Aeolian Islands - Report


Deep water archaeological surveys off Pantelleria and the Aeolian Islands

In the month of September 2014 a campaign of archaeological surveys was conducted in ultra-deep waters of Pantelleria, Lipari and Panarea. The campaign was coordinated with the Office of the Superintendent of the Sea by Sebastiano Tusa and Roberto La Rocca with the help of Emma Salvo. Aquatic operations were conducted by Global Underwater Explorers (GUE) under its initiative "Project Baseline" and led by GUE President Jarrod Jablonski with critical support by Francesco Spaggiari and Mario Arena. GUE operations relied upon the generous support of sponsors including Brownie’s Global Logistics (BGL) and CEO Robert Carmichael. Aquatic operations were possible thanks to collaboration with the Coast Guard of Pantelleria and Lipari who directly supported recovery operations on the wreck of Panarea III. Careful documentation of archaeology sites established by the Office of the Superintendent of the Sea were made by a team of GUE technical divers, working with the latest technology provided by BGL including a 50m support vessel, two 8m support boats, twin 300m submersibles, hyperbaric chamber, full mixed gas system, autonomous underwater vehicles, BlueView Sonar and wide ranging documentation equipment.

In Pantelleria operations GUE deep divers and subs conducted operations to survey the seabed at Cala Levante, Cala Tramontana and Cala Gadir to depths beyond 200 meters, identifying areas with distribution of various types of amphorae (mainly Greek-Italic and Punic). In Lipari and Panarea survey activity was focused on the archaeological site of Capistello and on the shipwrecks of Panarea II and III. At Capistello Bay documentation built upon previous work conducted around 60m on the famous Capistello shipwreck. Early archaeological studies conducted since 1969 brought great discoveries though the wreck has unfortunately also been looted, emphasizing the importance of baseline documentation conducted during the current project. GUE operations established the presence of cargo at depths of more than 150m as well as numerous ancient anchors (some with the lead stock present). The discovery of numerous, large anchors confirms the site as a important anchorage along ancient shipping routes intersecting the Aeolian Archipelago. Exploring the deep areas surrounding the wreck identified a well preserved portion of the wooden keel at about 120 meters alongside a base and fluted shaft of a terracotta Thymiaterion (ancient incense burner) which is apparently missing the upper basin. In the same area at a depth near 80 m the project located two artifacts tied to a deflated lift bag apparently used during a failed attempt to loot the wreck of precious artifacts.

The projects greatest success came while exploring the wreck of Panarea III which was originally identified in 2010 following side scan sonar surveys in collaboration with the Aurora Trust Foundation. During this project GUE divers carried out a 3D photogrammetry survey of the wreck site and cargo contents as well as extensive photo and video graphic documentation while working at depths beyond 110m. Deep divers working in tandem with submersibles carrying expert archaeologists created a unique opportunity to systematically analyze and document the wreck site. In particular it was noticed that most of the jars are Greek-Italic but with substantial cargo of Punic Amphorae positioned in one area near what is assumed the bow. Within this section several important artifacts were located including a Catillo millstone, cylindrical vases of the type “Sombrero de Copa" (some stacked one inside the other), a collection of plates (so-called fish dishes for their use with fish paste) and a range of small plates and bowls likely used by the crew. One amazing discovery included recovery of a whole Thymiaterion (sacrificial altar) separated into two parts with a molded base bearing a Greek inscription of three letters (ΕΤΗ). The rest of the object consists of a short, smooth cylindrical column topped by a large basin. The arrangement of the cargo encourages the hypothesis that the ship is lying on its port side. This is deduced from the position of the jars and by the presence of the objects on board (plates, grinds, thymiaterion, etc.), which were likely in the hold within the bow, and were overturned and thrown almost out the main wrecksite. Upon the request of the Superintendent of the Sea, GUE technical divers recovered amphorae (one each type found in the cargo), the Thymiaterion, a few pots and pans, a jug, an olla and two vessels of the type Sombrero de Copa. The Thymiaterion is considered particularly interesting because of the Greek letters and a relief decoration on the edge of the basin showing stylized waves.

