Digitizing the excavation

The 21st Conference on Cultural Heritage and NEW Technologies (CHNT 21, 2016) took place in Vienna  the first week of November 2016. In that occasion we gave a presentation entitled "Digitizing the excavation. Toward a real-time documentation and analysis of the archaeological record". Today I found the time to publish it in our blog, to share our research regarding this topic and in particular some interesting projects of "archeorobotics" we are working on.

Here below you can see the video of the presentation, done like always with the open source software impress.js and Strut...

... and here is a short description of each slide:

SLIDE 1

The title (strictly related with Digital Archaeology in general)

SLIDE 2

A short presentation of Arc-Team

SLIDE 3

All the work has been done thanks to Free/Libre and Open Source Software. In order to keep going on with our research regarding archaeological methodology we need the source code!

SLIDE 4

The fundamental schema of the archaeological cognitive process elaborated by G. Leonardi in 1982. The schema shows the progressive reduction of the informations regarding human actions before and during the archaeological excavation (Human activities --> Traces on the soil --> Natural and anthropological degradation of the record --> archaeological excavation --> archaeological documentation) until the interpretative knowledge starts recover information during the post-excavation stage (with analitical data interpretation and reconstructive hypothesis)

SLIDE 5

A practical example of the schema from the site of Torre dei Sicconi in Italy (a medieval castle):

1. Human activities (summarized in the building of the castle, the medieval battle and the destruction of the main structure and the controlled explosion during the Great War)

2. Traces on the soil (summarized in the evidences of the battle, of the controlled explosion and of recent agrarian activities, while just negative layers were found regarding the construction of the structure)

3. Natural and anthropological degradation (summarized in the battle, the explosion, the agrarian activities and the normal natural dynamics)

4. Archaeological excavation (the most destructive investigation: in Torre dei Sicconi all the layers concerning the tower and the main central building has been removed by this activity)

5. The importance of archaeological documentation comes from distructive analysis (excavation). Being a long term project, Torre dei Sicconi was documented both with traditional and digital methodology

6. Data analysis. During this stage our knowledge of the site started to grow again. In this case both archaeological and historical techniques have been used

7. Reconstructive hypotheses represent the maximum increase of our (interpretative) knowledge of the site. For Torre dei Sicconi this stage has been achieved just for the central part of the castle (tower and main building)

SLIDE 6

The archaeological excavation is the most critical (destructive) stage of our knowledge regarding a site.

SLIDE 7

Arc-Team's excavation strategies:

1. increasing the amount of information registered decreasing the time-consuming operation of archaeological documentation

2. on-site direct observation for a better interpretation, avoiding at the same time any kind of data selection

3. moving the lab into the field (chemical and physical analyses)

SLIDE 8

A milestone of our research: in 2006 the development of the "Metodo Aramus" gave us a better (more precise and accurate), faster and corect (equalized) 2D digital documentation with FLOSS.

SLIDE 9

Another milestone. Between 2008 and 2009 the migration from pure photogrammetric software to SfM and MVSR methods (through the development of a GUI for +Pierre Moulon's application  Python Photogrammetry Suite) gave us better and faster 3D digital documentation

SLIDE 10

Even today we still use a combination of 2D and 3D techniques to meet different requirements of various archaeological projects

SLIDE 11

2D digital documentation through GIS is fast enough for on site interpretation during emergency excavation

SLIDE 12

A software like +QGIS  allows a direct interpretation on the field without the necessity of long post-rpocessing

SLIDE 13

3D documentation gives better results, but needs longer processing time (even if it does not need long data acquisition on the field, which is always performed)

SLIDE 14

We achieved (a lower quality) 3D data acquisition which has the fundamental characteristic of being real-time, thanks to open hardware (archeorobotics)

SLIDE 15

Our experience in archeorobotics dates back to 2006 with our first prototype of UAV, which could be use professionally just in 2008.

SLIDE 16

Currently or archeorobotics research regards our last prototype of Archeodrone (a UAV specifically designed for aerial archaeology)...

SLIDE 17

... some CNC machines and, above all, the Fa)(a 3D, a 3D open hardware printer which without any kind of modifications was able to satisfy our archaeological needs (like 3D printing casts of unique finds or exctract and print DICOM data form x-ray CT scan)...

