CAA UK 2001 - Abstract

Applications of photogrammetry and image analysis in rapid archaeological data collection: assessing rates of decay in excavated stone circles.
Paul Carey
School of Geography, Queen's University, Belfast

The Copney Stone Circle Complex (CSC) is a Bronze Age site forming part of the Mid-Ulster Stone Circle Complex.It was partially excavated in 1994 when part of the bog hosting the site was excavated.� The complexity of the CSC makes it unique amongst the Mid-Ulster stone circles.Consequently, the accurate recording of the details of the site and its components is essential.Immediately the site was excavated, it was noted that the site was decaying at an alarming rate.The rapid preservation of the site�s original detail and consequent decay was therefore of importance.

A photogrammetric approach was taken to recording the site, facilitating the rapid generation of digital terrain models for the surrounding area and for the stone circles themselves.Accurate digital models of the spatial characteristics of the site were obtained for future record.The advantages of this technique are that the acquisition of imagery and processing of the entire site is rapid and non-destructive, the surveying technique is accurate, ground surveying is minimal and a single operator can carry out all of the processing necessary to characterize the site.

Output from the system provides both 3D and 2D models that can be used in site recording, orthophoto generation, modeling modifications to the landscape around the site, 3D flythrough and virtual model generation.

Repeat images taken at timed intervals on the site can be processed in the same way as the originals, facilitating comparison of the 2D and 3D models generated.The sequential measurements made on the site images can be used to assess not only the positioning and state of the site, but also to assess the rate of decay of the stones and the spatial distribution of rates of decay. In this way, remedial operations can be directed to positions on the site where they are going to be most effective.

Finally, the incorporation of the data generated for the site into spatial databases and web-based presentations for the public, and for academic research, is relatively straightforward.

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