The devils boat

This year, thanks to Prof. Tiziano Camagna, we had the opportunity to prove our methodologies during a particular archaeological expedition, focused on the localization and documentation of the "devils boat". 

This strange wreck consists in a small boat built by the Italian soldiers, the "Alpini" of the battalion "Edolo" (nicknamed the "Adamello devils"), during the World War 1, near the mountain hut J. Payer (as reported by the book of Luciano Viazzi "I diavoli dell'Adamello"). 

The mission was a derivation of the project "La foresta sommersa del lago di Tovel: alla scoperta di nuove figure professionali e nuove tecnologie al servizio della ricerca” ("The submerged forest of lake Tovel: discovering new professions and new technologies at the service of scientific research"), a didactic program conceived by Prof. Camagna for the high school Liceo Scientifico B. Russell of Cles (Trentino - Italy).

As already mentioned, the target of the expedition has been the small boat currently lying on the bottom of lake Mandrone (Trentino - Italy), previously localized by Prof. Camagna and later photographed during an exploration in 2004. The lake is located at 2450 meters above see level. For this reason, before involving the students into such a difficult underwater project, a preliminary mission has been accomplished, in order to check the general conditions and perform some basic operations. This first mission was directed by Prof. Camagna and supported by the archaeologists of Arc-Team (Alessandro Bezzi, Luca Bezzi, for underwater documentation, and Rupert Gietl, for GNSS/GPS localization and boat support), by the explorers of the Nautica Mare team (Massimiliano Canossa and Nicola Boninsegna) and by the experts of Witlab (Emanuele Rocco, Andrea Saiani, Simone Nascivera and Daniel Perghem).
The primary target of the first mission (26 and 27 August 2016) has been the localization of the boat, since it was not known the exact place where the wreck was laying. Once the boat has been re-discovered, all the necessary operations to georeference the site have been performed, so that the team of divers could concentrate on the correct archaeological documentation of the boat. Additionally to the objectives mentioned above, the mission has been an occasion to test for the first time on a real operating scenario the ArcheoROV, the Open hardware ROV which has been developed by Arc-Team and WitLab.
Target 1 has been achieved in a fast and easy way during the second day of  mission (the first day was dedicated to the divers acclimation at 2450 meters a.s.l.), since the weather and environmental conditions were particularly good, so that the boat was visible from the lake shore. Target 2 has been reached positioning the GPS base station on a referenced point of the "Comitato Glaciologico Trentino" ("Galciological Committee of Trentino") and using the rover with an inflatable kayak to register some Control Points on the surface of the lake, connected through a reel with strategical points on the wreck. Target 3 has been completed collecting pictures for a post-mission 3D reconstruction through simple SfM techniques (already applied in underwater archaeology). The open source software used in post-processing are PPT and openMVG (for 3D reconstruction), MeshLab and CloudCompare (for mesh editing), MicMac (for the orthophoto) and QGIS (for archaeological drawing), all of them running on the (still) experimental new version of ArcheOS (Hypatia). Unlike what has been done in other projects, this time we preferred to recover original colours form underwater photos (to help SfM software in 3D reconstruction), using a series of command of the open source software suite Image Magick (soon I'll writ  a post about this operation). Once completed the primary targets, the spared time of the first expedition has been dedicated to secondary objectives: teting the ArcheoROV (as mentioned before) with positive feedbacks, and the 3D documentation of the landscape surrounding the lake (to improve the free LIDAR model of the area).
What could not be foreseen for the first mission was serendipity: before emerging from the lake, the divers of Nautica Mare team (Nicola Boninsegna and Massimiliano Canossa) found a tree on the bottom of the lake. From an archaeological point of view it has been soon clear that this could be an import discovery, as the surrounding landscape (periglacial grasslands) was without wood (which is almost 200 meters below). The technicians of Arc-Team geolocated the trunk with the GPS, in order to perform a sampling during the second mission.
For this reason, the second mission changed its priority an has been focused on the recovering of core samples by drilling the submerged tree. Further analysis (performed by Mauro Bernabei, CNR-ivalsa) demonstrated that the tree was a Pinus cembra L. with the last ring dated back to 2931 B.C. (4947 years old). Nevertheless, the expedition has maintained its educational purpose, teaching the students of the Liceo Russell the basics of underwater archaeology and performing with them some test on a low-cost sonar, in order to map part of the lake bottom.
All the operations performed during the two underwater missions are summarized in the slides below, which come from the lesson I gave to the student in order to complete our didactic task at the Liceo B. Russell.