SLIDE 18

... and the ArcheoROV, the open hardware Remotely underwater Operated Vehicle which we developed with the +Witlab Fablab 

SLIDE 19

Some pictures of the first test of the ArcheoROV

SLIDE 20

A first step into 3D real-time documentation through SLAM (Simultaneous Localization and Mapping) techniques has been done with the open source ROS (Robot Operating System) and RTAB-Map via Kinect...

SLIDE 21

... and tested for 3D real-time documentation in wooden areas (where SfM and MVSR or laserscab would have been too slow), reaching in almost one hour of work a model (with real dimension) of 75000 points.

SLIDE 22

A benefit of archaeorobotic system like these (which are ROS capable) is the possibility to change the sensor in order to adapt the hardware to different situation, using monocular or stereo cameras (for odometry) as well as LIDAR or SONAR devices.

SLIDE 23

Another benefit is the wide range of possibilities offered by the different open source software (e.g. RTAB-Map, LSD-SLAM, REMODE, Cartographer, ecc...)

SLIDE 24

Currently the precision/accuracy level of a real-time 3D archaeological documentation cannot be compared with the results achieved with post-processing through traditional SfM - MVSR systems, but there are good prospects for improvement.

SLIDE 25

Nowadays, basing on our professional experience, the best use of such devices seems to be during extreme operations, such as high mountain archaeology, glacial archaeology, underwater archaeology or speleoarchaeology

SLIDE 26

Another important step to improve the reaction time of professional archaeology, in order to avoid errors during the critical stage of the excavation, is the possibility to perform some basic archaeometrical analyses (chemical and physical) directly on the field.

SLIDE 27

Considering the composition of any archaeological layer based on two different elements, the skeleton (macroscopic) and the fine earth (microscopic), it is obvious that different analyses can be performed in different work environment.

SLIDE 28

For instance, in the case of the skeleton, a fast petrografic (ontoscopic) analysis can be easily performed directly on the field (defining allogeneic elements), while further (more specific) investigations need an equipped laboratory.

SLIDE 29

Also in the case of fine earth, some raw descriptive analyses can be performed on the field, while laboratory investigation can reach very detailed results (e.g. with the Scanning Electron Microscope).

SLIDE 30

The field analysis of the fine earth is more problematic (compared with the skeleton) the most common test (e.g. the Soil texture by feel) are anametric and subjective

SLIDE 31

For this reason, archaeometric test are the better choice (e.g the sedimentation test)

SLIDE 32

The sedimentation test on the field can be improved with basic physical analysis (e.g. considering the Stoke's Law in order to define sand, silt and clay by the tme they need to sediment)

SLIDE 33

Another implementation on the field for the sedimentation test is the possibility to directly store the data into a PostreSQL/PostGIS database (through some specific fields of the archaeological recording sheet), using the open source application geTTexture.

SLIDE 34

An example of the use of geTTexture

SLIDE 35

Other archaeometric test which are simple to perform directly during the excavation are based on basic chemical analyses, and specifically with the quantification of compounds like phosphates or nitrates.

SLIDE 36

Moreover, with some simple workarounds, it is possible to turn anametric (boolean) analyses of carbonates or organic substances, into metric (quantitative) observations.

SLIDE 37

The Archaeological excavation is a destructive process, subject to fatal (not reversible) errors. Moreover the reduced time and budget in professional and emergency archaeology increase stress conditions during decision making stages.
Real-time 3D mapping can speed up data interpretation, avoiding data selection on the field, while on-site chemical and physical analyses (geoarchaeology and archaeometry) can define a better (data-driven) digging strategy.


I hope this presentation can be useful. Have a nice day!

Kinect, a sleeping research branch reacivated

As you probably noticed, one of the topic of ATOR is related with hardware hacking, with the aim to build new archaeological devices from ordinary objects and tools (33).

