A new methodology for accurate digital planning of archaeological sites without the aid of surveying equipment

Abstract Technological advancements in recording systems are rapidly surpassing traditional, analogue methods of archaeological documentation. With their employment, the accuracy of recording has increased, as has the ability to disseminate digitally this information to the wider archaeological audience. The utilisation of Agisoft Photoscan for the production of highly accurate 3 dimensional models, along with a variety of secondary outputs, such as digital elevation models, are such examples. However, with reporting of archaeological excavations still firmly rooted in 2-dimensional documentation, these new technological pursuits need to produce data that is accessible to both the digital and analogue worlds. Photogrammetry has the ability to combine these two seemingly disparate techniques, with highly accurate 3 dimensional models and the production of orthophotographs, which have the ability to replace traditional analogue methods of planning. These models generally incorporate survey data from total stations or Differential GPS in order to provide a higher level of accuracy. However, numerous projects, both academic and commerical, are unable to utilise surveying equipment due to environmental or political difficulties or cost. Yet the addition of a simple right angled frame can provide both the scale and planar projection planes necessary to produce a detailed and correctly orientated (non-georeferenced) orthophotograph, which can be turned into a highly accurate digitised plan. The benefits of this method are pronounced. Not only does a photogrammetric orthophoto allow the creation of a plan that is more accurate (under 1 cm) than those recorded in the field using traditional analogue planning methods, but the time required to produce such a plan is significantly reduced. This in turn reduces the cost of recording in the field. This method provides a simplified yet highly accurate recording technique that bridges the old and new worlds of archaeological methodology.