Mandrone WW1 Project

On August 25th and 26th 2016 a team of divers and archaeologists has explored the bottom of lake Mandrone (2.409 m.a.s.l.), Adamello Alps/Italy. Under the direction of prof. Tiziano Camagna, the team has localized and documented the wrack of a boat build there during World War I.

Team-leader Tiziano Camagna was supported by the archaeologists of Arc-Team Ltd. (Cles/Sexten – Italy), Alessandro Bezzi, Luca Bezzi and Rupert Gietl. Massimiliano Canossa and Nicola Bonisegna, underwater-experts from NauticaMare DiveTeam, have realized high-resolution videos and photos.

The main target of the mission was the localization and documentation of the wooden remain on the ground of lake Mandrone. The boat was build between 1916 and 1918 and sank some years after the end of WW1. Pictures and videos taken by the divers will now be processed by the archaeologists in order to extract a detailed 3D model using Computer Vision technologies like SfM (Structure from Motion) and MVS ( Multiple View Stereovision).

Tiziano Camagna first localized the remain in 2003, comparing it with two historical photos published by Luca Viazzi in the volume "I diavoli dell'Adamello - 1915 -1918 La guerra a quota tremila". The first shot is showing Italian mountain troops (Alpini) building a boat near the “Julius Payer” refuge, situated about 800m northeast from lake Mandrone. The second Capt. Castelli rowing on the lake.

The Adamello Alps have been one of the highest war theaters of WW1. In the area around lake Mandrone and the refuge “Città di Trento” we can still find lots of archaeological remains of that period: Trenches, barracks, observation positions and a small military cemetery.

Austro-Hungarian and Italian troops had not only to fight against each other, but primarily against the harsh climate on altitudes up to 3.900 m.a.s.l., 10-12 meters of snow in the winter and temperatures right down to -30°C (-10°F).

Thanks to the support of the wildlife park “Adamello-Brenta” and the Gallazzinis, tenants of the refuge “Città di Trento”, the equipment of our expedition was transported on site with the goods cable lift of the refuge. The team went up by foot, walking about three hours starting at the head of “Genova” valley. On the last stage, from the refuge to the lake, the gear was carried on the back.

In order to facilitate the transport, divers choose light equipment like the sidemount system.

During the dive our photographer Nicola Boninsegna localized a wooden trunk on the ground, a discovery that gives rise to some new research questions, considering the total absence of trees on that altitudes. 

The find will be analyzed soon, in order to get dating and identification of the species.

This mission was also an opportunity for a high altitude test of our ROV prototype (Remotely Operated Vehicle), named ArcheoROV developed by WitLab laboratories from Rovereto, in collaboration with Arc-Team.

Last but not least the team wants to thank the Department for Cultural Heritage of Trento (Office of Archaeological Heritage) for close cooperation.

3D documentation of small archaeological finds

Today I want to present the results of an experiment we did 2011 thanks to the collaboration of Nicolò Dell'unto (Lund University).

The goal of the project was the comparison between different methodologies in documenting small archaeological finds. In such a wide applications field we decided to evaluate mainly two technologies: Computer Vision (Structure form Motion and Image-based modeling) and optical sensors.

In both groups we compared open source and closed source possibilities, documenting the same artefact with Microsoft Photosynth (closed source software), Python Photogrammetry Toolbox (open source software), then with a NextEngine Scanner (closed source hardware) and finally with Three Phase Scan (open source hardware).

For the test we used a souvenir from Lund: the small statuette of a female viking (we called her Viky) you can see in the image below.

The test object: Viky

  

The characteristics of such an object granted us a medium-high gradient of difficulty (a good level to test our technologies).

For all the post-processing elaboration we used MeshLab (also when another commercial software was avalaible, like for the NextEngine Scanner), because we considered it a "killer application" for mesh-editing (by the way, for next experiments I would also consider CloudCompare, another great open source project). The screensot below shows the four results of our experiment.

 

Comparison of the four 3D documentations

To better observe the differencies between the four 3D models it is possible to check the next panoramic 2D (sorry I did not clean all the models, but I think it is enought to understand the general quality):

Python Photogrammetry Toolbox

MS Photosynth

Three Phase Scan

NextEnigine Scanner

As you can see there is not a big difference between the two Computer Vision documentations, as they are based on similar software (having a common origin in the Photo Tourism project), while the comparison between the NextEngine and Three Phase Scan is simpler: untill now the open source instrument is not accurate enought to record small objects (it is possible to observe the error on the arms of Viky), having too low quality for archaeological aims. Anyway, it has to be said that the cathegory of the two optical sensors is different: the NextEngine is a triangulation scanner (very accurate and precise), while the Three Phase Scan is a structured-light scan. Unfortunatley we had no time to consider also the open source MakerScanner, which would belong to the same cathegory of the NextEngine.
In conclusion our opinion about 3D small finds recording is that actually the NextEngine is a very good low-cost solution (sadly not open source, IMHO) and it is an optimal choice in those pojects where there is the necessity to document a big amount of objects in a short time. If we consider also the price, then the better applications seems to be the Computer Vision based software Photosynth and Python Photogrammetry Toolbox (PPT). Personally I prefer the second one for two reasons: it is a FLOSS (GPL licensed) and has no need of internet (while with Photosynth it is necessary to upload the pictures on external servers). This characteristic makes PPT a perfect tool in difficult situations, like, for exemple, an arcaheological mission abroad. In these conditions it is possible to record 3D models with a very simple hardware equipment (just a digital camera and a laptop), in short time (at least during data acquisition) and without an internet connection (as I described in this post). Moreover PPT (and in general CV vision applications) gave us also good results in "extreme" projects, like we illustrated in the slides (sorry, just italian) of our contribution during the Low-Cost 3D workshop, held in Trento in March 2012


2016-04-07 Update

In 2011 we wrote an article about this experienced:

ResearchGate: Article
Academia: Article

I hope it will be useful, even if no more up to date it.

3D for archaeological finds

One of the most common question we receive about SfM and Computer Vision techniques is: "is it possible to document in 3D also small objects like archaeological finds?". The answer is yes, it is, and there are two possible ways:

1. putting the object to record on a turntable (with a black panel as background) and taking pictures from a fix point  (as I described in this post)
2. taking pictures walking around the object (the easiest way)

Untill now, in both cases, it is better to use Bundler 3 instead Bundler 4 (that seems to have some problems with symmetrical objects). Anyway for option 2 there is no need to "erase the background" so it is possible to use also the newest version of the sofware (which is the one inside Python Photogrammetry Toolbox). This is because other objects in the background can help Bundler to find the right position of the cameras for every picture. the image below is an example of this situation: I took the photos walking around the archaeological find, which was simply placed on a piece of wood (over a normal A4 paper, for metric references).  

3D documentation of arcaheological finds with Bundler and PMVS2

The archaeological find in the picture comes from the mission in Khovle Gora (Georgia) of University of Innsbruck, Department of Ancient History and Near Eastern Studies, (Walter Kuntner and Sandra Heinsch) and Javakhishvili Tbilisi State University (Prof. Vakhtang Licheli).