This concept is close to the one of "reuse" (using an artefact for a purpose which is completely different from the original function), a pretty common phenomenon in archaeology; also in architecture there is something similar,  called "spolia" (but maybe our interest in hacking things is just a kind of McGiver syndrome of people grown up in the 80s).
However, this post is about hacking a common game device like Kinect to use its characteristic in archaeological 3D real-time documentation. If you are a regular reader of ATOR, you will know that we already face this challenge, performing a first test (1) with RGBDemo in February 2012, and controlling accuracy and precision of the device in March of the same year (2), after a discussion with some of the researchers of FBK, during the workshop "Low cost 3D: sensori algoriti e applicazioni". Due to the encouraging results achieved in our first experiments, we worked on the hardware in order to modify it for outdoor projects (3), but soon we experimented the limits of this technology when applied in areas with direct sunlight (4) or in documenting small objects (5, 25). Despite this drawbacks in our research, Kinect worked pretty good in indoor excavations (6), helping us in difficult situations (related with the the workplace safety), and for particular purposed, like for infra-red prospections in dark environment (7).
After all these experiences, our final advice about Kinect is that the device has a potential in archaeology, but its real employment in professional work is restricted to peculiar conditions, while in most of the cases the SfM-based techniques are the best option (due to their versatility, which makes them a perfect choice during missions abroad (8), for small finds documentation (9, 10), for underwater and aerial archaeology (11, 12, 13), considering also the speed which characterize SfM and MVSR open source software development (14) and the wide range of possibilities between the different tools (15, 16).
Well, at least this was our opinion until now... Currently we are changing our mind about Kinect, and this is due to our professional engagement in underground archaeology (17) and to our renovate interest in robotics. Let's deal with these two points separately.

Underground archaeology

Documenting an underground semisubmerged structure in Firuzabad (Iran)

Like any other operation in archaeological 3D documentation, the tolerance regarding accuracy and precision is variable and influenced by some factors, and mainly: research purposes, logistics, characteristics of the structures to be documented.
Without considering some important exceptions (e.g prehistoric rock shelter, which are often simple to document with SfM techniques), most of the structures related with underground archaeology (WW1 artificial caves, medieval mines, etc...) are connected with large scale survey projects (where it is important a "big data" approach, raising the tolerance in data acquisition to increase the number of documented structures); with logistically difficult areas (high mountains, glaciers, (18, 19) etc...); with structures often characterized by vast surfaces without important small details, which (when present) can be recorded with a targeted SfM or RTI (21, 22) documentation (e.g. for graffiti, inscriptions (20), manufacture traces, etc...). For this reason, in most of these projects, it is necessary to deal with precision in documenting (keeping checkpoints thanks to other TOF instruments, like total stations) in order to gain a real-time response from the selected device, and, under this point of view, Kinect is often a good solution, considering also that its infrared sensor helps very much in low light conditions (7).

Documenting WW1 caves in Southtirol (Italy)

Archeorobotics

Arc-Team's UAV during an aerial archaeology project in Storo (Trentino - Italy)

Since 2006, when we joined an aerial archaeological project in Armenia (23), we started to work on "archaeorobotics", trying to develop robotic devices able to help us in the most difficult archaeological missions.
The first positive results we reached in this field were related with aerial archaeology and the building of an open hardware UAV (in 2008), even if at the beginning we underestimated the time needed to practice with our new tool  (24). Soon our experience increased as we built different drones, based on open and closed solutions (like kk multicopter (26) or Naza dji (27) models). The benefits of this research branch were clear (28, 29) and soon other research institutions, like the CNR-ITAB of Rome (30), the University of Lund (31) and  the CNR-ISTI of Pisa (32), asked us to give lessons about this topic.
Another field of archaeorobotics we explored is the one related with CNC machines and especially with 3D Printers. For this topic a precious help came from the society Kentstrapper and Leonardo Zampi (aka +Exekias 87), who helped us in 3D printing the cast of the Taung Child (34, 35). Since RepRap project started (in 2005), 3D printers evolved very fast. Of course our interest regarding these machines is mainly oriented to Cultural Heritage, and this is also the reason why we built a Fa)(a 3D form scratch (36), but results with this kind of instruments can be very impressive, especially considering the wide range of scientific applications (37, 38, 39, 40, 41), even if sometimes you have to deal with difficult boolean operations (42).
However, none of the robotic projects we developed till now needed Kinect, being based on UAV, to 3D document archaeological sites, or on CNC machines, to fast replicate archaeological artefacts. Our renovate interest in Kinect for archeorobotics is due to our new challenge in developing a ROV (Remotely Operated Vehicle), in order to assist us in our underwater archaeological missions. Indeed, in the last months, we started a collaboration with the WitLab, the FabLab of Rovereto (Trentino - Italy), to develop a new Open Hardware ROV, especially designed for archaeological aims. One of the main topic in developing such an instrument is that the new robot will be oriented not only to 3D documentation, but also to the exploration of unknown areas. For such reason SfM and MVS software are no more enough, but we had to start again in testing Open Source SLAM (Simultaneous  Localization And Mapping) algorithms, due to the fact that we need to register in 3D the submerged landscape (Mapping), but also to recover the path the "ArcheoROV" did (Localization) to reach new hidden archaeological evidences (for a better planning of human operations).

