Tagarchief: 3D photogrammetry

The SMS Emden

Lees hier de blog in het Nederlands.

On Tuesday we left Christmas Island and went to the Cocos-Keeling Islands. The Cocos-Keeling Islands are a group of 27 coral islands that are located in the Indian Ocean approximately 2700 km north-west of Perth. The main islands form a typical horseshoe-shaped atoll surrounded by a coral reef. Each island has rough coral beaches to seaward and sandy beaches on the lagoon side. The islands are low lying and most are thickly covered with coconut palms. Wildlife on the islands consists mainly of seabirds. Just like on Christmas Island, land crabs are common on all islands and the surrounding reefs support a diverse range of corals, fish and other marine organisms.

Surveying again!
Surveying again!

After the team unpacked and setup base at ‘The Castle’, we started doing a magnetometer survey again. After that we snorkeled the Phaeton wreck. The Phaeton was built at Sunderland (UK) in 1868 as a composite ship (timber planking over iron frames) and was 46 meter long. It wrecked in Cocos in 1889 while carrying a cargo of copra from Cocos Island back to Europe. At about half past five on the morning of the 25 September the Phaeton was discovered to be on fire. The fire force pump was in the area of the fire and could not be reached safely and the vessel could not be saved. To avoid blocking the entrance to the lagoon, the Phaeton was run aground in its present position, broken up and salvage. We hope to make a 3D photogrammetry model of the remains of the Phaeton using photos and video we made.

North Keeling and the SMS Emden

Besides looking for the Fortuyn and the Aagtekerke one of our objectives here is to properly record the SMS Emden. This German light cruiser was at her home port of Tsing-Tau in China at the outbreak of World War 1. She was on her way on the 6th of August with orders to her captain Von Muller to destroy as much allied ships as possible. Her rampage in the Indian Ocean was brief but spectacular as she managed to sink 15 merchant ships, a Russian cruiser and a French destroyer in less than two months!


Early on the morning of November 9th the Emden appeared off the Cocos-Keeling Islands, and sent a landing party of three officers and forty-two men ashore to dismantle the cable station that was there. While they were at work the Australian cruiser HMAS Sydney arrived. Although the Emden’s gunnery was excellent and her opening salvo scored a direct hit on the Sydney, she was no real match for the larger ship. Within two hours, she was out of action, and hopelessly disabled. It was then about noon, and the Sydney left her to chase a captured merchantman which had been acting as an escort for the Emden. On her return, about 4.00 pm, she found the Emden still flying her colors, but unable to move. The Sydney signaled to her to surrender, but received no answer, and finally fired several further rounds at her. Only then did von Muller strike his flag. By this time the Emden was blazing furiously amidships, and in an attempt to save as many of his crew as possible he drove her on to the reef fringing the south coast of North keeling.

North Keeling is located approximately 27 km from the main group of islands and is thus quite remote and not a lot of people go there. It was really special to be able to dive there and see the remains of the vessel, because although it has been partly salvaged there is still a lot left of it as you can see on the photos we took. One of our team members even went on the island with Triss from Parks Australia, to document the remains of the vessel on land! Just as with the Phaeton we hope to make a nice 3D photogrammetry model of the ship to get a good overview of the site. We also documented what still remains of the vessel and did a corrosion measurement.

In the following days we will continue our survey for the Fortuyn and the Aagtekerke. We will keep you updated as good as we can with the limited internet access we have here..

 

De SMS Emden

Read this blog in English!

Op dinsdag verlieten we Christmas Island en gingen we naar de Cocos-Keeling Islands, een groep van 27 koraaleilanden in de Indische Oceaan zo’n 2.700 km ten noordwesten van Perth. De hoofdeilanden vormen een atol met een typische hoefijzervorm dat omringd is door een koraalrif. Elk eiland heeft ruwe koraalstranden richting de open zee en zandstranden aan de lagunekant. De eilanden zijn laag en de meeste zijn dicht begroeid met kokospalmen. Wild op de eilanden bestaat voornamelijk uit zeevogels. Net als op Christmas Island komen hier op alle eilanden veel landkrabben voor en het rif rond de eilanden herbergt allerlei koralen, vissen en andere mariene organismen.