Aknowledgements

Prof. Tiziano Camagna (Liceo Scientifico B. Russell), for organizing the missions

Massimiliano Canossa and Nicola Boninsegna (Nautica Mare Team), for the professional support and for discovering the tree

Mauro Bernabei and the CNR-ivalsa, for analizing and dating the wood samples

The Galazzini family (tenants of the refuge “Città di Trento”), for the logistic support

The wildlife park “Adamello-Brenta” and the Department for Cultural Heritage of Trento (Office of Archaeological Heritage) for close cooperation

Last but not least, Dott. Stefano Agosti, Prof. Giovanni Widmann and the students of Liceo B. Russel: Borghesi daniele, Torresani Isabel, Corazzolla Gianluca, Marinolli Davide, Gervasi Federico, Panizza Anna, Calliari Matteo, Gasperi Massimo, Slanzi Marco, Crotti Leonardo, Pontara Nicola, Stanchina Riccardo

Documentation of a bas-relief on a cliff : the workflow

This summer, between May and June, we worked for a joint mission, led by the University of Innsbruck (Institut für Alte Geschichte und Altorientalistik) and the Cultural Heritage, Handcrafts and Tourism Organization of Iran. The project was held in Firuzabad, in the Pars Province of Iran. We will write more details about this work in the next post. By now I just want to use some material we collected to illustrate the work-flow in data acquiring during an archaeological documentation of a bas-relief on a cliff.

The video below shows the overall process.

You can see the initial preparation phase (1), during which we placed the Ground Control Point (GCP) to perform normal 2D vertical photo-mapping and to rectify and georeference the 3D point-cloud. Than (2) we collected pictures with three different flights of our DIY drone, in order to use them with different open source SfM/MVSR software (PPT, openMVG and MicMac), to reach the best possible result: a couple of flights with parallel camera, to have a good superimposition of the whole bas-relief, and a higher acquisition to cover the upper details. In the meantime (3) another operator (+Rupert Gietl) was collecting pictures from the ground, to register also the lower perspective. Later (4), I prepared the total station and collected the GCP, thanks to some fixed points we placed the day befor (0) with our GPS. Finally +Rupert Gietl  took the last (very close) details photos, using a ladder.
The entire process lasted more or less four hours, but we needed some more time the day before to place the fixed GCP down in the valley (in international Geographic Coordinates System). A good part of the work involved just the logistics or the approach to the site, and has been slowed by the transportation of the necessary equipment (ladder, total station and drone) through a couple of passages where it was necessary to climb some rocks.
It is interesting to note that it would not have been possible to accomplish this mission with a commercial drone, due to the embargo rules (which are currently under revision), while with a DIY hexacopter it has been simple to disassemble the components which were not allowed (like the FPV system ore the GPS controlled flight).
I hope this post was useful, have a nice day!

Aerial images and videos of the WW1 trenches along the border between Austria and Italy

Hi all,

in the first days of October 2014, after a rainy summer, we have been engaged in taking aerial pictures and videos of the WW1 trenches in the border between Austria and Italy (villages of Kartitsch, Sexten/Sesto Pusteria and Comelico Superiore). The work was insert into a survey project financed by INTERREG funds. The trenches and military structures in the area of the project were mapped using a GPS (Trimble 5700); the most important and better preserved buildings were documented using different software (PPT, MicMac and OpenMVG) and particular hardware (aerial drone).

Thanks to Walter Gilli, our "flight instructor and drone developer", we have a new hexacopter that you can see in the picture below.

The main components are:

- a DJI NAZA-M V2 as flight controller

- a Spektrum DX8 as radio control

- a Sony Nex-7 as camera (24.3 megapixels)

- a StratoSnapper2 for the remote control of the camera (radio/IR)

- an Alexmos Gimsbal controller (2 axis) to stabilize the camera mount

- all mounted on a handmade frame

The video below shows the hexacopter flying in windy conditions. The high quality of the components makes this hexacopter a perfect instrument even in extreme situation.

The video below shows the a flight in optimal condition: a cloudy day without wind. The gimbal stabilizes the camera even during movements, ensuring a high quality result.

MicMac and PPT: two FLOSS solutions for 3D data

Hi all,
last week I finished my lectures in the Master Open Techne about Free Software and 3D data (acquisition and processing). As last year I could spend many times to research new solutions and test some applications. Some months ago, thanks to the friend +Romain Janvier , I was introduce to the use of MicMac, a suite for three-dimensional documentation of reality developed by the Institut national de l’information géographique et forestière (IGN). As Python Photogrammetry Toolbox, MicMac can produce point cloud from set of photos. There are two different ways to acquire images:

- the ground geometry mode (useful for zenithal pictures as a drone data-set or for wall's prospect) = take pictures perpendicularly to the surface (ground or wall) with 60 % of overlapping (between images and lines of image)

- the image geometry mode (useful for any kind of object that has more than one surface) = take a "cross" of images starting from the central one and then up, down, left and right; then take other images moving to the second position (frontal to another surface) and again a "cross" of image; go on in this way for all the surfaces of the object that you need to reconstruct.

The data acquisition is a little bit more complicate than PPT, both in the way to shoot and in the camera settings (keep the same level of zoom, no auto-focus, no stabilization, no flash, ...), but the final point cloud is denser. PPT is more user-friendly (thank to the python scripts and the GUI) but slower in processing data (mostly in the Camera Pose Estimation step of Bundler).

One of the advantages of MicMac is the fast developing that is improving the software and simplifying its usage. I'm waiting for the GUI ;)
Unfortunately Bundler and CMVS/PMVS have not new release since years.