The Iron-Age-Danube project (Monumentalized early iron age landscapes in the Danube river basin),... more The Iron-Age-Danube project (Monumentalized early iron age landscapes in the Danube river basin), co-financed by the Interreg Danube Transnational programme, is focused on the research, protection and sustainable touristic use of the archaeological heritage from the Early Iron Age in the Danube region. In the frame of the project two strategies, one on research and heritage protection and other on heritage promotion and touristic usage of archaeological landscapes, have been adopted. The strategies are combining a bottom-up analytical approach by incorporating the SWOT analysis from the eight micro-regions in four countries with a to-down approach by integrating the recommendations of the European Cultural Heritage Strategy for the 21st century (Strategy 21). The analysis showed 24 major challenges faced by the Iron-Age heritage, which can be tackled by 12 recommendations in the field of research and monument protection and 9 recommendations in the field of sustainable cultural tourism, divided to the S-D-K components introduced in the Strategy 21 and a newly established location component. Additionally, concrete courses of actions for stakeholders are listed, which enable practical implementation of recommendations. The strategies are accompanied by four national action plans for their implementation in Austria, Croatia, Hungary and Slovenia.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Feb 1, 2019
In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelt... more In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelters all over the Slovene Kras (or Karst) region. Despite being made out of stones that are interlocked without the use of any binding material, many of these vernacular constructions survived – even though sometimes only partially – the ravages of time. The fact that over one hundred fifty shepherd shelters are currently known is mainly due to the craftsmanship of their builders and thanks to (and even despite) their present location. A majority of these stone constructions can be found in areas that are nowadays forested, thus shielding them from weather-related or anthropogenic damage (because they are difficult to spot). This paper reports on the geometric documentation of those shelters using a photogrammetric computer vision pipeline, thereby mainly focussing on the difficulties that were encountered during this process. However, such image-based modelling approaches merely yield digital three-dimensional (3D) approximations of the shelters’ surface geometry (along with some sub-optimal colour data). Although these 3D surface models might be suitable to digitally preserve vulnerable vernacular buildings to some extent, they do not magically advance our understanding of them. The second part of this article focuses, therefore, on the extraction of archaeological information from these digital 3D constructions. More specifically, the total amount of stones, the total building time and the building cost regarding caloric energy expenditure are estimated for each of the digitised shelters. Although this assessment of architectural energetics provided useful insight into the building efforts and nutrient uptake of the shepherds, it also revealed many assumptions and shortcomings that often characterise archaeological information extraction from digital 3D models of buildings.
This paper presents the possibilities of implementation of image-based modeling procedures combin... more This paper presents the possibilities of implementation of image-based modeling procedures combining the Structure from Motion (SfM) approach with dense Multi-View Stereo (MVS) algorithms in a documentation workflow of rescue archaeological excavations. The primal focus is the evaluation of its advantages as well as its drawbacks with respect to the special needs and demands of documentation practice of rescue excavations. Further, the paper tries to pose questions on the relevance of 3D data acquisition and their subsequent exploitation possibilities. At the ongoing rescue excavations on the courtyard of the Bratislava castle and the area of Čachtice castle (Slovakia), such an image-based modeling approach was introduced into the existing documentation workflow. To assess the benefits and drawbacks of these relatively new techniques and compare them to the recording strategy used hitherto, the complete field documentation was carried out in a traditional way (i.e. total station measurements, still photography and 2D photogrammetry) as well as by applying an SfM+MVS approach using the software package PhotoScan Professional from Agisoft. Afterwards, both datasets were compared in terms of accuracy and interpretative value. Additionally, the time and financial costs needed to acquire basic data sets and produce the final archaeological documentation, were taken into account. With these comparisons, it is hoped that the benefits and drawbacks of image-based 3D modeling in the context of commercial archaeological rescue excavations will become clearer.
In order to overcome the different knowledge schemas of research on Neolithic and Chalcolithic si... more In order to overcome the different knowledge schemas of research on Neolithic and Chalcolithic sites of Greece and Anatolia, an open access Django-based database called DEFC App (Digitizing Early Farming Cultures Application) has been developed. The 3D models of the Schachermeyr sherd collection are one of the many resources that will be integrated into the database. The present contribution focuses on these 3D models and their metadata and on how they are contextualized within the DEFC App database and beyond. Additionally, we discuss the 3D model provenance metadata that should accompany the 3D models in order to assure their transparency.
