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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Secca di Capistello wreck

 

The real excavation of the wreck took place in 1977 under the direction of Michael Katzev and Donald A. Frey (INA) with the technical support of Sub Sea Oil Co.. But sometime earlier a team of DAI (Deutsche Archäologische Institut) started the survey of the wreck, but it was stopped by the tragic death of two archaeologists.
The excavation of 1977 was the first deepwater archaeological excavation. The wreck lies at - m 59. To excavate the ship properly, saturation diving had to be done. Divers breathed a helium and oxygen mixture. Dives were 5, 7 and 9 days. This meant that the divers had to go through 38 hours decompression at the end of their shift.
On the whole, divers worked on the wreck for two hours. There were teams of four, two diving in the morning and two in the afternoon. For safety reasons, one diver always monitored the other from the on-site diving bell. For further safety, there was a continual diver-surface com and CCTV. However, there was a lot of interference.
The hull was the major artefact to be uncovered in the 1977 excavation. Of the hull, around 6 sq. m was exposed during excavation with the further indication that more lay under a layer of undisturbed sand and amphorae. The details of the uncovered hull are as follows: The main section featured eight to ten exposed strakes on which eight frames were located and overlain with three interior planks. The frames were moulded 10cm and sided 16cm. The strakes are given an average measurement of 20cm in width and 4.5cm in thickness. These were joined together by pegged mortise-and-tenon fastenings that were widely spaced - between 16cm to 18.5cm. Mortises averaged 5cm to 6cm deep.
A large interior timber was uncovered in the excavation running longitudinally across six frames. Measuring 30cm wide and 6cm thick, the timber may have acted as a clamp to strengthen the hull from the inside. Two other interior timbers were recovered which could have been the remains of ceiling planking. A wooden pole 7cm in diameter lied parallel to the main timber but was unattached to the hull, it's purpose remains unknown.
Brushwood was found beneath the amphorae and spread over the inside of the hull. The interior of the hull was coated with a thin layer of a dark tarry substance which had to be removed by the divers to get to the tenon peg outlines and the seams between the strakes. A number of copper and iron nails were also found, one complete measuring 15cm in length and retaining its original clenched shape.
The Capistello ship, indicated by the size of the hull recovered and by that remained buried or lost, is believed to be bigger than the Kyrenia ship of roughly a century earlier. The Kyrenia measured 15m by 5m. The Capistello is dated to the fifth century BC, 100 years prior to the Kyrenia.
The Capistello wreck was a small freighter carrying amphorae and Campanian ware, a fairly normal cargo for a Mediterranean freighter to carry. The Capistello wreck was dated to the IVth century, a century later than the Kyrenia.
The building technique of the ship falls into the transitional period of Mediterranean boatbuilding as shown by the Kyrenia and St Congloue ships. The Capistello wreck has mortise and tenon fastenings, but they are widely spaced and do not give the hull strength and integrity. This is carried by the frames, which were moulded to fit the hull. They are fastened by copper nails to the hull, the nails clenched over on the inside. The frames were a pattern of floor timbers and half-frames alternating with each other. Additionally, the excavation showed a logitudinal timber running over the frames. It was 30 cm wide, and was used as a stringer to further strengthen the hull.

 

 

Bibliography
Blanck H., 1978, Der Schiffsfund von der Secca di Capistello bei Lipari. Mitteilungen des Deutschen Archaologischen
Instituts, Romisch Abteilung 85. Mainz am Rhein.
Frey D.A. & Hentschel F.D. & Keith D.H., 1978, Deepwater archaeology. The Capistello wreck excavation, Lipari,
Aeolian Islands. IJNA, 7.4: 279-300.
Frey D.A. #et al#., 1979,L'archeologia sottomarina a grande Profondita: gli scavi di Capistello.Sicilia Archeologica,
12.39. (Trapani)
Kapitan G., 1978, Exploration at Cape Graziano, Filicudi, Aeolian Islands, 1977. IJNA, 7.4: 269-277. Picozzi S., 1979, La nave di Capistello. Il Subacqueo, 7.70.
Sebastiano Tusa

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Project's Targets - Wrecks & Cargoes in the Aeolian Archipelago

