Thursday, 27 February 2014

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...

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