This chapter provides an overview of the rise of 3D technologies in the practice of maritime archaeology and sets the scene for the following chapters in this volume. Evidence is presented for a paradigm shift in the discipline from 2D to 3D recording and interpretation techniques which becomes particularly evident in publications from 2009. This is due to the emergence or improvement of a suite of sonar, laser, optical and other sensor-based technologies capable of capturing terrestrial, intertidal, seabed and sub-seabed sediments in 3D and in high resolution. The general increase in available computing power and convergence between technologies such as Geographic Information Systems and 3D modelling software have catalysed this process. As a result, a wide variety of new analytical approaches have begun to develop within maritime archaeology. These approaches, rather than the sensor technologies themselves, are of most interest to the maritime archaeologist and provide the core content for this volume. We conclude our discussion with a brief consideration of key issues such as survey standards, digital archiving and future directions.

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This chapter presents proof of concept results from a program of in situ experimental and shipwreck survey measurements using non-linear (parametric) sub-bottom profiler (SBP) acoustic technology. Currently adopted acoustic methods have practical limitations for in situ management purposes for underwater sites with buried archaeological material. Sidescan and multibeam sensors do not quantify material buried below the seabed; linear SBP surveys are challenging to operate in very shallow water and have difficulties with respect to interpretation in the top 30 cm of the seabed; and confidence estimates for parametric SBP depth of burial measurements have yet to be published. The prime purposes of this research, consequently, are: to quantify shallow buried archaeological sites in 3D with confidence estimates, by measuring the depth of sediment cover, thickness and lateral extent of buried archaeological material; and to investigate relationships between acoustic waveform parameters and the type and degradation condition of that buried material. This improved measurement and interpretation capability, when combined with the other geophysical search tools such as multibeam echo sounders and magnetometers, will also aid in the assessment of the archaeological research potential of underwater sites.

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The application potential of parametric sub-bottom profilers (SBPs) to in situ management of underwater archaeological sites at risk from degradational loss of shallow-buried materials is presented. This approach is based on the process-driven in situ preservation and research frameworks advocated by the 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage and provides a basis for greater uptake by the archaeological community. Results from research at a purposely prepared sub-seabed site and on the adjoining James Matthews (1841) wreck site in Western Australia demonstrate how noninvasive SBP-derived data support responsible management of underwater cultural heritage (UCH) sites by: (1) identifying and/or confirming the presence of sub-seabed UCH material, (2) identifying the potential level of risk of further material loss from ongoing degradation, (3) providing key information with which to make a sound in situ management or site-research plan for the sub-seabed material, and (4) delivering monitoring feedback regarding the success of in situ management actions.

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