4D in archaeology: 3D documentation VS 3D reconstruction

 Hi everybody,

On 23 April 2020 I was asked by my friend Piergiovanna Grossi to give a lesson about 3D and archaeology at the University of Verona. Unfortunately I cannot share here this lesson (at least not yet), due to some restrictions. Nevertheless I would like to write a fast post about one of the topics that seem to have surprised the students: the difference, in archaeology, between 3D documentation and 3D reconstruction.

To keep it simple (KISS principle) we have to consider that we can define our reality (at least in a simple way) in 4D, through three spatial dimensions (x,y,z) and a temporal dimension (t). For this reason, when we work on an archaeological project (excavation, survey, etc...) and we want to document something, we have to pay attention that we are not simply registering the data in 3D, but we are doing a digital copy of the object of our investigation, during a specific time lapse, so that we are recording his physical aspect (morphology) as it is at the moment in which we are working on it. In other words, we are recording a 3D of the object as we see it now (but it would be more correct to say that we are recording it in 4D: x,y,z and t). This is what we call archaeological documentation, but we have to keep in mind that the object as we see it can be very different from the shape it had in the past (like the ruins of a castle are different from the castle itself). Moreover we have to consider that a single object may have had various shapes in the past (a castle could be the result of various architectural stages). This is lead us to the main difference between an the archaeological documentation (which record the object as we see it when we study it) and the archaeological reconstruction (which tries to rebuild the original shape of the object in the past).

This difference is important also because, in Digital Archaeology, 3D documentations  and 3D reconstructions are performed with different kind of software. In the first case we can use SfM-MVS techniques with FLOSS like MeshRoom, OpenMVG, etc..., while in the second we use 3D suite like Blender, even if, recently, Cicero Moraes wrote an add-on able to join this two aspects into a single application: OrtgogOnBlender.

Of course, working in Arc-team together with Cicero Moraes, it is obvious for me to mention him for this topic, but this is due not only to his effort in developing OrtogOnBlender, but also because, in order to explain the students this fundamental difference between archaeological documentation and reconstruction, I found out that the best way was to  show the some example of our past projects related with Forensic Facial Reconstruction (FFR). In fact I started showing some example regarding the medieval of Torre dei Sicconi and the roman site of Villa di Valdonega, like the image below...

 

The Roman site of Villa di Valdonega: 3D documentation (up) and 3D reconstruction (down)

... but suddenly everything was more clear when I showed an example of FFR, like this one:

 

The FFR of St. Valentine of Monselice: on the left side the reconstructive model, on the right side the documentation of the skull

Indeed, during an archaeological FFR project, it is pretty simple to understand that the 3D of the skull represent a 3D documentation, while the 3D of the face is a 3D reconstruction.

I hope this post was useful, Have a nice day!

VirtualArch: a mobile App to valorize the medieval mines of Mt. Calisio

Hello everyone,

this post regards an European Project we worked on this year: VirtualArch. The aim of this project was the tourist enhancement of some European sites characterized by an hidden (not directly visible) Cultural Heritage.

Our task was to find a way to show the medieval mines of Mt. Calisio, near the city of Trento. Most of these silver mines are not yet open to visitors and are hidden under some interesting cultural paths, created by the Ecomuseo Argentario (the ancient name of Mt. Calisio). In order to allow tourists to understand this interesting hidden heritage, we developed a mobile app, which guides the visitors through three paths, showing information about the ancient mines and their cultural landscape.

The first problem to solve was the interoperability of the app, which had to run on different mobiles (with Android, IOS, Windows, etc...). Our solution has been the development of an open source App (here the code), based on internet language, in order to be visualized without problem on most of the mobile, regardless on the Operating System. We also had to produce most of the multimedia content and, as requested by our customer (The Archaeological Office of the Autonomous Province of Trento), we rendered several 4D video regarding the life in the silver mines during Medieval age. We prepares this material with our 3D expert Cicero Moraes, thanks also to the technical advices of Dr. Nicoletta Pisu (Archaeological Office) and Dr. Lara Casagrande (Ecomuseo Argentario).

The App can be downloaded with a mobile device at this link. Due to the fact that, currently, on Mt. Calisio there is no internet, the App should be completely downloaded on the device before to reach the site. For some tasks, the App will ask to use specific devices on mobile systems, like the GPS (to track the position on the paths) or the camera (to be used for Augmented Reality). Being based on an internet language (PHP, JS, etc...), the same link will also show the App on normal computers, but without optimization for texts, images and videos.

