Interesting and useful new tool

Centre for Image Analysis at Uppsala university has developed a very interesting tool that could be used for historical datasets. It is used to piece fragments of an object together and reconstruct the object. The obvius use could be for pottery or human bones, espacially sculls. The input to the system is 3d-scans of the different pieces. The software analysis the pieces and makes an rough alignment. Then with the help of a haptic device the researcher can put the pieces together and try to make them fit exactly.
This would be useful when working with very fragile objects that shouldn't be touched too much. Just 3d-scan them and then put the scans in this system and once it is there, they can be handled without risking any damage to the objects.
The Humanities lab sent them three pieces of a clay plate to test the system. Here is a video showing how the system is used.

http://www.youtube.com/watch?v=m1EcVWRiPT0

We will soon send them 15 pieces of a scull that will be very interesting to see if the system can handle as well.

/Stefan

Visualizations for an exhibition

The Humanities lab are involved in a really interesting project at the moment. We work together with the Historical museum in Stockholm in preparing an exhibition that will start next year. Part of it is about the battle of Visby in 1361. Visby is the largest city of Gotland, which is a big island to the east of Sweden. In 1361 it was invaded by the Danish army and in the middle of the summer there was a terrible battle just outside of Visby. The local army, consisting mainly of peasants, boys and older men, was no match for the professional and experienced Danish army and it is estimated that 50% of the male population at Gotland at the time was killed in the battle.

A skull with 11 damages from three different weapons

The exhibition will tell an exciting, but also horrible and nasty story about how people was sacrificed, died, and was buried in several mass graves outside the city wall. The skeletal remains in the graves bear witness of terrible wounds. What happened on the battlefield? How was it to be in the heat of battle, cornered between the high wall and the Danish army? The Historical museum would like to envisage some of this and we are helping out with part of the visualizations. 

A chopped off foot

First we are 3d-scanning some of the skeletal remains with clear traces of different weapons. It is three skulls, one arm, one leg and a chopped off foot. We are using a NextEngine scanner to do this job. Just to make sure, we have taken a lot of pictures as well, that could be used in PhotoScan.

The museum has hired an expert in medieval weaponry and weapon techniques and he has analyzed the wounds very carefully. Based on this analysis he could reenact the most probable movements with the most probable weapons used to inflict the different wounds. We, of course, put him in our motion capture system to record these movements so we can use them as a base for the animations that will be done to visualize what happened. 

The long axe is prepared with mocap markers

 /Stefan

4DGIS-ongoing experiments

During these days I am playing a bit with the data from Catalhoyök and Uppåkra, in both cases I am experimenting  with Image Based Modeling techniques and Arcscene 10, with the goal to have a clear idea on what the limits and potentialities.
After a long discussion with Camilla Mazzucato from Oxford University we started implementing more models and we are planning -together with a larger group of researchers- to start working on the design of a new typology of database.
So far we grouped the models in multi patch files, but I am not jet sure if this will be the best or the only solution for this project, in fact it depends a lot from the typology of visualization that we want to reach.

3D models realized during the excavation season 2012 in Catalhöyuk

Next spring's main goal,  it will be  the import of  the entire dataset of models realized during the last excavation season,  with the goal of start working  on new workflows to combine into ArcGis data of different typology (vector+3D models etc). In particular I would like for the next excavation season to explore the possibility to have a 3D distribution of findings (as points) visualized on the 3D models, let's see how far we will go..


/n

3D-scanning in the jungle

Cave entrance seen from first chamber

At the end of May I went to Belize to work at a Maya site out in the jungle for three weeks. The site, originally referred as “Awe Caves”, is a medium-sized Maya ceremonial center located in the western part of Belize. It is of particular interest because a large cave with an extensive dark zone tunnel system resides directly beneath the largest temple in the site core. The project of 3D documentation and reconstruction of this site is part of a larger research project of preliminary investigation started in the summer 2011 and directed by Holley Moyes, UC Merced. The first year some 3D documentation of the excavations was done by Fabrizio Galeazzi, UC Merced. This year one of the ambitions was to 3D-scan the complete cave. The cave is a natural geological structure, but has been divided into nine chambers in succession, by the Mayan people. The cave turns around so that the last chamber enters into the first, about 10-15 meters up on one of the walls in the entrance chamber. The different division of the chambers varies from clearly manmade structures to more or less natural boundaries.