Weer aan het meten!

Zodra het team alles had uitgepakt en zich geïnstalleerd had in ‘The Castle’ gingen we opnieuw metingen uitvoeren met de magnetometer. Daarna snorkelden we naar het wrak van de Phaeton. De Phaeton werd in 1868 gebouwd in de Engelse stad Sunderland; het was een zogeheten composietschip (gemaakt van houten planken die op een stalen frame worden bevestigd) met een lengte van 46 meter. In 1889 leidde de Phaeton schipbreuk bij Cocos, terwijl het een lading kopra van Cocos Island terug naar Europa vervoerde. Op 25 september ontdekte men rond half vijf ‘s ochtends dat de Phaeton in brand stond. De brandbluspomp bevond zich in het gedeelte waar de brand woedde en kon niet op een veilige manier worden bereikt, met als gevolg dat het schip niet gered kon worden. Om te voorkomen dat de toegang tot de lagune werd geblokkeerd, liet men de Phaeton op haar huidige plek vastlopen en werd het schip opengebroken en geborgen. We hopen dat we een 3D-fotogrammetriemodel van de resten van de Phaeton kunnen maken met behulp van de foto’s en video die we gemaakt hebben.

North Keeling en de SMS Emden

Naast het zoeken naar de Fortuyn en de Aagtekerke is een van onze doelen hier om de SMS Emden goed vast te leggen. Deze Duitse lichte kruiser lag in zijn thuishaven Tsing-Tau in China toen de eerste wereldoorlog uitbrak. Het schip voer op 9 augustus uit, met orders voor kapitein Von Muller om zo veel mogelijk schepen van de geallieerden onklaar te maken. Deze kruiser voerde een korte maar spectaculaire strijd in de Indische Oceaan: de Emden slaagde erin om in minder dan twee maanden tijd vijftien koopvaardijschepen, een Russische kruiser en een Franse torpedobootjager te vernietigen!

In de vroege ochtend van 9 november doemde de Emden op voor de kust van de Cocos-Keeling Islands; drie officieren en 42 manschappen werden aan land gestuurd om het telegraafstation op het eiland te ontmantelen. Terwijl ze daarmee bezig waren, kwam de Australische kruiser HMAS Sydney aan. Hoewel de Emden over een uitstekend geschut beschikte en het schip met het openingssalvo de Sydney meteen wist te raken, was het toch geen partij voor het grotere schip. Binnen twee uur was de Emden uitgeschakeld en lag het schip hopeloos in puin. Dat was rond het middaguur en de Sydney liet de Emden achter om een buitgemaakt koopvaardijschip, dat als een escorte voor de Emden had gefunctioneerd, te pakken te krijgen. Toen de Sydney rond vier uur ’s middags terugkeerde, hing de vlag van de Emden nog in de mast maar was het schip niet in staat om te varen. De Sydney gaf het signaal dat de bemanning zich over moest geven, maar toen er geen antwoord kwam, werden er nog enkele salvo’s op de Emden gevuurd. Pas daarna besloot Von Muller de vlag te strijken. Tegen die tijd sloegen er op de Emden midscheeps al enorme vlammen uit. In een poging om zo veel mogelijk bemanningsleden te redden, stuurde de kapitein het schip richting het rif voor de zuidkust van North Keeling.


North Keeling ligt ongeveer op 27 km van de hoofdeilanden van de Cocos-Keeling groep en omdat het behoorlijk afgelegen ligt, gaan er niet veel mensen heen. Het was dan ook heel bijzonder om op die plek te duiken en de resten van het schip te zien liggen. Ondanks dat het schip al deels is geborgen, is er nog een hoop achtergebleven – zoals je kunt zien op de foto’s die we hebben gemaakt. Een van onze teamleden is zelfs samen met Triss van Parks Australia het eiland op geweest om de resten van het schip op het land te documenteren! Net als bij de Phaeton hopen we een mooi 3D-fotogrammetriemodel van het schip te kunnen maken om een goed overzicht van de locatie te krijgen. We hebben vastgelegd wat er nog over is van het schip en ook een corrosiemeting uitgevoerd.

