Tri-Closure: A Quick And Easy Way To Create A Local Coordinate System For Underwater Photogrammetric Recording

Summary

To use 3-D photogrammetric models as scientific data, it is essential for archaeologists to use local coordinate systems to constrain their photogrammetric models to 1:1 scale. This enables archaeologists to take measurements directly from their models. Direct Survey Methods (DSM) are often used to create local coordinate systems; however, DSM often requires several days of diving operations, which may become problematic when recording large or deep-water sites.

As a quick alternative method, the authors propose "Tri-Closure." This method uses only three control points, placed to form an isosceles triangle. The coordinates of the control points can be calculated using the Pythagorean theorem. After the initial photogrammetric recording, coordinates of any points within the enclosed area are automatically established. Tri-Closure is advantageous for photogrammetric recording because it requires only one or two diving operations to set up. In this paper, the authors will explain the step-by-step process of the proposed method.

This Resource is Part of the Following Collections

• The Application of Traditional and Innovative Documentation Techniques in Nautical Archaeology   •
• Society for Historical Archaeology 2017

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Individual & Institutional Roles

Contact(s): Society for Historical Archaeology

Record Identifiers

PaperId(s): 658