If you want to have a preview of this App, you can simply watch the three videos here below, showing the three cultural paths and their Points Of Interest (POI).

SENTIERO DELLE GRAVE / GRAVE'S PATH

This cultural paths is called "Sentiero delle Grave" and crosses three POI (Points Of Interest) of a cultural landscape due to the unloading of silver mining waste, which made the surrounding woods more like a savannah.

POI 1: text and images about the animals living in this habitat

POI 2: text, images and video (a flight with a drone) about the anthropic landscape of the "Grave"

POI 3: text and images about the flora of the "Le Lore" peat bog

SENTIERO DEGLI GNOMI / GNOMES PATH

This paths is called "Sentiero degli gnomi" and crosses five POI (Points Of Interest) of natural and cultural landscape related with the figure of gnomes and dwarfs, historically (locally) deriving from the "canopi", the ancient miners.

POI 1: text, images about the "Canopi" (medieval silver miners) and the derived figures of the folklore (gnomes and dwarfs), with a 360° panoramic view (the damages of the storm "Vaia" on the wood).

POI 2: text and images about the local lime kiln

POI 3: text and images about the "Montegpiano's peat bog" flora.

POI 4: text and images about the dress of the "Canopi" and about the local mine called "Canopa del Raita", with a video showing the exploration of its caves.

POI 5: text and images about the local mine of the "Dos del Cuz", with a slider showing the superimposition of an aerial orthophoto over the LIDAR 3D model and the map of the caves. A 3D video shows the old work outside the mines.

SENTIERO DELLE CANOPE / CANOPE'S PATH

This paths is called "Sentiero delle Canope" and crosses eight POI (Points Of Interest) of a cultural landscape related with the ancient silver mines (called "Canope") of Mt. Calisio.

POI 1: text and images about the S. Colomba's lake and the surrounding area, characterized by many mine shafts, visible in the slider showing the superimposition of an aerial orthophoto over the LIDAR 3D model of the area.

POI 2: text and images about the ancient tools used by the miners ("Canopi"), visible within a gallery, with an interactive 3D model (in 3DHOP), showing the work under the surface.

POI 3: text and images about the local "Canopa delle Acque", with a video showing a virtual tour inside the mine.

POI 4: text and images with some technical information about the geology of the area, with a 3D video showing a section of the mountain with the "Canopa delle Acque"

POI 5: text and images about the local "Canopa dell'Uccello", with a gallery about the minerals of the area.

POI 6: text and images about the local "Canopa dei Bamponi"

POI 7: text and images about the panorama visible from the belvedere, with some information about the archaeological site of the "Redebus" (gallery) and about the historical Erdemolo's mines (Miniere di Erdemolo / Gruab va Hardimbl)

POI 8: text and images with technical information about the ancient excavation methods, with an Augmented Reality application to show 3D models of ancient tools.

I hope this post was useful.

If you want to try the App (also without visiting the sites) and you are not an Italian speaker, there is an English translation done by Claudio Parisi (just download the App and choose the English option).

Have a nice day!

QGIS Time Manager, for archaeological time series

Hi all,

I am back from the CHNT conference, which was held, like every year, in Vienna. There I had many feedbacks and the possibility to speak with colleagues regarding common problems in our profession (soon I hope to report some feedbacks from the session I was attending). 

Today I would like to write a fast post about time visualization in GIS for archaeological aims, because I was asked by our friend +Undine Lieberwirth  if we ever faced with this topic and especially if we ever used TGRASS. The answer is yes and this reminded me that we never wrote something about it, so I would like to start here a series of post dedicated to chronological GIS visualization with open source GIS in general (and in particular about some non conventional and alternative use of it), considering also the 4D visualization tasks.

By the way, today I will start with something simple, just showing an interesting tool of +QGIS : the  Time Manager plugin.

The video below is just a fast demonstration of this tool, with some data coming from an excavation we performed between 2009 and 2011 in the church of S. Giovanni at Massimeno. The raster time series regards the different architectural phases of the structure (from XI to XXI century) we recognized during the excavation.

That's all for now. Have a nice day!

Digital Archaeology at Lund University

This year, as usual since 2011, +Alessandro Bezzi and me taught some lessons during the course "Archaeology and Ancient History: Digital Archaeology, GIS in Archaeology" at Lund University, held by +nicolò dell'unto. We used the opportunity to update the presentation with which we always start the first lecture. Here below you can see its last version, done with impress.js (just click on the first slide and us the spacebar to navigate).