In de komende dagen gaan we verder met het zoeken naar de Fortuyn en de Aagtekerke. We zullen jullie zo goed mogelijk op de hoogte houden met de beperkte internetverbinding die we hier hebben…

 

Physical work-out and food for thought

During the two months that we have been here, we have been training for the diving course. This is because the diving course requires us to pass a physical fitness test with the following tasks:

  • 1000m surface swim without fins in under 30 minutes
  • 2.5 km run in under 15 minutes
  • 25 m underwater swim without fins (fully submerged)
  • 1 minute breath holding in swimming pool at 2 m depth

Most of these tasks are not that hard, but we had to practice for the 25 meter underwater swim and the 1 minute breath holding. The reason for the fitness test is that professional (scientific) diving requires a high degree of physical and psychological fitness. That is also the reason that we have to pass a diving medical examination. This medical examination consists of a lung x-ray, blood test and a cardio test. The training paid off and we passed the fitness test last week. The medical examination will be in the first week of November.

The track where we did the 2,5 kilometer run test.
The track where we did the 2,5 kilometer run test.

The diving course consists of a theoretical and a practical part. During the course we will also get diving first aid lessons. The price for the course is DKK 13,500 (or +/- 1800 euro). This fee covers all the course material, the diving logbook, diving first aid manual, transport, etc. Alternatively a course fee of DKK 20,400 (or +/- 2750 euro) includes a personalized made to measure (MTM) membrane drysuit and a diving hood. It is also possible to buy an undersuit through school for a reduced price. We bought the drysuit and the undersuit, because we did not have either yet.

The diving course starts at November the 17th. We could actually choose to do the diving course in November or in May. This is because the diving course works best with 8 people at a time and so the class needs to be split up. We chose November, because when we have our diving license there will be opportunities throughout the year to work on different projects. One of these projects is for instance the one in Ribe, that we talked about in the previous blog. We hope to get a lot of diving experience this year!

Apart from the diving course we have off course been following classes at the university. This semester we have 3 classes:

Archaeology and Management

This course focuses on archaeological (underwater) heritage management. The purpose of this course is to give us practical and theoretical tools concerned with the identification, protection, management and preservation of the material remains of human activity in the past (of whatever period and in whichever region of the world) and with the interaction that this involves with all kinds of stakeholders. What we have done during this course for instance is to discuss the differences in laws and legislations in the different countries that we are from. This is to establish an international overview of the conditions for the maritime archaeological work.

Man and Sea

This course gives thorough knowledge of the complex history of human activity by and on the sea. We get a chronological and thematic overview of central aspects of the maritime history of mankind from the Stone Age until now. The course focuses on how mutually related spheres such as fishing, transport, trade and technology have formed human society along and across the seas in constant interaction with the natural environment.

Introduction to Methods in Maritime Archaeology

As you might be able to tell, the other courses are more theoretical courses with a lot of reading and discussions. The methods course is a more practical one, it focuses on the methods and techniques used in maritime archaeological field work. During this course we get a thorough knowledge of the tools that are available to a maritime archaeologist. Significantly, we will have a research-based insight into the key questions to be asked in connection with a maritime archaeological survey in different phases. To pass this course we have to do a group assignment in  which we have to make a 3d-model of a small boat. The small boats are situated in the local fishery museum (Fiskeri- og Søfartsmuseet, Esbjerg). Different methods can be used to record the boat, like drawing, photogrammetry or measuring with the Total Station. A combination of these methods can off course also be used.