Most people like 3D visualizations. Whether it is in movies, holograms or games, 3D (literally) a... more Most people like 3D visualizations. Whether it is in movies, holograms or games, 3D (literally) adds an extra dimension to conventional pictures. However, 3D data and their visualizations can also have scientic archaeological benets: they are crucial in removing relief distortions from photographs, facilitate the interpretation of an object or just support the aspiration to document archaeology as exhaustively as possible. Since archaeology is essentially a spatial discipline, the recording of the spatial data component is in most cases of the utmost importance to perform scientic archaeological research. For complex sites and precious artefacts, this can be a di€cult, time-consuming and very expensive operation.
In this contribution, it is shown how a straightforward and cost-eective hard- and software combination is used to accurately document and inventory some of the cultural heritage of the Cres/Lošinj archipelago in three or four dimensions. First, standard photographs are acquired from the site or object under study. Secondly, the resulting image collection is processed with some recent advances in computer technology and so-called Structure from Motion (SfM) algorithms, which are known for their ability to reconstruct a sparse point cloud of scenes that were imaged by a series of overlapping photographs. When complemented by multi-view stereo matching algorithms, detailed 3D models can be built from such photo collections in a fully automated way. Moreover, the software packages implementing these tools are available for free or at very low-cost. Using a mixture of archaeological case studies, it will be shown that those computer vision applications produce excellent results from archaeological imagery with little eort needed. Besides serving the purpose of a pleasing 3D visualization for virtual display or publications, the 3D output additionally allows to extract accurate metric information about the archaeology under study (from single artefacts to entire landscapes).
Mind your grey tones – examining the influence of decolourization methods on interest point extra... more Mind your grey tones – examining the influence of decolourization methods on interest point extraction and matching for architectural image-based modelling
This multi-touch book presents 3D models of selected early medieval earrings from the Župna cerke... more This multi-touch book presents 3D models of selected early medieval earrings from the Župna cerkev (Parish church) in Kranj (Slovenia) archaeological site. The book came about as part of an extensive research project analysing the site. In the process of documenting artefacts in a classic archaeological manner, that is with photography, archaeological drawings and textual descriptions, we also experimented with 3D documentation techniques that were available at the time. Due to restricted time that was available for 3D documentation, we focused on earrings as a predominant type of expressive artefacts on the site.
1 Introduction
2 Methodology of 3D digitisation in archaeology
2.1 3D digitisation in archaeology
2.2 3D digitisation in Slovenian archaeology
2.3 State of the art and a look into the future
2.4 A silhouette method and 3D documentation of early medieval earrings
3 The Site
4 The Artefacts
4.1Crescent-Shaped Earrings
4.2 Other Earrings
5 3D Catalogue
6 Bibliography
Settlements, Culture and Population Dynamics in Balkan Prehistory - ABSTRACTS OF THE ORAL AND POSTER PRESENTATIONS, Mar 9, 2015
HAEMUS - Center for Scientific Research and Promotion of Culture
http://haemus.org.mk
Settlemen... more HAEMUS - Center for Scientific Research and Promotion of Culture
http://haemus.org.mk Settlements, Culture and Population Dynamics in Balkan Prehistory
International Conference
13-14.03.2015
Skopje, Republic of Macedonia
ABSTRACTS OF THE ORAL AND POSTER PRESENTATIONS
General Editor: Vasilka Dimitrovska
Cover Design: Vasilka Dimitrovska, Elka Anastasova
Design: Elka Anastasova
Editing and English proofreading: Mark Branov
LBI ArchPro Symposium in cooperation with the Danube University Krems, Austria 2. – 3. April 2019... more LBI ArchPro Symposium in cooperation with the Danube University Krems, Austria 2. – 3. April 2019 at Danube University Krems The main objective of the symposium is to offer a multidisciplinary forum to discuss relevant topics and specific issues in cultural heritage protection and management and the application of digital methods for this purpose. The program shall encourage the scientific exchange and strengthen collaborative ties between participating institutions as well as increase the awareness of non-invasive methods in cultural heritage protection among stakeholders and the interested public. Session 3: Raising Awareness for digital methods for cultural property protection and cultural heritage management
Presented at the EAA 2017.