Testing the ArcheoROV at night

Testing Open Source SLAM solutions

The importance of SLAM algorithms in exploring devices is the main reason why we started again to experiment Kinect. Indeed, despite Kinect cannot be used as an on-board optical device in our ArcheoROV (due to the infrared camera), this tool is the perfect system to check SLAM software.
If, you ever started in working on robotics, probably sooner or later you stepped into ROS (Robot Operating System), an Open Source (BSD License) collection of software frameworks for robots. Of course SLAM is a very important task for any robotic vehicle, and the ROS package RTAB-Map is a perfect solution to implement this capability into any autonomous or remotely operated machine, like our ArcheoROV. For this reason, before starting experiments in more sophisticated (and complicated) systems, we checked RTAB-Map performance with an old Kinect, and here is the video of the result:

As you can see, the performance of real-time 3D is pretty responsive, respect our old experiments with the Open Source software RGBDemo (also considering that the Kinect used in this video is the first version, and it is now pretty obsolete) and, most important, the localization function within SLAM algorithm works very good. As I wrote at the beginning of the post, our current impression is that this combination of hardware (Kinect) and software (ROS) can be a good solution for underground environment documentation, while the software can be the right choice for archaeological exploring robotic devices.

I hope that this long post will be useful, if you have any feedback, please just write your comment below. Have a nice day!

PS:

we will present the ArcheoROV at the ArcheoFOSS (43) of Cagliari (Sardinia - Italy), this year. Also our partner of WitLab will be with us!

Webography

ATOR:

(1) Kinect, real-time 3D; (2) Kinect accuracy and precision with RGBDemo; (3) Kinect 3D outdoor: hacking the hardware; (4) Kinect 3D outdoor: first test; (5) Kinect 3D limits: documenting small objects; Kinect 3D indoor: excavation test (6); Kinect - Infrared prospections (7); Aramus 2014: 2D and 3D documentation of archaeological excavation (8); 3D for archaeological finds (9); Taung Project: 3D with SfM & IBM (10); Extreme SfM: underwater archaeology (11); From drone-aerial pictures to DEM and ORTHOPHOTO: the case of Caldonazzo's castle (12); Documentation of a bas-relief on a cliff : the workflow (13); CMVS/PMVS2 40% faster (14); OpenMVG VS PPT (15); MicMac and PPT: two FLOSS solutions for 3D data (16); SfM for Underground Documentation (17); Archaeology as a profession (18); Glacial Archaeology: About the challange to work in extreme conditions (19); WW1: High Alpine Survey Data - Work in Progress (20); Arc-Team tries Large Scale Reflectance Transformation Imaging (RTI) (21); WebRTIViewer (22); UAVP (Universal Aerial Video Platform) (23); UAVP indoor flight (24); 3D documentation of small archaeological finds (25); Building an Xcopter (26); Arc-Team's UAVP: testing the NAZA dji (27); Xcopter drone and SFM techniques (28); ArcheOS and UAVP for archaeological remote sensing (29); Open Source Remote Sensing Platform (30); Remote sensing with UAV in archeology (lessons at Lund University) (31); Aerial archaeology with FLOS Hardware and Software (32); A DIY endoscope for emergencies during excavation fieldwork (33); 3D PRINTING THE PAST: SOME ISSUES (34); The Taung Child is now touchable, thanks to 3d printing (35); 3D printing for Cultural Heritage (36); Space archaeology (37); 3D PRINTING GOOGLE MAPS IS NOW EASY (38); When Veterinary Medicine and 3D printing meet each other (39); Three more animals are saved with the aid of Blender and 3D printing (40); Augmented Reality at Cultways (41); Boolean operations - the powerful Cork! (42); ArcheoFOSS 2016 in cagliari! (43)

Kentstrapper website: http://kentstrapper.com/

Fa)(a 3D website: http://www.falla3d.com/

WitLab website: http://www.witlab.io/

ROS website: http://www.ros.org/

RTAB-Map website: http://introlab.github.io/rtabmap/

The archaeometric excavation

Last year, on November 28, Arc-Team joined the conference "Lo scavo archeometrcio: scienza e tecnologia applicate allo scavo archeologico" (en: "The archaeometrcic excavation: science and technology applied to the archaeological excavation"), which was held in Rovereto (Italy) at the Museo Civico.