Snapshot from pointscloud. The colored area shows a manmade wall

The 3d scanning was done with a Faro Focus 3D scanner. It is a small and compact scanner, that is easy to carry and has everything needed to scan built in. Faro Focus 3D including tripod, weighs about 8 kg and is therefore the ideal scanner for a mission of this kind. One important benefit from the small format of the scanner is evident in the fact that the scanning of the complete cave were made in just eight days.

Scanning of excavtion in the cave was done with light

Right from the beginning it was decided not to try to capture color information in the cave, but only settle for the geometry. To capture color information would demand large amounts of lights to illuminate the cave properly. Bringing enough lights and spending time placing them as good as possible would have been a huge and costly task far beyond the scope of the project.

At the start of the campaign, a fairly normal scanning strategy for larger structures was applied. This was a relatively efficient approach in the entrance chamber, but further into the cave it got more and more difficult. With such an extremely irregular geometric structure found in the cave, the risk to miss important parts was much larger than usual. So after a few days the scanning strategy significantly changed and scanning positions were moved closer together to be sure to cover as much as possible. It culminated in the fifth chamber, which was a complete jumble of rocks, stalactites, stalagmites, narrow cavities and hidden structures. This complex geometry led to a scanning strategy, in which the different scan positions were placed only a few meters from each other. This of course gave us a huge amount of scans that, at this writing, still isn’t fully post processed. 

The humidity caused other problems as well

Another objective of the scanning campaign was to verify how well the scanner handled the very special climate prevailing in a place like this. This is subtropical jungle and the work were made during a time of year when it was quite a lot of rain, high humidity and relatively warm. Inside the cave the temperature was slightly lower, but the humidity was significant. Anyone who has worked with electrical equipment in these conditions can tell you that humidity plays tricks with equipment that does not occur in dryer environments. 

Scanning part of the entrance from a spot in the jungle

We were pleased to see that the scanner handled these conditions well for most of the time. The battery ran out faster than usual, but that was expected. The only problem experienced was that the touch panel of the scanner stopped working on a number of occasions. The touch panel is mainly used to adjust the settings for the different scans, such as resolution or whether the scan should be done with color or not. Once these settings are made, the need to use the touch panel is not that big, with the very important exception of starting each new scan. Hence a non-functioning touch screen could be a serious problem. Fortunately, the scanner also provides a more stable button under the touch screen, which can be used just to start scans if you cannot start them otherwise. That saved a lot of time, since the only way to get the touchscreen to work again was to turn the scanner off and let it rest for a couple of hours. To prevent problems with humidity, the scanner bag was equipped with several small bags of silica gel during the entire period in Belize. It is used as a desiccant to control local humidity and may have done some good in keeping the scanner in such a good shape.

All in all it was a very interesting trip and we are really looking forward to have time to work with the data.

Scan of the entrancecave. To the left of the middle you can see two people that happened to be scanned. Good to use as a reference

/Stefan

CENCELLE

I just come back from a very short archaeological mission in Cencelle (figure 1), where  together with  Stefan Lindgren and Doriana De Padova we joined the excavation team leaded by the Prof. Francesca Romana Stasolla, and her collaborators: Dr. Sergio Del Ferro, Dr. Lorenzo De Lellis and Dr. Lara Tonizzo Feligioni. 

Figure 1 Archaeological excavation of Cencelle, Tarquinia

Cencelle is a middle age town founded by Leone IV during the IX century with the aim to provide a safe refugee to the inhabitants of Centumcelle (Civitavecchia). 

Centumcelle  was an ancient  town  along the costs few miles north of Rome, which in that period was constantly under the attack of the Saracens.  Cencelle is  amazing, the landscape is beautiful and the site incredibly rich. 

The excavation is under the scientific direction of the University of Rome "La Sapienza", that together with l'École française di Roma, started the excavation in the 1994.  Goals during our short permanence there were: the documentation of structures no more under archaeological investigations using the laser scanner, the use of Image based modeling techniques for the documentation of the ongoing excavation (cemetery), the use of the GPS to map the site.