This joint mission between the Office of the Superintendent of the Sea, GUE and BGL has been a great success because it added valuable documentation for the study and protection of ancient wreck sites and due to the recovery of valuable artifacts that further enrich the already extensive archaeological underwater collection of the Aeolian Archaeological Museum of Lipari L.Bernabò Brea. These activities further support highly effective visual and teaching documentary material that will be useful to produce multimedia products aimed at the strategic activities of the Superintendent of the Sea: the spread of culture and respect for the Marine Cultural Heritage and  immense historical and cultural values of the Sicilian sea in the world. This aspect was emphasized by the Councillor for [AA BB CC and IS] Prof. Furnari during a September 15 visit of both the excavation site of Sottomonastero and the BGL/GUE operations ship, establishing the validity of cultural enrichment and survey activities conducted. Prof. Furnari has called for the creation of visual material to enhance learning in schools in the major cities and seaside villages of Sicily, but also outside the island, in order to spread the knowledge of marine cultural heritage of Sicily. It must be stressed that this activity, if performed under the contract by the Regional Administration would entail an investment of at least € 300,000 for the provision of ship, submersible and tech divers, as well as producing movies and photo shoots in high definition.
Given the very satisfactory results of this campaign, the Superintendent of the Sea Sebastiano Tusa and the President of the GUE Jarrod Jablonski decided to continue the fruitful collaboration in the coming year as part of an agreement concluded under the auspices of the Office for the AA BB CC and IS the Sicilian Region.

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3D modeling


Ancient shipwrecks provide the most direct and primary class evidence of seaborne trade and seafaring in the Mediterranean during antiquity. Their location, though, in an unfriendly environment for humans, makes their excavation very demanding in human resources and equipment. Therefore, it is essential to make the investigations cost- and effort- effective by using the best of the available tools, technical and technological. As good documentation (UNESCO, 2001) is a particularly crucial process for the post-excavation archaeological study and assessment of a shipwreck site, the use of elaborate mapping techniques is indispensable during the excavation.
Photogrammetry is a well adopted method for underwater mapping, since it is a non contact and non destructive technique. On the other hand, it is not a trivial task at all (Canciani et al., 2002; Ludvigsen et al., 2006; Drap et al., 2007; Chapman et al., 2010). By definition “Photogrammetry is the art, science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring, and interpreting photographic images and patterns of electromagnetic radiant energy and other phenomena” (Mc Glone, 2004). It is quite clear, that photogrammetry it is not a real-time or automated process. In fact most photogrammetric tasks are laborious and tedious. The much younger field of machine vision, takes advantage from computer vision algorithms and focuses on real time image exploitation for controlling a specific process or activity. Since photogrammetry’s entrance in the “digital era” it was a matter of time before embracing computer vision algorithms towards complete post- processing mapping automation.

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Archeolie 2014



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Shots!



























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Work Program



Lost Island project will start in a few days and here in the beautiful island of Lipari everything is quite ready. Now we will go back to the North for some scientific meeting and we will bring to the archipelago our big rubber boat and Helium.
Together with the Soprintendenza del Mare, Sicily region, we have made a complete and detailed  Work Program, divided by divers experience with a list of targets.
Let's give you a short summary of our program, for more info please email us at projects@gue.com

Fundy: There are several shallow water Archaeological targets that we have to survey. From a large amount of amphoras to ancient columns and capitals. We will realize a complete video survey of these artefacts. After this first phase, called observation, we will choose the best target to realize a fine scale pohotogrammetry detection in order to create a 3D reconstruction of the target. Fundy program is based on two main actions: Surevy and Photogrammetry. We will dive in shallow water, very clear and with the direct support of archaeologists. We will work not only in water but also in laboratory. In September we will have an important archaeological event, organized in the Aeolian Islands, and we will work also on the making of a video documentary that will be showed to the public during this event. Lot of work but also lot of fun.
Tech1: We will explore one of the most important archaeological submerged site of the Aeolian Islands, a roman wreck sunked at 45 mt. We will find a large amount of amphoras laying on white sand. The wreck represents a very important archaological document of ancient history and during the times it has been object of several archaological research made by famous scientists. We will have the chance to realize a complete photogrammetry survey of the wreck. There are only few images from this wreck, using hd video cameras we will realize the first video documentation of the site to get a complete and detailed overview of the wreck. Using photogrammetry and 3D software we will create a Virtual reconstruction of the wreck and once again we will work together with archaeologists to realize a real scientific work.
Tech2: for T2 and RB divers we have a big sourprise...due the importance of our work we will update only by mail...top secret.

Don't forget to bring with you your family or frineds, Aeolian Islands are a small paradise in the South Mediterranean Sea, 7 volcanic islands full of history and nature...a perfect place to Explore, Dream, Discover and have fun!
Enjoy!

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what we will do: Photogrammetry






Operative considerations

The principle of underwater photogrammetry does not differ from that of terrestrial or aerial photogrammetry, but it is necessary to take into account certain elements that may cause disturbances; in particular, the refraction of the diopter water-glass and the presence of the camera housing [39].

The specific constraints of the underwater medium (turbidity of water, presence of suspended particles) force the operators to work on a large scale, close to the objects (between 0.5 and 2 to 3 meters, depending on the water quality). This apparently constraining aspect imposes having to produce a great quantity of stereo pairs, but on the other hand it offers a very high degree of accuracy.

The important advantage of using photogrammetry in underwater surveys in comparison with the use of other techniques consists in its simplicity of implementation and the diversity of potential results (3D measurements, 3D reconstruction, orthophotography, and vector restitution).

