The proof is in the details: the analysis of the excavation artefacts

Our excavation of the pre-colonial shipbuilding yard at Horeke has so far uncovered thousands of artefacts from both the domestic, and industrial aspects of the site. These artefacts will be taken to Otago University for full archaeological analysis using a variety of methods. However,  we have already started the process on site, for example we are using a photographic technique called Polynomial Textural Mapping (PTM)  to create images of some of the interesting artefacts we are finding. These images let us get a better look at the surface of small artefacts like flints, coins and seals as well as large, but often worn, engravings on surfaces such as gravestones.

ptm interface.png
The PTM interface showing one of the gun-flints from the site

PTM uses software to analyse and combine photographic information in such a way as to enhance the surface texture of a subject. The finished PTM is an interactive image that allows you to change the angle of light, magnify sections and add renderings to enhance various aspects of the image. Snapshots of any view can be captured and then used for analysis, illustrations, documentation etc. To produce a PTM you need to take many photographs of a subject under different lighting conditions.

at work
The PTM lighting rig in action.

One of the significant artefacts that we have found was an early New Zealand postal seal. Significantly, the Horeke Post Office was opened in 1840, the first in New Zealand, and these seals were used to lock the mail bags. The photos below show a normal image of the seal and an enhanced image from a PTM.

This artefact has proven to be particularly important, as the presence of the seal within Layer 2 of Area 4 has confirmed that this layer is no earlier than 1840, and as such, post-dates the shipbuilding activity in this area. Based on this information we have continued to excavate in this area and have been rewarded with considerable evidence of shipbuilding, but more about this at a later date!

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One thought on “The proof is in the details: the analysis of the excavation artefacts

  1. Really thankful for you guys sharing the progress, and explanations pertaining thereto.
    This above PTM insight is to me exciting, and great to read and see. I especially appreciate the daily updates (including social aspects and local comment etc), as being so far away makes it impossible for me to come visit and see first-hand the skillsets so ably applied by such a professional team, some from the areas I lived in in NZ 🙂 .

    Liked by 1 person

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