Our work was mainly focused on finding a work methodology  that could have been  easily integrated with the current system of documentation in use in Cencelle.

As previously explained, we decided to employ the Laser only for the structures that were no more under investigation, in fact, despite the efficiency of the scanner in providing resolute, accurate and precise 3D models, the time  required for the  data post processing would have been not sustainable.

Figure 2 Map site realized using the RTK GPS

Despite some problem with the vegetation... in two days we handled to finish the work with the scanner acquiring material that will be used in the coming months  by Doriana De Padova to highlight aspects of these structures not jet studied before.  At the same time, with the help of the students we started the documentation campaign of the ongoing excavation of the cemetery in order to provide material that (we hope) will help the excavation team to have a better view of the complicated relations between the different graves currently under investigation.

Detail of the cemetery, 3D model of one of the burials processed in Photoscan and visualized inMeshLab

Once again the use of this technique have been incredibly efficient, already the first day it was possible to produce dense and detailed models able to provide an extraordinary view of the spacial relations between the different features of the area under investigation.
Differently from a normal  raster images or vector file, the use of 3D models provide an impressive view of the ongoing situation that can provide different perspectives, already  during the excavation campaign or even after the end of the investigation. The GPS has been used to produce a quick description of the topography of the site, moreover this instrument allowed to calculate the position of Control points that will be used to geo-reference the 3d models coming from the different technologies employed during this archaeological campaign.

3D model of the cemetery processed using  Photoscan and visualized in MeshLab

3D model of the cemetery processed using Photoscan and visualized in MeshLab

3D model of the cemetery processed using  Photoscan and visualized in MeshLab

/n

Pompeii acquisition campaign second part

     

   Figure.1 Map of the insula, in green
Casa di Cecilio Giocondo

I just come back from an intense week of scanning in Pompeii, where together with Stefan Lindgren (LU), Carolina Larsson (LU), Matteo Dellepiane (CNR) and Marco Callieri (CNR) we finished the 3D acquisition of the insula V1.
Last year we focused on the houses of "Cecilio Giocondo" and "Torello di bronzo" (both part of the insula) and at the end of the campaign, we  found the time and the energies to acquired a large portion of the street that surround the insula. This year, even if the weather slowed down our work, we completed the acquisition of all the environments left from the previous campaign, closing in only two days the documentation of the insula (fig.1).

Figure 2 one of the rooms of Casa degli epigrammi greci,    

The knowledge gained last year allowed to  speed up consistently the acquisition campaign; in two days, with two teams, we collected and almost  aligned approximately 200 scans. Pompeii is really an incredible site, every small room has so many different typologies of information, even if the environments are almost empty the walls are characterized by a large  amount of details to document (fig.2).

During this season we mainly focused on the north-west and south-west part of the insula, acquiring environments such as: Casa deli epigrammi greci, the bakery,  Caupona, etc.

These areas are characterized by small and very tall rooms, all connected each others by narrow corridors and small entrances, moreover a number of containers for storage or ovens were still in their original position -bakery or the shops- and the use of the scanner for the acquisition of these rooms was not sufficient (fig.3).  In specific the containers for the storage were so close each other to do not allow any (safe) scan position. In this specific case we decide instead to acquire these elements using image based modeling techniques. This approach proved to be very successful and easy to integrate with the laser scanner data. 

Figure 3 Alignment process of the Casa degli epigrammi greci

The use of just one instrument or one technique would have never been enough to gain our goal  (fig.4). From my experience out in the field, I learned that does not exist any technique, technology or documentation platform able to cover entirelly the documentation of an archaeological site. Integration of technologies is the only proper way to face archaeological sites. Flexibility of methods is the only characteristic that allow archaeologist to develop a creative and dynamic research using technology.
I found this campaign very challenging, the environments were not easy to document, and the constant passage of tourists did not help...

Last year we worked hard to find a good workflow to post process the data and I think that this year, with some help from our students from Digital Archaeology Course we should be ready with a complete model. 

