An exciting partnership between DEW’s Maritime Heritage Program, within Heritage South Australia, and local drone photography company Dronology has the potential to revolutionise the archaeological management of shipwrecks in South Australia.
The ship at the centre of the trial partnership is the popular
at Mutton Cove, near Outer Harbor. Excelsior shipwreck
Using a mapping technique known as photogrammetry, overlapping drone-captured images of the wreck have been entered into Agisoft Metashape software to create a digital 3D model, enabling the unit to easily measure the site to pinpoint accuracy, according to Senior Maritime Heritage Officer Rick Bullers.
‘The beauty of having a 3D digital model is that even if you’ve only got one or two accurate measurements of the site and you enter that into the model, you can then use the model to measure any part of that site,’ he said.
‘So, if you want to know how long the rudder shaft is, once you’ve got a couple of easily accessible measurements, you can plug that into the model and measure that shaft in the model and know exactly how long it is.’
Rick said the real value of the 3D model lies in how it can be used to track the deterioration of shipwrecks over time using minimal resources.
‘The drone only has to fly over the site for an hour or so to collect the photos and then the software creates the 3D model, so it’s a minimal investment of time. Given this, it’s very easy to go back in five years’ time, do the same thing again and compare the measurements to determine what deterioration has occurred,’ he said.
Previously the only way to measure a site was by getting a team together in the right weather conditions for several days at a time and going in with a tape measure and measuring.
While the availability of these tools doesn’t remove the need for site-based archaeology, its ease of use means it has the potential to be used in a number of areas.
‘If we make the models available online, it makes shipwrecks accessible to people who are disabled or have difficulty accessing an underwater site, plus it’s an easy tool to use for measuring the rate of a site’s decomposition, or assessing whether a site is stable,’ Rick said.
‘If this type of photogrammetry took place over a number of shipwrecks on a regular basis, say every five years, we could develop accurate information about the way different types of vessels break down in similar environments, for instance the corrosion rates of iron vessels compared with steel ones, which would help us determine where best to put resources into managing a wreck site.
‘The technique can be used for underwater sites as well, although collection of useable photographs is more difficult. We are currently in the process of developing a 3D model of the historically significant barque
South Australian at Encounter Bay, which will be used for baseline assessment of the site’s stability, as well as informing future targeted archaeological excavation.’
And while the work being done on
Excelsior in partnership with Dronology is only a case model at this stage, that’s not all that Rick plans to use it for.
‘There’s the potential to use this technology on historical heritage sites as well, such as old huts, and record them over time and then use that material from an interpretative aspect,’ he said.
‘We’re also talking with Dronology about augmented reality for the Torrens Island Quarantine Station. A visitor would get to a site and see what it’s like now, and then point their smart phone at that site and see an earlier version rebuilt digitally in front of their eyes and then be able to walk through it.’
Screenshot of the 3D Excelsior model