For a better view, click here

The main topic is digital archeology (or "computational archeology", as it is also known in Italy). 

Initially we define five main operations that are common to any archaeological project: data acquisition, processing, management, analysis and sharing. The first three steps refer to the documentation work-flow, while the last three actions are related with the real research process (of course data management is in common with both of the phases).

Thereafter we analyze each step, starting with data acquisition, which is mainly based on hardware devices. During this operation are normally registered two elements, points and pictures, in order to virtually recover what the archaeological excavation is destroying. With points and pictures it is possible to document objects (artifacts and ecofacts) and actions (basically the archaeological samplings), and their elaboration or, in some cases combination, allows the researchers to record lines, polygon, 3d surfaces and real volumes, to register also the most complex elements of the archaeological record (layers, structures, etc...).

On the contrary of what happen with data acquisition, data processing is mainly based on software. Nowadays it can be divided into two orders of operations: standard procedures (raw coordinates elaboration, 2D photomapping, 2D vector archaeological drawing) and advanced techniques (3D restitution, volume calculation and 3D modeling). The very first and basic step to visualize recorded data is to elaborate the raw coordinates, registered with a total station or a RTK GPS, into a GIS readable code (e.g. CVS or WTK). Combining points and pictures is also possible to create georeferenced photomosaic, using a photomapping techniques (e.g. the metodo Aramus, the Khovle method or the newest Corte Inferiore method). Once obtained a complete georeferenced photomosaic it is possible to use a GIS to draw over the raster level, using one or more vector layers and to connect them with a database. Advanced techniques of documentation are more directly related with 3D and can be based on different methodology to extract morphological, topological and metric informations from one or more pictures (e.g. SvR, SfM, IBM, 3D photogrammetry, etc...). With these informations it is possible to calculate the real volumes of the elements of the archaeological records and use this data to reconstruct the depositional and post-depositional processes, using, when necessary, 3D modeling. Normally, during the different work-flows that can be involved in data processing, many kind of informations are elaborated with raster, vector and voxel graphic in 2 (x,y), 3 (x,y,z) or 4 (x,y,z,t) dimensions. The final aim is to set up a system which is able to handle such a variety of data and this system is the GIS.
In fact GIS software, combined with DBMS, are extremely useful during the data management phase, exactly for their capacity to handle different kind of informations (as many as are the disciplines or sciences which help archeology in its task). The use of such instruments helps to optimize the research, especially in comparison with the traditional techniques, not only during data management, but also during the more delicate stage of data analysis (when most of the cognitive processes are involved).
Among other things, in this fourth step, it is more evident the importance of using open source software and tools to maintain a continuous control on every single process of a study that can lead to the elaboration of new theories. Of course, not all the the analysis are equally sensitive under this aspect: for the simplest researches (anastylosis, building techniques, basic geomorphology, etc...) it is not strictly mandatory to know the source code of the applications, also because in these cases the main examinations are done directly by humans. On the other hand, for more complex studies (landscape archeology and Cost Surface Analysis, statistics, advanced geomorphology, etc...), it is very important to have a complete access to  the formulas and algorithms used by the software in order to keep an human control and do not completely delegate to the computer, among difficult quantitative calculations, also more delicate qualitative investigations (in which the human operator is still essential). In this way it is possible to correctly study all the different informations collected during the archaeological research, considering, at the same time, future integrations (GIS is an open system under a temporal point of view). The last goal of data analysis is to share results with the (scientific and non) community, which is the best way to improve the archaeological discipline itself, especially exploiting the potential of internet.
This lead us to the final step of an archaeological project (data sharing), which can follow different channels, like traditional publication, e-publication (e.g. webgis), exhibitions, etc... The most important thing, at least for scientific disclosure, is to grant a public access to all the informations used for the study (not only the filtered data, but also the raw data), in order to propose new hypothesis and (at the same time) give the all the necessary elements to verify them (no dogma, no authority principle).
To summarize the meaning of this contribution, considering archeology as a science (empiric approach) and a humanity (speculative approach), we can see how computational archeology helps to improve the scientific (empiric) approach, which is often underestimated, granting a more objective data acquisition and processing respects traditional techniques, especially during the critical phase of the archaeological excavation. In fact, unlike scientific experiments, the archaeological excavation is unrepeatable, being the most destructive approach of the discipline (and, at the same time, the most important).

PS

All the screenshots were done with ArcheOS. Some of them are related with really old projects, slowly we will replace them with more updated images...