Multi-image photogrammetry as a practical tool for cultural heritage survey and community engagement

Multi-image photogrammetry is rapidly emerging as an important archaeological tool due in large part to the increasing level of automation in off the shelf software. The technique can offer significant reductions in the cost of archaeological survey and in the enhancement of survey results and is of particular value therefore to archaeologists working in contract-led context, which in many areas accounts for the majority of archaeological work (up to 80% in Scotland for example). Recent advances in multi-image photogrammetric software have resulted in highly automated workflows and significantly reduced the burden of technical knowledge required to produce survey results of an acceptable standard. Although the majority of multi-image photogrammetry surveys are still undertaken in an academic context the technique is increasingly being used by a far wider proportion of heritage professionals, many of whom are not first and foremost specialists in photogrammetry. The adoption of such highly automated workflows presents certain risks with regard to accuracy and reliability of results as noted by Remondino et al. (2012, 52). However the enormous potential of the technique for rapid and accurate survey and for reduced costs cannot be ignored and the challenge we face is to ensure that the highly automated workflows adopted by archaeologists in contract-led contexts are robust and reliable and underpinned by guidance and knowledge exchange. This paper is not intended as a comprehensive technical review of the technical aspects of the technique or of its development but instead focusses on highlighting its potential as a practical everyday tool for archaeological practitioners to apply in two of the main types of contract-led archaeological work, rapid survey and community engagement. A non-technical overview of the technique is given followed by case studies illustrating how the technique has been applied successfully in a non-academic contract-led and community engagement context. These surveys have been undertaken with very limited budgets for both survey and post-processing of data and typically with very limited time frames. In each case study, use of multi-image photogrammetry has allowed for better, faster and more cost-effective results than would otherwise have been possible. Case studies include a survey of an Iron Age fort, a rapid survey of exposed segments of an intertidal wreck, both commissioned for heritage management purposes and a community survey of a 17th century gravestone undertaken by children under the age of 16. Finally the obstacles to wider adoption in the contract-led sector are discussed and it is argued that a concerted approach is required to create and disseminate simple and