The sea-beds around the Aeolian Archipelago consititute an extraordinary archaeological goldime: there abohnd wrecks or cargoes - in many cases this latter definition is the most appropriate since no traces of the ship remain. These ships were wrecked in tracts of sea which were very dangerous especially when crossed during a storm (such as the shoals of Capistello in Lipari and Capo Graziano in Filicudi, and the rocks of the Formiche at Panarea). There are also accumulations of materials of various epochs which were dumped in ports that have now disappeared owing to changes in the coastline over the centuries, and various sporadic finds.
Here is the list of the main wrecks of the Aeolian Islands Archipelago:
1. Cibatti-Signorini wreck in Pignataro di Fuori in the bay of Lipari below Monte Rosa: one of the oldest naval cargoes of the Mediterranean, composed of impasto pottery of the Early Bronze Age belonging to the early phase of the Culture of Capo Graziano (beginning of II Millenium B.C.)
2. Wreck near the orck of Dattilo at Panarea: a cargo of black burnished pottery, possibly of Italiote fabrication (that is, from Greek settlement in Southern Italy), of the beginnning of the IV century B.C.
3. Wreck F from Capo Graziano at Filicudi: Italiote amphoras and black burnished pottery probably of Aeolian fabrication. First half of III century B.C.
4. Wreck from the shoal of Capistello, off the south-east coast of Lipari: Italiote amphoras and black burnished Campana A pottery of Neapolitan fabrication, or at any rate Campanian. Beginning of III century B.C.
5. Roghi Wreck from Capo Graziano at Filicudi: the first wreck to be discovered in the Aeolians (1960). Cargo of amphoras of the Dressel I A type, black burnished Campana B pottery of Central Italian fabrication and plain pottery, II century B.C.
6. Alberti wreck from the Formiche of Panarea: a cargo possibly from Campania of amphoras mainly of the Dressel 2/4 type, with the remainder Dressel 43/Cretan 4. Second half of I century A.D.
7. Wreck of late Imperial Roman age from Punta Capazza between Lipari and Vulcano: ignots of tin probably of Spanish provenance, blocks of sulphur of arsenic from Vulcano.
8. Cargo of late meiaeval glazed pottery from the Formiche of Panarea.
9. Filicudi E wreck or Cannons Wreck: Three bronze cannons from Spanish warship probably sunk in an engagement with the French fleet od Admiral Vivonne who came to the aid of Messina which had risen against the Spanish government in the famous revolt of 1675.

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Our new Baby

We went to GEI Laboratory to plan the ROV operation program. With the supervision and support of the University of Florence, Robotic department, we will use the Pollux III to realize a photogrammetry survey of the 4 Roman Wrecks of Panarea Islands.
The Pollux can dive at 400 mt of depth mounting cameras, hydro sensors, sonar and multibeam echoesounder a perfect buddy for our research project.
Enjoy!

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Aeolian Islands - The Escape guide

The Aeolian Islands:

Smouldering volcanoes, bubbling mud baths and steaming fumaroles make these tiny islands north of Sicily a truly hot destination. 

Astonishingly beautiful and extremely varied, the seven islands and various uninhabited islets of the Aeolian archipelago were designated a Unesco World Heritage Site in 2000. Their volcanic origins left a dramatic legacy of black-sand beaches, smouldering craters and splintered, rocky coastlines. Island-hoppers can discover their individual charms: from the spartan conical Alicudi, where donkeys are the only form of land transport, to the international jet-set playground of Panarea.
North of Sicily in the Tyrrhenian Sea, the archipelago was named after Aeolus, god of the winds, by Greek settlers. This has been a volatile part of the world ever since Filicudi, the first land mass, emerged from the sea 600,000 years ago. There are two active volcanoes, Stromboli and Vulcano, and volcanic activity of some kind, whether steaming fumaroles or thermal waters waiting to be tapped, on most of the other islands. Winter storms see the islands cut off for days.
Like many coastal communities, the islands, with a total population of 10,000, have very different characters depending on the season. The head count swells to 200,000 in summer: ports fill with yachts; bars and beaches overflow with the very beautiful and the very wealthy. In August, the rich and famous sail in to Panarea on their multi-million-euro yachts to occupy villas or €500-a-night hotel rooms, and they don't do it quietly. This is easily the most fashionable and expensive of the islands, but there is more variety in the Aeolians than a quick jaunt around Panarea's shores in peak season might lead you to believe.

Lipari

The largest of the Aeolian Islands, Lipari is also the only one with a sizeable town, a substantial year-round population and much in the way of industry. Pumice quarries have taken huge bites out of the mountains, though mining has recently been banned and there are plans to create a 'geo-park' with an eco-museum and thermal baths. Although the town has its attractions (the fortified acropolis, some flower-hung alleys, the pretty harbour of Marina Corta), it's not a very sophisticated place. Gaudy sarongs, mass-produced jewellery and overpriced tourist menus compete for visitors' attention with hardware stores, chandleries and the archipelago's main supermarket.
The coast around here is wild, rocky and, best of all, undeveloped, with splintered rocks offshore and extraordinary views. It's inaccessible by car, but you can reach it on foot at Valle Muria, where there's a beach (and, in season, boats to and from the port), or at Punta delle Fontanelle.
The coastal highlight is the footpath along the coast between the Terme di San Calogero and the kaolin quarry at Bagnosecco, where the surface of the creamy white kaolin has been stained indigo, violet, orange, mustard, blue and verdigris by emissions from steaming sulphurous fumaroles.

