The photogrammetry of underwater cultural heritage in South-West of Madagascar

The photogrammetry of underwater cultural heritage in the maritime territory of Tsifota farming township, South-West of Madagascar: Winterton (1792), Nossa Senhora do Carmo (1774) and Surprise (1885).

Ship history

Winterton, an English ship that was launched in 1782. Captained by Dundas, this ship left England on May 2, 1792 to pass Madras bound for Bengal. He sailed with around 280 people, including 10 women in addition to his crew, and also carried a cargo of 300,000 silver coins, or about 8 tons of silver. From the Cape of Good Hope, he made his way through the Mozambique Channel because of the winds which were not favorable to the crossing in eastern Madagascar. The captain intended to reconnoitre this island in the vicinity of Saint-Augustin, but contrary winds prevented him. On the night of August 19, 1792, following a misinterpretation of its position, the ship climbed onto the reef just in front of the current Salary Bay hotel, in calm seas. Despite the usual maneuvers, in particular the anchoring of an anchor offshore to try to tow and the lightening of the ship, they were unable to free themselves. As usual, the swell rose and the ship was torn to pieces, resulting in the death of many passengers in appalling conditions. Many accounts of this sinking have been published by survivors. The survivors were taken in by King Baba in Tuléar.

Nossa Senhora do Monte do Carmo, it is a ship of the Portuguese Royal Navy was put into operation in February 1760 and having been shipwrecked in 1774. After having traveled the Atlantic Ocean for ten years, under the command of Captain Hermogénio de Sousa de Campelo, this ship was sent from the Goa to India to bring artillery. In August 1774 he approached the west coast of Madagascar. On August 8 at 5:30 a.m., this ship landed on the north Salary reef. During the day, the crew and passengers were evacuated to nearby land without difficulty. The ship remained on the heels of the North Salary reef and ended up breaking up. Then, the swell and the currents scattered the wrecks following a cone of dejection. In 1984, Robert Sténuit found this ship with the help of local people and carried out archaeological excavations during his mission. This team had not prioritized the archaeological aspect, it was motivated by the rescue of the values ​​of the boat. However, in the end, she did not find much because the vezo had already passed many times on this site and took everything they found to have values.

Surprise which was sunk in 1885 is an American ship built in 1866 in Boston. On August 16, 1885, she sailed from New York harbor with a cargo of 16,500 barrels of kerosene and set out for the international sea route through the Cape of Good Hope in South Africa to Zanzibar and Chittagong, under orders of Commander Cyrus Averill, bound for Bombay. As he sailed up the Mozambique Channel, he hugged the west coast of Madagascar to dodge a strong southerly current and take advantage of more favorable onshore winds. With fine weather and bright moonlight at 1:30 a.m. on November 21, 1885, Captain Cyrus Averill estimated that Surprise was about 30 miles from the coast. He took a broadside towards the coast and went down to bed, ordering him to be awakened when the land was sighted. Around 4 a.m., the ship suddenly touched down and was still moving forward. Captain Averill had rushed up and ordered the helm to be pulled down the course, but the ship stopped almost immediately afterward, it landed in calm seas on the reefs of Salary North. Eventually, the captain left the ship with his daughter and the rest of the crew. Located in a channel between two reefs, Surprise currently rests at a depth of 17 m.

Photogrammetry mission

From May 07 to 15, 2022, a photogrammetry mission was carried out in collaboration with the Maritime Archeology Trust team as part of the Rising from the Depths innovation research project entitled: Implementation of network system by fishermen’s community actor for the marine cultural heritage survival. Case of the farming township of Tsifota in Southwest of Madagascar. The main objective of this mission was to collect digital data of underwater cultural heritage in order to promote it for tourism development.

The British underwater archaeologist divers from the Maritime Archaeology Trust: Garry Momber and Bradon Mason as well as the team from the Marovany association: Rabekoto Andrinjarisoa Heritiana and Solondrainy Nestor dit Bay, were accessed to the underwater archaeological sites in the mornings from the boat of Fred Lucas of Salary Diving using the diving equipment of this center. In addition, the Maritime Archaeology Trust’s photogrammetry devices were used to obtain photos and video of the sites as well as the wrecks. These images show the locations and number of materials from wrecked ships that are strewn about underwater spaces. Archaeological studies have been carried out to confirm the extent of each site and the wrecks observed. There was also data processing to have 3D photos of sites and wrecks. Below is one of the photos the team took. It is a cross ink of Nossa Senhora do Monte do Carmo. The best site that has a lot of cannons and a romantic site for the diving enthusiast.

Photogrammetry training and practice

Training on the theory and practice of photogrammetry was carried out each afternoon for the Marovany association team in this project. It is an introduction to photogrammetry, equipment for photogrammetry, survey planning for photogrammetry, data processing with Metashape and Meshroom software, optimizing the production and publication of results, and others.

Despite the inability of the Marovany association’s computer for 3D photo processing on the free Meshroom software, the image processing was well done with Metashape from Agisoft and published on the association’s Sketchfab.

The presentation of the results was made so that the fishing communities know the situations of the underwater sites. Tourist operators, village leaders from each fokontany and notables from the village of Salary Nord I have attended. They appreciated very much this act and the activities that were carried out by the videos and especially the processing of 3D images. Results will be published online so that the whole world appreciates the value of underwater cultural heritage for sustainable development.

Questions, suggestions and comments are always welcome, email me at andrinjarisoa@gmail.com