During the meeting we gave a presentation titled "Professional archaeology. Innovations and best practice with free technology. Toward an Open Research." Today I uploaded on our server the slides, so that we can share this work (like always under Creative Commons Attribution - CC BY).

As usual the presentation has been done with impress.js through the Graphical User Interface Strut (both GPL licensed) and it is optimized for Firefox or Iceweasel (better visualized here).

Here is a little explanation regarding the single slides:

SLIDE 1

A fast presentation regarding Arc-Team.

SLIDE 2

An animation representing the importance of geocoding in archaeology (from space to site).

SLIDE 3

Differential GPS and Total Station: the main tools needed by archaeologists on the field (to georeference every single element of the archaeological record).

SLIDE 4

Some examples of geocoding in archaeology: everyday work, project in extreme conditions and missions abroad...

SLIDE 5

... survay and excavations

SLIDE 6

In survay projects the geocoding tolerance for archaeology is higher, so that we are testing alternative solutions to build a low-cost and open source GPS with centimetric accuracy, using the software RTKLIB (or its port in Android)

SLIDE 7

All the recorded data (in 2D and 3D) can be imported into an open source GIS.

SLIDE 8

For aerial archaeology it since 2008 we are working with open source DIY UAV, like the UAVP or the KKcopter (in the slide).

SLIDE 9

Our last UAV prototype and an example of 3D pointcloud form aerial pictures.

SLIDE 10

Since 2014 we are testing DIY camera (using the filter of Public Lab) for NDVI and NGB pictures in archaeological remote sensing.

SLIDE 11

Just removing the IR filter, a normal camera can be used for endoscopic prospections in low light conditions.

SLIDE 12

In the field of geophysical prospections we use a DIY  machine for Electrical Resistivity Imaging. The data can be visualized in a GIS (e.g. GRASS GIS in the slide), using the east and north and the resistivity values.

SLIDE 13

Some geoarchaeological analyses can be performed directly on the field, like the settlement test (using the soil triangle) for the texture or the lithologic recognition for the skeleton.

SLIDE 14

Also some basic analytical chemistry can help during the excavation (giving indications on the ancient use of the soil), to verify the presence/absence of phosphates or of organic remains.

SLIDE 15

Other preliminary laboratory (flotation and sieving) analyses can prepare the samples for further investigation. Also in this case we use a DIY machine.

SLIDE 16

Colorimetry can be performed in many ways. Currently we are testing different options, like the open source spectrometer of Public Lab.

SLIDE 17

For some laboratory geoarchaeological analysis (e.g. microscopic morphology) we use normal optic microscopes, while for more advanced studies we externalize the service (e.g. SEM or energy dispersive x-ray spectroscopy)

SLIDE 18

Currently we are testing the potentialities of the FLOSS MorphoJ to speed up the process in carpological remains recognition

SLIDE 19

To document archaeozoological remains in the field, we use the standard digital documentation techniques (in 2 and 3D), with FLOSS (e.g. bidimensional photomapping with the Aramus method or 3D recording through SfM and MVSR)

SLIDE 20

In the evolutionary anthropology field we developed a new technique (anatomical deformation) thanks to the FLOSS Blender

SLIDE 21

The same software (Blender) is used in the process of archaeological forensic facial reconstruction

SLIDE 22

Open source GIS (e.g. GRASS) are the main software we use to process and manage the recorded data

SLIDE 23

Thanks to open source UAV and Blender we experimented new ways to disclose archaeological data in a four-dimensional way (x,y,z,t)

A more detailed explanation of the entire presentation will come soon with the related article. For the topics which were already discussed in AOTR, I suggest to read the related post (see the above bibliography). For the latest experiment (e.g. near infrared, NDVI and NGB; Electrical Resistivity Imaging; Sedimentation test; litologic recognition on the field; flotation and sieving; colorimetry; microscopic morphology; MorphoJ;), we will try to write something as soon as possible.