Work in progress on the computer vision photogrammetry model for one of the small boats
Work in progress on the computer vision photogrammetry model for one of the small boats

Last Friday we went out to the ‘Konserveringscenter Vest’ in Olgod. Our professor for archaeological methods, Jens Auer, was asked to look at and record a stempost of a ship that was found in a fishing net. A stempost is the main foremost (vertical) timber of a wooden boat that is fastened to the end of the keel. It forms the main part of the bow and extends to the deck or even above deck. The stempost is almost 6 meters long and probably has an English origin. When we got there, we first got an interesting tour through the conservation center.

The tour through the conservation center
The tour through the conservation center

Afterwards we recorded the stempost. We made photos and videos in order to make a photogrammetry model of the stempost. We also made sketches and recorded the stempost using a Total Station. During the maritime programme there will be a lot of these practical exercises, which are really nice because they give us hands-on experience!

We are really looking forward to the diving course! When it starts in November we will keep you updated on our progress in this blog.

Goddag!

Robert de Hoop

Nicole Schoute

Vietnam Maritime Archaeology Project – The final results

With the project coming to a close, results have to be written up. The versatility of the different assignments means that there are a number of conclusions that can be drawn for this project. These results range from the archaeological results of the underwater archaeology conducted to the more anthropological results of the Vietnamese shipbuilding research.

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The visits to the different shipbuilding yards near Hoi-An helped in giving us an understanding of the maritime techniques used in Vietnam. This resulted in numerous drawings of ships as well as in giving the trainees extensive practice in the process of drawing these ships. These results are important for both the capacity building as well as to create a frame of reference for possible finds, and how to register these finds.

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Furthemore, extensive practice and research with 3D-photogrammetry software was carried out. This way we were able to create 3D records of a number of boats, ceramic artefacts, and cannons located in Hoi-An and Hue.  These were usually objects of unknown origins and these 3D models can be used by experts to gain more information regarding these artefacts. Attempts are also being made at creating a 3D model of the site at Bai Ong which could be extremely useful for mapping and possibly even locating finds in the area. This modelling is still in progress.

As for the underwater archaeological surveys, a number of different results were achieved. First of all, we (re)located a number of potential archaeological sites, such as the stone anchor site, through diving surveys and interviews with local fishermen and divers. Also, numerous sites containing ceramic artefacts were located around the coastline of the Cu Lao Cham islands which can be useful for future research by the Vietnamese Institute of Archaeology.

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Most importantly though was the discovery of the possible shipwreck site located in Bai Ong. This site contained a plethora of ceramic artefacts and could prove to be an important site for future research.  What we were able to find out about the site in a three day non-intrusive survey was this: the site consists of an area with broken pottery. Most of them are from one type of storage jars from the 16th to 17th century. The objects are caught in sand pockets and beneath rocks in the shallows of the shore of the Cham Islands. Other pottery found at the site– in smaller amounts – also has the same date.  The pottery that is surfacing the seabed is concentrated in a small area of about 20 by 25 metres. A corroded iron nail that was found on site might indicate the presence of a shipwreck. Hopefully wood is still preserved in the larger depressions between the rocks that are filled with sand. Further research has to confirm this. There were reports of wood being sighted at the site but we were unable to relocate this.

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I hope everyone has enjoyed following the project through this blog and other sources, and keep following the maritime programme for more updates on the numerous projects that they have going on!

For the last time, greetings from Hoi-An,

Mike.

Vietnam Maritime Archaeology Project – Australian 3DMAPPR special

Today’s guest blog, written by Australian participant and trainer Ian McCan, is related to the use of 3D photogrammetry software and techniques. These techniques create a 3D image of an object by combining a number of photographs through a software programme (see also the blogs of the RCE dive team on the Oostvoornse meer: http://wp.me/p4KclF-4v) . This 3D object can then be rotated and send to people around the world as a means for research, for promotion purposes, or as a way to get the public involved. Ian McCan will now tell you more about the 3D photogrammetry project that he is involved with.

