Uporaba trirazsežnostnega dokumentiranja za arheološko analizo stoječe vernakularne arhitekture (The Use of Three-Dimensional Documentation for the Archaeological Analysis of Standing Vernacular Architecture)
Creators: name: Štuhec, Seta
Publisher: name: Zenodo
Year: 2019
Subjects: subject: 3D
subject: Architectural energetics
subject: Architecture
subject: FOS: Civil engineering
subject: Biomechanics
subject: Caloric expenditure
subject: Computer vision
subject: Dry-stone
subject: IBM (Image-Based Modelling)
subject: Kras
subject: MVS (Multi View Stereo)
subject: PCV (Photogrammetric Computer Vision)
subject: SfM (Structure from Motion)
subject: Shepherd shelter
subject: Slovenia

description: Three-dimensional (3D) digitisation techniques, especially image-based 3D surface recording is a cost-efficient and intuitive technique that quickly gained ground in archaeological documentation during the 21st century, mainly because its execution became much more straightforward during the past decade. As a result, many archaeological 3D documentation projects suddenly saw daylight. The majority of the resulting 3D models serves heritage conservation and restoration purposes or is used to extract metrical information or morphological characteristics of the object under study. Since one could also obtain most of these outcomes using more traditional approaches, the value of 3D surface documentation in terms of archaeological analysis and interpretation is still not entirely clear. This dissertation questions, therefore, the added value of digital 3D models for archaeological knowledge gaining. It explores if these 3D surfaces can open up new analytical pathways that would otherwise stay closed. Since various archaeological sources usually require specific research methodologies, this dissertation solely focuses on vernacular dry-stone architecture found in the Slovene Kras region. Using twenty-two image-based 3D surface models of shepherd shelters dating to the Late Modern Era, the author tries to answer questions about the functionality and biography (i.e. construction and use) of these shelters, thereby demonstrating the (in)effectiveness of 3D documentation as a starting point for this type of archaeological analysis. To unravel which properties best served the shelters’ function of protection against environmental factors and research how their use was affected by this suitability to protect, several analytical approaches were taken. All possible inner and outer dimensions of the 3D shelter models were measured, their volume of construction material and interior space calculated, various cross sections extracted and their surfaces checked for possible traces of usage wear. Besides, the influence of the environment (i.e. sunshine and rain) on these dry-stone constructions was virtually simulated, and 3D shepherd figures were digitally placed inside them. The newly obtained data made it clear that all shelters were performing their function virtually equally-well. The level of usage of the shelters could only be inferred from the detailed digitised 3D surfaces. Not only was it possible to observe traces of wear on the surface of the digital shelters, but the latter also enabled the quantification of the erosion and compaction of the soil inside every shelter due to the repeated walking on its floor. The orientation of the entrance was the only characteristic related to the shelters’ usage. Frequently used shelters feature a southwest entrance, which provides the best protection against the north-eastern burja wind, while additionally appearing favourable in the case of the incoming sunlight. The 3D models also proved essential to estimate each shelter’s stone mass and compute their centre of gravity. Both pieces of derived data served as the foundation for determining the shelters’ temporal and metabolic building costs. With an estimated caloric expenditure of 660 kcal per building day, the construction of most shelters was not very demanding nor did it necessarily involve a change in the dietary intake of the shepherds. The exception to this are larger shelters, for which the construction took many person-days. In these cases, one can assume a slight increase in food intake or less working hours per day. However, the construction could also be carried out over a more extended period (i.e. during many non-consecutive days) or just by multiple builders. Finally, the analytical potential of these digital shelter models has also been exhibited by populating them with 3D models of sitting or standing adult and child shepherds. In this way, the maximum number of shepherds that fit per shelter while not positioned with their back to each other was determined, thereby also simulating possible ways of communication. Besides the potential to extract new data and deduce original insights from archaeological 3D surface models, their analytical usage also brings a whole set of specific problems and considerations along. Some of those can be tackled if one knows how the 3D surface model was generated (which means that the photo acquisition, model generation and processing stages should be carefully documented). It is, for instance, impossible to directly compute if these dry-stone shelters could keep their inhabitants dry, simply because image-based modelling is unable to digitise all the cavities between the stones. However, simulating surface water run-off to detect concave regions that would collect water – and thus make it more likely for the structure not to be waterproof – is still possible. Moreover, data generated by a computer does not give these data an explicitly or inherently greater importance than their analogue counterparts, nor does the (potential for) high geometrical accuracy of 3D surface models render them ‘more objective’. Creating and analysing digital 3D surface models is still subject to many technical and interpretive decisions, which influence both the end-result and the newly derived insights. For example, calculating the volume of stone material is impossible without estimating the shelter’s boundaries. However, delineating shelters from their natural environment or shared dry-stone constructions (such as a wall) is highly interpretative. 3D documentation as a data generation tool for archaeological analysis and interpretation of vernacular architecture thus proved to be challenging and promising at the same time. Only time will tell if the analytical potential of such 3D surface data will be embraced and exploited by archaeologists to yield insights that are not obtainable using other means. The primary challenge still faced by many field archaeologists that deal with digital 3D surface data lies in intensive collaboration with geomatics professionals. Such collaborations would enable a better understanding of the data recording particularities and analytical possibilities offered by the latest 3D technologies. Moreover, the geomatics industry could develop the software tools that enable the analyses envisioned by the heritage professionals. At the same time, the geomatics professionals often resort to cultural heritage examples to merely showcase their innovations in 3D surface recording. Although this yields an enormous quantity of digitised geometry, such 3D surface records do not inherently possess any added value for archaeological research, nor do they help to solve other significant issues like data accessibility, metadata standardisation and photo acquisition protocols. The problem that arises here is thus twofold. Archaeologists and other cultural heritage specialists often use digital 3D data in unimaginative or even inappropriate ways due to lack of technical understanding and interdisciplinary separation, while pertinent archaeological questions and heritage-specific problems usually get excluded from the 3D digitisation wave preached and practised by the geomatics industry. Breaking this vicious circle will take much patience and can only become a reality upon intensified cooperation (and not just communication!) between the two professions.
description: This document is the doctoral thesis of Seta Štuhec, which was defended on the 27th of June 2019. This thesis is written in Slovene, with an abstract in English.