Bibliography

Lo scavo archeologico professionale, innovazioni e best practice mediante metodologie aperte e Open research (here on Research Gate and here in Academia)

Webography (from ATOR):

3D and 4D GIS

gvSIG

SfM and MVSR

PPT-GUI (tutorial); from pictures to mesh (PPT, MeshLab, Blender); PPT with Bundler MultiTread; PPT with turntable (not recomended); PPT VS MicMac; PPT VS openMVG; recovering old data; underground documentation; big data; low-light conditions; underwater archaeology; aerial 3D; 3D GIS; anthropology;

Aerial 3D documentation

Caldonazzo Castle (case of study);

Archaeological endoscopy

normal endoscopy; IR endoscopy;

Geoarchaeology

genetic color, framework and edge analyses of skeleton; analytical chemistry on the field;

Archaeobothany

Vegetal macro remains indentification;

Evolutionary anthropology
Anatomical Deformation Technique (ADT): validation; ADT Paranthropus boisei; ADT Homo rodhesiensis;

Archaeoanthropology
Archaeological Forensic Facial Reconstruction (AFFR); Digital AFFR: technique validation; AFFR: state of the arts; AFFR: poster;

Archaeological dissemination
Caldonazzo Castle 4D (case of study);

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.

Aerial archaeology with FLOS Hardware and Software

Hi all,

today I post an old presentation which I had no time to publish before. Its title is " Aerial archeology with FLOS Hardware and Software" and it is related with a lesson I gave during the Italian Virtual Heritage School 2013, held in Pisa at the headquarters of CNR. 

In my speech I tried to summarize Arc-Team's experience in aerial archeology from 2006 until July 2013. For this reason the slides are a little bit outdated, but the presentation still contains valuable informations for people who want to start with aerial related documentations with free and open source tools.

The first section of the slides is dedicated to an introduction about the two main component of our  Free and Open Source Remote Sensing Platform: ArcheOS (software) and an open source UAV (there are many option, like the UAVP, the ArduCopter, or the KK derivated copters).

The second part of the presentation shows the prototypes we built, both open source (UAV and KKcopter) and commercial (DJ Naza).

In the third branch I tried to summarize in a kind of "blueprint" animated infographic the main structure of a quadcopter. And later I simply repeated the post of ATOR in which Alessandro Bezzi described how to build an open source xcopter (KK board based).

In the fifth section are shown some possible quadcopters configurations, while in the sixth part is analyzed the evolution of the flight techniques (also considering different conditions that can influence the work).

Finally I presented some cases of study and, at the and, are just some tips based on our experience.

The presentation is embedded here below (just click on the window and press space to navigate). As usual in ATOR, it is released with CC BY, so if you need (also just some part of it), you can reuse the material in your work. I hope it can be useful.

For a better view, click here 

2016-04-26 Update

Thanks to self-archiving I can now add the bibliography related with this post:

 ResearchGate: Article

Academia: Article

I hope it will be useful, even if no more up to date it can be a starting point to work in Aerial Archeology with Open Software and Hardware.

From drone-aerial pictures to DEM and ORTHOPHOTO: the case of Caldonazzo's castle

Hi all,
I would like to present the results we obtain in the Caldonazzo's castle project. Caldonazzo is a touristic village in Trentino (North Italy), famous for its lake and its mountains. Few people know about the medieval castle (XII-XIII century) whose tower is actually the arms of the town. Since 2006, the ruins are subject to a valorization project by the Soprintendenza Archeologica di Trento (dott.ssa Nicoletta Pisu). As Arc-Team we participated in the project with archaeological field work, historical study, digital documentation (SFM/IBM) and 3D modeling.
In this first post i will speak about the 3D documentation, the aerial photography campaign and the data elaboration.

1) The 3D documentation 

One of the final aims of the project will be the virtual reconstruction of the castle. To achieve that goal we need (as starting point) an accurate 3D model of the ruins and a DEM of the hill. The first model was realized in just two days of field-work and four days of computer-work (most of the time without a direct contribution of the human operator). The castle's walls were documented using Computer Vision (Structure from Motion and Image-Based Modeling); we use Pyhon Photogrammetry Toolbox to elaborate 350 pictures (Nikon D5000) divided in 12 groups (external walls, tower-inside, tower-outside, palace walls, fireplace, ...).