The 3DMAPPR (3D Maritime Archaeology Project – Perth Region) dates back to April 2014 and is a community-based project partly funded by an Austral-Asian Institute for Maritime Archaeology (AIMA) Scholarship in order to financially support the first stage of  the program of shipwrecks site documentation, visualization and management. The main focuses of this starting step are:

(1) the development of a low-cost photogrammetry package intended to facilitate the (3D) recording of underwater cultural heritage in the Perth region

(2) the training of community members in underwater photogrammetric recording and image processing techniques.

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A 3D photogrammetry example made by one of the VMAP teams, showing the programs ease of use

The longer-term objectives for this project are for the hardware/software package and 3D imagery results to be used as a solution for low-budget (archaeology)groups or volunteer organizations as a management tool for the continual monitoring of endangered and important archaeological and non-archaeological sites.

This would also provide the ground work for the future use of augmented reality technologies as part of new virtual shipwreck trail visualization and for the use of 3D printing technologies within museum displays. This project is therefore not only focused on its application in archaeology as it is conducted today, but also aims to help create the future of archaeology.

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Despite a comprehensive knowledge of maritime sites in the Perth Metropolitan area, the current status and condition of many sites remains somewhat uncertain due to a lack of up to date management and monitoring. This is associated with several additional factors, including a scarcity of detailed documentation for many local sites; a lack of any facility or tool to monitor the causes, nature, and scale of changes to local sites and their immediate environments; and a reliance on the involvement of (often) amateurs and hobbyists, with accompanying pressure on time, money, and expertise. Given these issues and the considerable constraints and limitations inherent in traditional (manual) survey and recording techniques, there was a clear need for alternative approaches to be adopted and implemented if on-going management of the sites in the Perth area and beyond is to be both timely and effective. Necessarily, any such approach needs to meet several criteria in order to make it fit for purpose. This includes time and cost effectiveness; ability to utilize off-the-shelf hardware and software systems; capability of operating with minimal user intervention; and accuracy and repeatability.

The technical details

A detailed literature review and preliminary land-based and underwater testing indicates that multi-image 3D photogrammetry best meets the above requirements. Multi-image 3D photogrammetry (MIP) is a term that describes the use of large 2D image datasets to reconstruct the 3D geometry of an object or scene using Structure from Motion (SFM) and Dense Multi-View 3D Reconstruction (DMVR) techniques. While the use of photogrammetric techniques has a long history in the context of land-based natural and cultural heritage documentation, its wider adoption and adaptation to underwater conditions has been considerably delayed owing to a number of technical and practical constraints and high technical overheads.

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While several of these issues – particularly those related to underwater conditions (e.g. water turbidity, poor visibility, light attenuation and refraction) – remain, the advances in low-cost computing, digital imaging and software design have facilitated the development of what are effectively multi-image photogrammetry solutions. These solutions offer considerable advantages over traditional techniques, including rapidity, objectivity and relative simplicity of implementation; suitability for capture of large and complex objects; high potential accuracy; ability to use inexpensive and highly portable equipment (such as GoPro cameras); captured images contain all data required to facilitate 3D reconstruction; and the ability to utilize legacy data, thereby facilitating reconstruction and comparison of data from successive surveys and/or archive sources.

There are a considerable number of open-source (the Bundler + PMVS2 + CMVS assembly), web-based (123D Catch, Hyper3D/Cubify3D) and stand-alone (Photoscan, Photomodeller Scanner) multi-image photogrammetry solutions available at the moment. Each of these solutions offers varying degrees of user input and control over the resulting dataset. However, for the purposes of the project, it has been decided to employ Photoscan Pro, due to it being somewhat of a de facto standard in the field of archaeological photogrammetric documentation, being employed in a number of terrestrial and (increasingly) underwater scenarios. Unlike competing packages, Photoscan Pro represents a unified solution that incorporates not only the standard image acquisition, image rectification/alignment, and geometry extraction processing pipeline, but also has geo-registration capabilities and the option to output digital elevation models (DEM) and orthophotography (Geometrically corrected aerial photographs). These functions make it a versatile package suited for the many different archaeological needs.

Ian McCan