ATOR (Arc-Team Open Research).
The blog spreads tests, problems and results of Arc-Team research in archaeology, following the guidelines of the OpArc (Open Archaeology) project.
it has been a long time without post here in ATOR, but this year we had to work on several different projects, without the possibility to report fast feedback in our blog.
I start today to write again, due to the fact that some of these projects grab the attention of different institutions of the academic world and, in particular, this happened for our underwater archaeology missions.
Of course our primary interest during our diving is related with the archaeological perspective, but often the data we collect can be useful for other specialists (e.g. limnologists or biologists).
This is the reason why we decided to share our data and we start today with the bathymetric chart of Lake Tovel (previous post in ATRO: 1, 2). I processed this map working on the Red Lake Project, a research, directed by Prof. +Tiziano Camagna, which tries to study the medieval submerged forest of Lake Tovel (Trentino - Italy). I produces a 3D model of the bathymetric chart of this lake directly digitizing the map of Edgardo Baldi did in the '30s. Than I calibrated the result with the LIDAR model of the landscape, freely accessible form the geographic open data portal of the Autonomous Province of Trento (here a short tutorial about how to download data from the webgis).
Here is possible to download the file (an ESRI ASCII grid), ready to be integrated in most of the GIS software (below a screenshot of the data in GRASS GIS).
Tovel Lake bathymetrci chart in GRASS GIS
The data are available under the following license:
As many of you know, since some years we (Arc-Team) are supporting Prof. Tiziano Camgna's project regarding the underwater forest of Lake Tovel (1, 2) in Trentino (Italy).
In the past days we are asked to give a lesson about our contribution to the project at the Liceo Scientifico Bertrand Russel of Cles (TN, Italy). In order to prepare some data for the event, I started to work on a 3D map of the underwater surface of the lake and, to collect material for different ArcheOS videotutorials I recorded almost the complete process. For this reason I start today a series of "minipost" to publish this material, hoping that this will be useful for some readers.
In this first minipost I will write about open geodata, which are very important for archaeologists, but also for other professionals. Before to enter the topic, I have to say that we live and work (fortunately for us) in a Italian province (Trentino) which is sensible to this matter (open data). If you can understand Italian, you should read +Maurizio Napolitano's blog, one of the real expert in this field currently working at the Fondazione Bruno Kessler.
During the Project Tovel I needed geographical open data to set up the GIS system with some basic cartography. More specifically I started with the "Carta Tecnica Provinciale" (a technical map of the province), which I downloaded form the "Portale Cartografico Trentino" of the S.I.A.T. (Sistema Informativo Ambientale e Territoriale of the Province Trentino). As you can read in the portal (sorry, just Italian), the C.T.P. (Carta Tecnica Provinciale) is available Under the Creative Commons Attribution 2.5 terms.
The videotutorial you can see below just show the simple process to access and download these data (in raster or vector) form the webgis service.
I hope this first post was youseful for some of you, have a nice day!
It is long that Alessandro and me wanted to write this post, but for one reason or another, we could not work on it.
Today I decided to do it in order to answer two questions that people often asked us during conference or lessons:
1) Is it possible to work with SfM/IBM techniques underwater?
2) Is it possible to extract 3D from a movie?
As regards the first question, I can report that since we (Arc-Team) started to work with SfM and IBM (2009), we did also tests underwater and they gave us positive results. This is one of the main reason why we invested so much time on the researchin this filed: SfM and IBM methodology, until now, is one of the best solution in archeology, due to its versatility (it can be used for underwater or aerial documentation, in low light conditions or in precarious situation, during mission abroad, etc...). We already underlined this concept when, with the help of Nicolò Dell'unto (Lund University), we compared different methodology to record 3D documentation of archaeological artifacts. The result of this experiment was presented during the ArcheoFOSS 2012, in Napoli (see the related slides and this post). During the workshop "Low cost 3D: sensori, algoritmi e applicazioni", we had the opportunity to better analyze the use of SfM/IBM in extreme working conditions, strengthening our point of view about this methodology (see the related slides). The image below is an example of an aerial 3D documentation done with an open source UAV and Python Photogrammetry ToolboX...
Aerial documentation with a KKopter and ArcheOS (PPT)
... while this other image shows the results we achieved using some pictures that Victor Jansa, of TUWA ("Tauchverein für Unterwasserarchäologie"), sent us to do a test.
Test with Victor Jansa's pictures (done with PPT)
In order to answer the second question, I can say that, facing our experience, it is possible to reconstruct 3D models from videos (and I guess this is one of the aims of SfM itself). We did some tests about this topic, getting acceptable result (at least regarding our primary target, which was to have a fast 3D object for further modeling operations). As an example, I can report one of the last post of Cicero Moraes, who used SfM from a youtube clip to get a 3D skull for forensic facial reconstruction aims. The image below is taken from Cicero's photo album:
3D skull obtained with SfM techniques from a movie
For a better explanation of what I wrote above, I think it is worth to show the results of a project we are undertaking since 2005 (trying to support Prof. Tiziano Camagna on his exploration of Tovel's Lake, in Trentino). During this project we did several surveys, diving in different parts of the lake and especially in the South-West area, where lies a forest which is now underwater. In 2012 Tiziano Camagna and Andrea Forti, despite the low visibility, where able to record a short movie of some of the threes. We used this video for a fast 3D reconstruction, because it was particularly indicated, due to its characteristics: it was recorded for no SfM aims (as you see the movie sequences are not optimal for a 3D reconstruction), it represents the normal turbidity condition of the lake and it was done with an high lens distortion camera (GoPro Hero 2). For such reasons this material was perfect to hardly test SfM and IBM techniques for underwater archeology. In this animation you can see a short part of the movie (from the 15th second to the 25th), which we used for the 3D documentation...
From "La foresta sommersa del Lago di Tovel" (T. Camagna, A. Forti)
... and here you can see the result:
I hope this post was useful. Soon, when the season will allow us to start diving again, we will go on with tests and experiment related with underwater archeology. I hope to write soon some new report about it.
