The Virtual Museum Underwater Malta
Over 7,000 years of human history are reflected in and on the landscape of Malta, and recent offshore surveys have sought to answer the question of whether this is also mirrored on the seabed surrounding the islands. What is undeniable however, is that Malta’s long and complex history has left an indelible mark on the seabed, and the concentration of underwater cultural heritage is unique, both in terms of quantity and quality. Due to the varied historical contexts Malta’s UCH can be considered as an international cultural asset. The UNESCO Convention on the Protection of the Underwater Cultural Heritage places public outreach at the centre of best practice for activities directed at submerged heritage. The challenge that heritage managers face is how to communicate and share these historic time capsules with the wider public. The reason for this is simple – the physical barrier created by the sea has resulted in out of sight and out mind outlook amongst the wider public - often unaware of the rich and unique heritage located out of reach on the seabed. Rapidly evolving digital technologies have been integrated into underwater archaeological practices at a swift rate over the past decades, a direct result of the challenges presented by elements such as depth, temperature, visibility and currents. Digital technologies were initially used to record and document underwater sites, however, it was soon realised that the resulting 3D reconstructions had great potential for public outreach purposes. From a scientific perspective, the 3D models act as baselines from which the condition and continued preservation of these sites can be monitored. This is a particularly valid consideration when taking into consideration, for example, the polluting potential of metal wrecks, or the rapidly deteriorating character of wooden remains. The digital models also have public outreach and access considerations, and today, it is considered to be best practice to integrate virtual experiences into the management process. Therefore, through a rising awareness of the capability of 3D photogrammetry to narrow the gap between the non-diving public and the seabed, the idea for Underwater Malta, a virtual museum, was born. The main aim behind this was the creation of a widely accessible space where members of the public can explore multiple underwater cultural heritage sites as 3D reconstructions or through virtual reality. What needs to be noted is that the launch of a submerged site on the Underwater Malta platform is the last step in a series of complex processes, beginning with geophysical surveys, diver reconnaissance and 3D survey dives, to the processing of datasets and the final research behind the textual information. A unique feature of the majority of Malta’s underwater cultural heritage sites are their location beyond the 40-metre recreational diving limit. The sites currently presented on Underwater Malta range in depth from 3 metres to over 120 metres. Whilst this characteristic may have presented a barrier to diver access in the past, today, advances in diving technology such as mixed gas and closed-circuit rebreather diving, have broken through this barrier. Dives are only planned to those sites that are considered reachable, with safety considerations taking precedence. It must be mentioned that planning such deep-water survey dives is an enormous undertaking, involving the collaboration of the whole team, divers and surface support. The depth at which many sites are located necessitate decompression diving, and the team limit themselves to approximately 20 minutes of bottom time, leaving a limited window of operating time to capture data. The project team descend to the depths using rebreather technology, and dive teams are always composed of a cameraperson, a light operator and a safety diver. To provide some perspective on the volume of data gathered and processed, a medium-sized aircraft wreck is covered with 1500-2500 images, and approximately eight hours of total processing time. A medium-sized shipwreck requires over 8000 images, and a processing time of at least 36 hours. A large shipwreck will require upwards of 10,000 images and require up to 72 hours of processing time. This does not include the time spent diving the site, where multiple dives often need to be carried out to capture the wreck site in its entirety. Structure from Motion (SfM) photogrammetry is the method used to create the 3D reconstruction presented on the virtual museum. Powerful underwater lights, providing anything from 40k to 80k lumens and full-frame mirrorless cameras, generating 24-megapixel still images, are used to systematically record the sites. Water visibility around the Maltese Islands is considered to be very good, however, the distance of the camera to the object being recorded is generally kept within 2 metres, which allows the capture of high-quality texture. In situations where visibility is minimal, the distance to the object is minimized, which increasing the numbers of images required. The cameras are set to take on-to-two stills per second, and a short exposure time is integral to the ability to cover a deep-water site in its entirety in the limited time available. This is in stark contrast to shallow or terrestrial sites, making it a defining characteristic of the method for deep-water sites. One of the main elements of the Underwater Malta website is the broad set of digital assets that are presented to public. The captured data is used to produced; (1) a 3D model that is simple to navigate and fast to load, supplemented by annotations and textual information, (2) a video flythrough of the wreck, taking the viewer through a fixed path that is intended to simulate a diving experience, (3) a full 3D model that can be zoomed, spun around and examined at a detailed level, allowing visitors the option to explore the wreck site through virtual reality technology in a 1:1 scale, (4) an artists impression that is used to present the wreck site on the landing page of the website. Video footage of divers exploring the wreck as well as high-resolution imagery is also available for each wreck site. The design of the website itself revolved around the requirement to create a user-friendly space that provides an interactive experience to all levels of digital fluency. Curation and promotion are an integral part of virtual museum. The background research behind each site revolves around site generic and site particular information. The aim here is to provide visitors with an overview of features specific to the general wreck type as well as to those elements that define the wreck site, such as depth, marine environment and condition. Currently there are 14 sites presented on Underwater Malta, ranging in date from a 2,700-year-old Phoenician shipwreck to various aircraft wreck sites and shipwrecks dating to the Second World War and Cold War. More sites are scheduled to be added to the virtual museum in the coming weeks and months, furthering the aim of raising the profile of Malta’s underwater cultural heritage and allowing the public to dive into history. The sustainability of the Underwater Malta project is reliant on its ability to attract visitors, with the ultimate aim of raising awareness on the underwater cultural heritage of Malta. Since its launch end of June 2020, the virtual museum has attracted approximately 35,000 visitors – mainly from Malta, United Kingdom, United States and continental Europe. It is the aim of the project to continue virtually presenting Malta’s underwater cultural heritage, curating a space where the public can virtually dive into history.