The implementation only requires the use of a scale bar to compute the scale of the model. Moreover, if two or three synchronized cameras are used, additional equipment is not needed at the scene as the scale is computed using the calibration of the camera set. This approach also provides a relevant appreciation of the uncertainty of measurements; where, in addition, the photographs have to be taken with an important overlap. The key factor of this method is redundancy: each point of measured space must be seen in at least three photographs.

The operative advantage is related to the simplicity of the survey. Moreover, a submarine pilot can drive a remotely operated underwater vehicle (ROV) without having to undergo a long preliminary training period. This method requires little time and does not require specific personnel, thus greatly reducing the expenses in a context where time and costs of intervention are extremely high.

Camera calibration
Camera calibration in multimedia photogrammetry is a problem identified since almost 50 years [9; 23] . The problem has no obvious solution, since the light beam refraction through the different media (water, glass, air) introduces a refraction error which is impossible to express as a function of the image plane coordinates alone [37] . Therefore the deviation due to refraction is close to that produced by radial distortion even if radial distortion and refraction are two physical phenomena of different nature. For this reason, the approach described by Kwon [45] has been adopted, consisting in the use of standard photogrammetric calibration software to perform the calibration of the set housing + digital camera. This approach can indeed correct in a large part the refraction perturbation; however, it is strongly dependent on the optical characteristics of the water/glass interface of the housing. For a more rigorous approach, we can read the interesting developments made by Gili Telem, and Sagi Filin on underwater camera calibration


Automatic photogrammetry survey
The photogrammetric process is a very efficient procedure consisting mainly of three phases. The first phase is data acquisition by photographs which requires light processing. This process is non- intrusive (remote sensing), and necessitates only slightly time- consuming (only the time necessary to take pictures), and potentially a quite thorough practice. The second phase involves further data processing and is carried out in a laboratory. This phase, which is mainly automated, includes homologous point determination and pose estimation. The last phase, data interpretation and linking with domain knowledge (underwater archaeology for example) is always manual, performed by experts and very time-consuming.

SIFT algorithm is often used to determine the homologous points
[39, 40] and recently the FAST [41] algorithm is applied. Then the pose estimation process from relative orientation of stereo pair is obtained by the Stewenius algorithm [42; 46; 60] . The SBA open source software by Manolis Lourakis [51] and Noah Snavely [58] is applied for the global bundle adjustment. Finally several approaches are proposed for surface densification PMVS by Ponce and Furukawa [54; 55] . For a good overview of these techniques it is possible to refer to these paper [64] [40] . In our application, we chose three tools to solve this problem and we have developed some of them. We also develop bridge between them in order to take benefit of the best of each of them.


Underwater 3D survey merging optic and acoustic sensors
Optic and acoustic data fusion is an extremely promising technique for mapping underwater objects that has been receiving increasing attention over the past few years [53]. Generally, bathymetry obtained using underwater sonar is performed at a certain distance from the measured object (generally the seabed) and the obtained cloud point density is rather low in comparison with the one obtained by optical means.

Since photogrammetry requires working on a large scale, it therefore makes it possible to obtain dense 3D models. The merging of photogrammetric and acoustic models is similar to the fusion of data gathered by a terrestrial laser and photogrammetry. The fusion of optical and acoustic data involves the fusion of 3D models of very different densities – a task which requires specific precautions [44; 56] .

Only a few laboratories worldwide have produced groundbreaking work on optical/acoustic data fusion in an underwater environment. See for example [38] and [41] where the authors describe the use of techniques that allow the overlaying of photo mosaics on bathymetric 3D digital terrain maps [52] . In this case we have important qualitative information coming from photos, but the geometric definition of the digital terrain map comes from sonar measurements.

Optical and acoustic surveys can also be merged using structured light and high frequency sonar as by Chris Roman and his team [50]. This approach is very robust and accurate in low visibility conditions but does not carry over qualitative information.

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how to get there


AIRPORT
Fly to Naples or to Palermo.

AIRLINES FROM THE UK
British Airways (0870 850 9850; www.ba.com) flies from Gatwick to Naples. Monarch (0870 040 5040; www.flymonarch.com) flies to Naples from Birmingham, East Midlands, Glasgow and Manchester. Ryanair (0872 246 0000; www.ryanair.com) flies from Stansted to Palermo. Easyjet (0905 821 0905; www.easyjet.com) flies from Stansted to Naples.

BY BOAT
Ferries to the islands are operated by SNAV (00 39 081 428 5111; www.snav.it) from Naples; Siremar (00 39 090 928 3242; www.siremar.it) from Milazzo; and Usticalines (00 39 090 924 9199; www.usticalines.it), from Milazzo and Palermo.

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Pictures by GUE and Caludio Provenzani. Powered by Blogger.