed parts of Ireland which adds to the challenge of recording to high resolution. A forensics tent is used to create a controlled lighting environment and ensure measurement can proceed regardless of the highly unpredictable Irish weather. To ensure sufficient power for the scanner and laptop a portable generator is often used as sites can be a long way from mains power.
Scanning Arraglen stone
Scan settings / Resolution
Scanning is undertaken with the fastest speed setting and with a minimum 400 mm depth of field. The data is recorded with sufficient overlap between scans to ensure easy registration.
Models & Outputs
Post-processing is done in Artec Studio 9 software: individual scans are edited, aligned, before a final surface is generated using global registration, fusion, and a small objects filter algorithm. If required, a textured surface can also be created. To complete the project a model is exported from Artec Studio 9 as an .obj file. For dissemination purposes a 3D pdf of the model is generated (using Geomagic Studio 2012) and is available to download from the project website.
Texture & surface models – left Dunmore, right Kilmalkedar, both Dingle Peninsula, Co Kerry
3D scanning was deemed the best method for this recording due to the fact that the Ogham inscriptions are quite subtle and are prone to weathering. 3D data would also allow for the removal of colour data which could perhaps reveal inscriptions which were previously unknown or hard to decipher. The geometry of the stone is important and the data would allow desktop users to take measurements of the stones etc.
Mobilizing equipment to Mt Brandon
The Discovery Programme and the Dublin Institute for Advanced Studies
The Discovery Programme – www.discoveryprogramme.ie
Ogham in 3D – http://ogham.celt.dias.ie