The different point clouds were rectified thanks to some ground control point. Using a Trimble 5700 GPS the GCPs were connected to the Universal Transverse Mercator coordinate system. The rectification process was lead by GRASS GIS using the Ply Importer Add-on.

To avoid some problems encountered using universal coordinate system in mesh editing software, we preferred, in this first step, to work just with only three numbers before the dot.

2) The aerial photography campaign 

After walls documentation we started a new campaign to acquire the data needed for modeling the surface of the hill (DEM) where the ruins lie. The best solution to take zenithal pictures was to pilot an electric drone equipped whit a video platform. Thank to Walter Gilli, an expert pilot and builder of aerial vehicles, we had the possibility to use two DIY drones (an hexacopter and a xcopter) mounting Naza DJI technology (Naza-M V2 control platform).

Both the drones had a video platform. The hexacopter mount a Sony Nex-7; the xcopter a GoPro HD Hero3. The table below shows the differences between the two cameras.

As you can see the Sony Nex-7 was the best choice: it has a big sensor size, an high image resolution and a perfect focal lenght (16mm digital = 24 mm compare to a 35mm film). The unique disadvantage is the greater weight and dimension than the GoPro, that's why we mounted the Sony on an hexacopter (more propellers = more lifting capability). The main problem of the GoPro is the ultra-wide-angle of the lens that distorts the reality in the border of the pictures.
The flight plan (image below) allowed to take zenithal pictures of the entire surface of the hill (one day of field-work).

The best 48 images were processed by Python Photogrammetry Toolbox (one day of computer-work). The image below shows the camera position in the upper part, the point cloud, the mesh and the texture in the lower part.

At first the point cloud of the hill was rectified to the same local coordinate system of the walls' point cloud. The gaps of the zenithal view were filled by the point clouds realized on the ground (image below).

After the data acquisition and data elaboration phases, we sent the final 3D model to Cicero Moraes to start the virtual reconstruction phase.


3) The Orthophoto

The orthophoto was realized using the texture of the SFM's 3D model. We exported out from MeshLab an high quality orthogonal image of the top view which we just rectified using the Georeferencer plugin of QuantumGIS.
As experiment we tried also to rectified an original picture using the same method and the same GCPs. The image below shows the difference between the two images. As you can see the orthophoto matches very well with the data of the GPS (red lines and red crosses), while the original picture has some discrepancies in the left part (the area most far away from the drone position, which was zenithal on the tower's ruin).

4) The DEM

The DEM was realized importing (and rectifying) the point cloud of the hill inside GRASS 7.0svn using the Ply Importer Add-on. The text file containing the transformation's info was built using the relatives coordinates extracted from Cloud Compare (Point list picking tool) and the UTM coordinates of the GPS' GCPs.

After data importing, we use the v.surf.rst command (Regularized spline tension) to transform the point cloud into a surface (DEM). The images below show the final result in 2D and 3D visualization.

Finally we imported the orthophoto into GRASS.

That's all.

Remote sensing with UAV in archeology (lessons at Lund University)

Since 2011, Arc-Team is teaching during the course "digital archeology" at Lund University, introducing the class to the use of Free and Open Source Software (FLOSS) in archeology (with ArcheOS). The course is held by Nicolò Dell'unto (Department of Archaeology and Ancient History). 

This year we had the opportunity to give a lesson regarding the use of UAV (Unmanned Aerial Vehicles), and more precisely quadcopters,  in remote sensing projects. Our airfield was the Swedish village of Uppåkra, where the University is undertaking an excavation. 

Here you can see a coupe of video recorded in slow motion by our friends Carolina Larson and Stefan Lindgren of the Humanities Lab. Thanks to the slow motion, it is possible to observe the flight stability ...

... and the ability to maintain the position of the last drone we built (more details here).