Vulcano

Although awash with eminently marketable novelties (a constantly smouldering volcano, the chance to wallow in warm mud baths and swim above bubbling mid-sea fumaroles), Vulcano has been developed in careless fashion. The little town has the unfinished look of a Western film set, and the promontory of Vulcanello is studded with bland luxury hotels. There's also nowhere decent to eat, though this isn't necessarily a bad thing: the pervading rotten-egg stink of sulphur may already have killed your appetite.
The path up to the crater begins about a kilometre out of town on the road to Gelso, marked by a sign warning of the dangers of inhaling volcanic gases. The climb (access €3) takes less than an hour, though you'll need hiking boots to cope with the slitheriness of the ashy track.
The Fanghi di Vulcano (mud baths) and offshore fumaroles are a couple of minutes' walk from the port. Don't wear contact lenses, don't let kids play in the mud - and don't be surprised if you stink of sulphur for a couple of days afterwards. Alternatively, you could head to the rather more genteel Oasi della Salute spa, which has three thermal hydromassage pools and a beauty centre (00 39 090 985 2093, closed October to March).

Salina

Twin-peaked Salina is the greenest of the islands, famous for its starring role in the 1994 film Il Postino. Santa Marina Salina, the main port, is notable for its long, traffic-free main street, where chic boutiques and down-to-earth food shops occupy the ground floors of the substantial 19th-century houses built by those who made their fortune selling sweet Malvasia wine to the British. Most of these entrepreneurs lost their fortunes in 1890 when phylloxera destroyed 90 per cent of the vines and prompted a mass exodus to Australia (and the start of that country's wine industry), but viticulture in the area has been revitalised. Local wines can be tasted at vineyards such as Fenech at Malfa (00 39 090 984 4041; fenech.it), Caravaglio at Capofaro (00 39 090 9843420) and D'Amico at Leni (00 39 090 980 9123).
The story of the island and of the emigration are vividly evoked in two tiny folk museums, the Museum of Emigration in Malfa (00 39 090 984 4008) and the Ethnographic Museum in Lingua (090 984 3128). However, you are more likely to want to spend your time in Lingua lying on the stony beach or lingering over a granita at the famous Da Alfredo bar.
Spring and autumn are the best times to climb Monte Fossa delle Felci, the highest peak in the archipelago (summer being too hot and winter prone to sudden storms). The best way to see the south of the island is to take a bus to the village of Leni then follow a series of mule tracks down the mountain to Rinella, where there's good swimming from a black-sand beach.
If you can, try to be at Pollara, the setting for Il Postino, at sunset. A simple trattoria, Il Cappero, and a hotel, La Locanda del Postino (00 39 090 984 3958; www.lalocandadelpostino.it), have recently opened here, but there are no shops or bars out of season.

Panarea

If you aren't a member of the rich and famous posse who hang out at painfully cool Hotel Raya or take their sunset aperitivi at the Bridge Sushi Bar in the port, Panarea in August is probably best avoided. But if you want to swim, walk or take boat trips around what is probably the most beautiful of the Aeolian Islands, come in spring or autumn. The hotels are generally pretty expensive, but Pippo and Maria (00 39 090 983060) have perfectly nice rooms to rent in a quiet part of the village.
Be sure to take the 40-minute walk to the dark gold sandy beach of Zammarà and the magnificent bay of Cala Junca beyond, at the foot of a promontory topped by the foundations of Bronze Age huts. A 20-minute walk to the other side of the village brings you to the beach of Calcara, where fumaroles steaming through sulphur-stained rocks led ancient Panareans to believe it was an entrance to the Underworld. A boat trip out to the offshore islets is another must. The formation and colours of the rock on each are unique. Below tiny Basiluzzo, when the sea is calm and clear, you can see the remains of a Roman port and clamber up to the ruins of a Roman villa; nearby Lisca Bianca has submarine fumaroles bubbling at the surface of the sea, little sandy beaches and cliffs that have been stained yellow.

