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Laser scan of Vase Urn

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Laser scan of Vase Urn Interior

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Laser scanning in process

Archaeology & History:

The Ancient & the Modern

James Eogan, project archaeologist with Tramore House Regional Design Office, reports on the novel use of three-dimensional laser scanning technology to record a Bronze Age pottery vessel.

Excavations by Joanna Wren and a team of archaeologists from Headland Archaeology Ltd in advance of construction of the N25 Waterford City Bypass in Newrath, Co. Kilkenny, uncovered a previously unknown ring-ditch (c. 4 m in diameter) in June 2004. Ring-ditches are one of the simplest prehistoric burial monuments in Ireland, comprising a small ditch dug to enclose a circular area that can range from 3 m to 20 m in diameter. Sometimes the earth dug from the ditch was used to form a mound in the central area, or a bank on the outer edge of the ditch. Excavation has shown that ring-ditches were constructed from the Early Bronze Age to the Iron Age; burials have been found in the area enclosed by the ditch, the mound (if one were present) and in the ditch itself.

Centrally located within the ring-ditch was a large, flat slab of rock that originally would have been covered by a mound of the soil dug from the surrounding ditch. When this slab was lifted, a small, stone-lined pit was revealed and it contained an inverted burial urn of a type known by archaeologists as a Vase Urn. The urn was excavated carefully and was found to contain the cremated bones of an adult male, who was probably in his mid- to late thirties when he died, of unknown causes, almost 4,000 years ago.

The urn is just under 290 mm high and has a maximum diameter of just under 300 mm. It was adorned with three ‘zones’ of decoration, which were incised onto the surface of the pot using a pointed tool while the clay was still wet: the neck is decorated with six horizontal lines; the belly is decorated with a series of opposed triangles (80 mm high) filled with alternating oblique lines, below which are three horizontal lines; the lower body is decorated with an irregular criss-cross pattern.

Three-dimensional laser scanning is normally used for the modelling of components in the airmotive industry and for other precision engineering applications. The scanner can be used to scan an object of any size in any accessible location, from small archaeological objects in a conservation laboratory to large, sculpted architectural features outdoors. The low-powered laser safely recorded the surface of the object—without the need for any physical contact between the object and the scanner. The scanning results in a model that can be accurate to +/- 0.05 mm of the original. The technology records fine detail and relief marks that could easily be missed by the naked eye or ordinary photographs. Using the free, viewing software, scanned objects can be ‘handled’ in 3-D, i.e. viewed from any angle and measured with precision.

The full potential of this relatively new technology is still being explored, but the following benefits have been noted. Laser scanning facilitates the detailed examination of fragile artefacts without the necessity for repetitive handling. Dimensions can be measured and the decoration on the pot can be examined in detail. As laser scanning generates a digital model, it makes it possible for specialists in different locations to examine artefacts in detail, without the physical transportation of either artefact or specialist. This technology enables the depiction of objects ‘in the round’; in the particular instance of recording the Vase Urn from Newrath, this provided a significant benefit over traditional methods of representing decorated pottery vessels, where typically only one-quarter of the decorated surface is shown. Images of the digital model can be animated to allow the model to be displayed on websites and in video presentations. The digital model can also be used to make accurate replicas of the vessel for public display, which minimises the amount of transportation and handling required of the original object.