The use of drones in the field of archeology has also attracted interest from the local press: the magazine of the University (LUM) published an article on the topic:

Radio-controlled helicopter maps
archaeological sites from above

DVF vs FPV

Hi all,
I received some mails asking me to explain better the differences between the flying techiniques I mentioned in the previous post.
I think that the two videos you can see below are better than too many words to describe this topic. The clips were registered durig our last aerial archaeological project, thanks to the help of Walter Morelli (the pilot).
 
In this movie it is possible to see the normal way to fly with a quadcopter (Direct Visual Flight). The pilot simply uses the radio-command looking directly the drone, correcting the flight from his point of view. It is the basic flying techniques, but it can be difficoult when the UAV is far away from the pilot. In fact, in this situation, it is not simple to understand where is the front or the back of the drone.

In this other (very) short movie we can see the FPV technique (First Person View), in which the pilot, thanks to special glasses, has the same point of view of the drone. This way to fly is optimal when a low-altitude flight is not enought and it is necessary to send the drone far away from the pilot.   

I hope it was useful. Bye

ArcheOS and UAVP for archaeological remote sensing

Hi all,

Finally I uploaded the presentation we did in the CAA Southampton 2012. Until our website is down (for maintenance), you can see it here. Inside you can find more details about the aerial archaeology project we mentioned in the post Xcopter drone and SfM techniques.

Here you can see the first slide, in the new Arc-Team theme I did playing with beamer, LaTeX :).

As you see the license is the Creative Commons Attribution 3.0 Unported (CC BY 3.0), which we are planning to adopt soon also for ATOR to facilitate content sharing.

2016-03-31 Update

Thanks to self-archiving I can now add the bibliography related with this post:

 ResearchGate: Articl

Academia: Article

I hope it will be useful, even if no more up to date it can be a starting point to work in Aerial Archeology with Open Software and Hardware.

CAA 2012, Southampton

This year the Computer Applications and Quantitative Methods in Archaeology (CAA) conference will be hosted by the Archaeological Computing Research Group in the Faculty of Humanities at the University of Southampton on 26-30 March 2012. Unfortunately we will have no time to stay the whole week in Southampton, but we will participate  to the session regarding "Novel Technologies For Supporting Archaeological Fieldwork" which will take place Wednesday, March 28. Our presentation ("Free and Open Source platform for remote sensing and 3D data acquisition") will focus on the combination of open source UAV (especially the UAVP drone) and ArcheOS. We will show as well some results about our last project of aerial archaeology in North Italy. 

I hope it will be an interesting experience (just to write some report about it). For more information about the congress, here is the official website: http://caaconference.org/.

Soon we will post the presentation, and some more details about our last research in UAV field.

2016-03-31 Update

Thanks to self-archiving I can now add the bibliography related with this post:

 ResearchGate: Article - Presentation

Academia: Article - Presentation

I hope it will be useful, even if no more up to date it can be a starting point to work in Aerial Archeology with Open Software and Hardware.

UAVP indoor flight

Just a fast comment about our experience with the UAVP. If you want to try to build your own DIY flying drone, do not underestimate (like we did...) the time you will need to practice with it and to become a good pilot. The whole project will take you through 4 steps:

1. build the frame (simple)
2. connect the electronic components (not so simple, you will need experience in soldering)
3. program the UAVP (to find the right configuration for your drone)
4. learn to fly (difficult)  

Anyway the last step is also the most fun! Just remember that there are different flying conditions (wind, outdoor, indoor) and it is better to practice with most of them. In the video below, you can see our first indoor flight (pretty different from outdoor open spaces).

UAVP (Universal Aerial Video Platform)

In 2006, during the Aramus Excavations and Field School, we had the possibility to partecipate in a subproject regarding the remote sensing of Aramus hill. The project was leaded by Ing. Klaus Kerkow with the help of Christine Hanisch. Luckily on that occasion there was the support of Armenian Ministery of Defence and of the Armenian Air Force, which provided an helicopter (as you can see in the picture), but, of course, this was an extraordinary situation.

The helicopter provided by Armenian Air Force

Since that year we tried to find a system to get remote sensing informations without the need of expensive or difficoult solutions (like helicopters or ultralight aircrafts). In 2008 we started a preliminary research which ended with the construction of an UAVP (Universal Aerial Video Platform), an open source UAV (Unmanned Aerial Vehicle). In the video below you can see the first flying test of our prototype (thanks to Wolfgang Mahringer, the main developer of UAVP project, who helped us in building our drone).