Stromboli

When Roberto Rossellini and Ingrid Bergman arrived on Stromboli in 1949 to shoot Stromboli, Terra di Dio, there was no hotel. A local teacher, Domenico Russo, provided Bergman with a house and secured the house next door for Rossellini, so the two could meet without compromising their reputations. After the film was released and tourists began to visit Stromboli, Russo opened the island's first hotel.
These days, it's the volcano that attracts most of Stromboli's visitors. The vast majority arrive brandishing alpenstocks and looking like hopefuls for the Foreign Legion. But if you're in reasonable shape, all you need to reach the top is trekking boots, a torch, a warm jacket, some water and €30 for your a place on a guided walk, which takes two hours and is timed so that you arrive on the summit at sunset.
The best beaches on Stromboli are the little coves of black sand tucked into lava crags along the coast at Piscità, from which there are fine views of the islet of Strombolicchio.

Filicudi & Alicudi

The tarmac road that connects the small settlements on Filicudi gives a false impression of the island. Villages that seem far apart are just a few minutes' walk from one another along the old mule tracks that cut through the terraces, and the island as a whole is best seen on foot or by boat. With a seabed that's home to scores of ancient shipwrecks, Filicudi offers some interesting diving. If you don't dive, take a boat trip around the island to see the hidden sea grotto, scene of a candlelit festival every year on 15 September.
The port is the least attractive part of the island. Head instead for the tiny fishing port of Pecorini a Mare, where there's little to do except eat good food, beachcomb (Filicudi has some of the best shells in the archipelago), and walk up to the clifftop belvedere to watch the sun set over the rock known as La Canna. Alicudi, by contrast, is an uncompromising cone rising from the sea, and can be scaled only by heaving yourself up steps a giant's stride high. Most visitors love it or hate it. There are just 80 year-round inhabitants and, it's said, most of them loathe the sight of each other. Rumour, superstition and ghost sightings abound, as does the conviction that some Alicudari are blessed with the power to divert cyclones.
 

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Aeolian Islands Paradise

Seven islands in the Tyrrhenian sea in the province in Messina, all of volcanic origin: Alicudi, Filicudi, Panarea, Stromboli, Salina, Lipari and Volcano, the nearest island to Milazzo.
Through this site some of the tourist operators of the receptive-hotel sector propose their structures to the tourists to help them to orient among the numerous ones - and valid - offered of rental houses , hotels, hotels, restaurants, services and other. The Aeolian Islands (italian Isole Eolie) are a volcanic archipelago in the Tyrrhenian Sea north of Sicily. They are a popular tourist destination in the summer, and attract up to 200,000 visitors annually.The largest island is Lipari, and tourism marketing often names the entire archipelago the Lipari Islands because of the ease of pronouncing Lipari compared to Aeolian. The other islands include Vulcano, Salina, Stromboli, Filicudi, Alicudi, Panarea and Basiluzzo. The town of Lipari has about 11,000 inhabitants. Vulcano is famous for its fango (mud) baths.

TRAVEL (how to arrive)

There are frequent car ferries and much quicker hydrofoils from Milazzo and Messina on Sicily , and from Reggio di Calabria on the mainland, to and between the islands. Most call first at Lipari, and then proceed to the other islands. Ferries are frequent in summer, with fewer during spring, autumn and winter and a reduced service year-round on Sundays.
For timetables see SIREMAR, Ustica Lines and NGI. It is important to check the timetables in advance, and to allow plenty of time for connections, as boats can be early or late.
A few car ferries a week also continue on to Naples (see SNAV ) and during the summer hydrofoils run to and from Naples, Cefalù, Palermo and Messina.
The Aeolian Islands are quite remote, which is part of their appeal. No air travel is available to the archipelago, except for the very expensive helicopter service which runs during high season from the Catania airport. For more information see Air Panarea. Most international travellers, then, will arrive at the airport of either Palermo or Catania airport in Sicily, or Reggio di Calabria, across the straits of Messina on the mainland.
Although the Reggio airport is relatively near the port, boats from Reggio are infrequent. Likewise, only a few ferries per day run from Palermo during high season, and the airport is far from the city. These ports are best used by the traveller who is already in Italy, as is Naples, a much longer boat trip that is convenient for travelers arriving by plane or train in Naples from points north. For the traveller arriving directly from abroad, numerous budget airlines have routes from around Europe to Catania. From there, one can take the train, or an express bus, to Messina, connecting to a boat; or, at Messina, one can connect to a second train or bus to Milazzo, which has by far the most boat departures. Although it is convenient to change trains in Messina, the Milazzo train station is a few miles from the port. On the other hand, the bus from Catania arrives at the train station, while the bus for Milazzo departs from a separate bus station a few blocks away. Ask for help at the information booth outside the train station. Buses departs from Catania airport to Milazzo. One may wish to spend the first night in Lipari, with its charming town, and then depart for the outlying islands. As another alternative, the car rental agencies have special deals allowing the traveller the use of a car one-way from Catania to Milazzo - inquire in advance as these deals may not be available without reservations. The car rental agencies in Milazzo are a few blocks from the port.

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