Figure 4: The Faro Focus 3D scanner inside

the oven before the scanning, 

in the picture: me, Matteo Dellepiane, and Mr. P

At the end of the project, we are also planning to connect high resolute 3D models of every room with the documentation available on the website of the Swedish Pompeii Project, in order to make accessible this work for everybody.

At the end of the campaign we decided to scan our team and leave a virtual footprint of us in the insula ;-)

/n

Insula V,1 entrance of Casa del torello di bronzo

Scanning Team in 3D, from left: Matteo Dellepiane, Marco Callieri, Carolina Larsson, Stefan Lindgren,
Nicolo' Dell'Unto

Çatalhöyük 2012 and 4D GIS

I came back few weeks ago  from the archaeological excavation of Çatalhöyük, Turkey
where this year I tried  new experiments in the use of 3D technology to document and visualize ongoing archaeological excavations.
Last year I did tests on site using  Image Based Modeling techniques to document the investigation of the building 89, in that occasion the team of the university of California Merced directed by Maurizio Forte, were running similar experiments using instead a phase shift laser scanner, they got interesting results  and the use of both these techniques in the same excavation context gave us a very good feedback on how different technologies that produce similar results (resolute 3D model) obey to different work-flow of data capturing and post processing.

After this tests we gain a good knowledge on how making these tools compatible with ongoing excavations and how to manage the data in a reasonable time frame.
At the end of the first season (2011) It was possible to visualize in the same platform (MeshLab) the temporal sequence of most of the units found during the investigation, moreover  thanks to a total station grid provided by the survey team who operated during  that season, it was even possible to geo-reference all the models realized during the campaign.

The first year was very successful, especially  for what concern the creation of a functional work flow to use during the investigation process, but very few questions about archaeological methods came out. This happened probably because we could not visualized our models in the same  platform where all the other data were stored: the GIS system of the excavation.

After the first season of experiments we figured it out that  Image Based Modeling techniques represent today the best solution to generate 3D models of the ongoing investigation, in fact the accuracy and precision of this methods has been proved to be  more than enough  for any archaeological documentation, moreover using powerful laptops it has been possible to produce in few hours (sometime even in 45 minutes) complete 3D models of the buildings.

3D model of the Building 77 realized using Photoscan AgiSoft

Here some reference about  tests that we did in collaboration with Matteo Dellepiane and Marco Callieri from the Visual Computing Lab, CNR, ISTI, Pisa  about the use of image based modeling techniques to document archaeological excavations : Archaeological excavation monitoring using dense stereo matching techniques 


This year together with UCM we decided to mainly use this method (image modeling techniques) for the documentation of the ongoing excavation,  laser scanner technology instead was mainly employed for the documentation of the entire site with point's clouds.
From the very beginning  we decided to use Image  based modeling techniques on a larger scale, ...I was so much curious to understand if this method was efficent also in a such huge scale, after the first season this was obviously possible, but you know... theorizing something is not exactly the same of doing something... ;-)
 
The results were really interesting! In fact it has been possible to work on several buildings at the same time and geo-reference all of them in the same space, moreover with the help of Camilla Mazzucato,  researcher at the university of Oxford, we handle to transform the 3D models in features and finally visualize our work  into the GIS system of the excavation (Arcscene) connecting each other data coming from different seasons and different teams.
Together with James Taylor from the university of York, we started discussing how this will effect the field activities and we started brainstorming new workflows in order to integrate this approach into the documentation system in use in Catal.
At the same time an interesting  discussion started also with Scott Haddow from the osteology group that experimented  new ways to use this technique in osteology, here some reference from his blog.

 group of 3D buildings visualized in Arcscene

Before the beginning of the campaign I had the chance to discuss with Åsa Berggren and Björn Nilsson about several possible scenarios,  I think that  these results represent the best  starting point we could get to begin a new exciting research work.

The results of this experiment  open to new questions such as: how the use of this new tool will influence our way to perceive and interpret the data? How our work will effect the investigation of other archaeologists in the future? And... who will answer these question?

In order to have a deep understanding of the problem. I think it is fundamental to bring this work more and more into the field, Çatalhöyük is not just a FANTASTIC archaeological site, but a real experimental environment, where new ideas and discussions comes out constantly


/Nicolo' Dell'Unto