“Hiška” (also “šiška” or “kutja”), as local people call it, translate... more Presented at the EAA 2017.
“Hiška” (also “šiška” or “kutja”), as local people call it, translates to a small house. They were built of stone without any binding material and were used as a shelter for shepherds. These constructions are not unique to the Kras region (Slovenia) as similarly built structures are known all around Mediterranean area, stretching all the way to Britain on one edge and Near East on the other. Nevertheless, hiškas of the Kras region represent their own branch of dry-stone constructions and despite their long tradition (the dating is many times very difficult, if not impossible), today they stand hidden in the forest condemned to deteriorate. In the recent years several initiatives were taken to promote this type of cultural heritage, however, a lot still needs to be done. As a part of an ongoing PhD research several hiškas were recorded in 3D using image-based modelling technique with the main aim to use and test the collected 3D models not only for documentation and presentation purposes, but also to investigate the method itself as a tool for archaeological research. The documentation itself was a challenging task, as hiškas are normally located in a low-vegetation forest which makes it difficult to locate and document them. After 3D model acquisition the 3D models were used to compute volume to estimate the construction time and for simple simulations such as rain and sun to assess the functionality of different types of hiškas. Such 3D tools undoubtedly open new doors to archaeological interpretation, however, the collaboration between archaeologists and computer scientists needs to be promoted to increase the usability and application of acquired 3D models.
Verhoeven, G, Štuhec, S., Štuhec, I., 2019. Modelling building costs from 3D building models. 3D-ARCH 2019 "3D Virtual Reconstruction and Visualization of Complex Architectures", 07 February 2019, Bergamo, Italy. DOI: 10.5281/zenodo.2557762, Feb 7, 2019
In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelt... more In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelters all over the Slovene Kras (or Karst) region. Despite being made out of stones that are interlocked without the use of any binding material, many of these vernacular constructions survived – even though sometimes only partially – the ravages of time. The fact that over one hundred fifty shepherd shelters are currently known is mainly due to the craftsmanship of their builders and thanks to (and even despite) their present location. A majority of these stone constructions can be found in areas that are nowadays forested, thus shielding them from weather-related or anthropogenic damage (because they are difficult to spot). This paper reports on the geometric documentation of those shelters using a photogrammetric computer vision pipeline, thereby mainly focussing on the difficulties that were encountered during this process. However, such image-based modelling approaches merely yield digital three-dimensional (3D) approximations of the shelters’ surface geometry (along with some sub-optimal colour data). Although these 3D surface models might be suitable to digitally preserve vulnerable vernacular buildings to some extent, they do not magically advance our understanding of them. The second part of this article focuses, therefore, on the extraction of archaeological information from these digital 3D constructions. More specifically, the total amount of stones, the total building time and the building cost regarding caloric energy expenditure are estimated for each of the digitised shelters. Although this assessment of architectural energetics provided useful insight into the building efforts and nutrient uptake of the shepherds, it also revealed many assumptions and shortcomings that often characterise archaeological information extraction from digital 3D models of buildings.
This paper investigates the use of different greyscale conversion algorithms to decolourize colou... more This paper investigates the use of different greyscale conversion algorithms to decolourize colour images as input for two Structure-from-Motion (SfM) software packages. Although SfM software commonly works with a wide variety of frame imagery (old and new, colour and greyscale, airborne and terrestrial, large-and small scale), most programs internally convert the source imagery to single-band, greyscale images. This conversion is often assumed to have little, if any, impact on the final outcome. To verify this assumption, this article compares the output of an academic and a commercial SfM software package using seven different collections of architectural images. Besides the conventional 8-bit true-colour JPEG images with embedded sRGB colour profiles, for each of those datasets, 57 greyscale variants were computed with different colour-to-greyscale algorithms. The success rate of specific colour conversion approaches can, therefore, be compared with the commonly implemented colour-to-greyscale algorithms (luma Y’601, luma Y’709, or luminance CIE Y), both in terms of the applied feature extractor as well as of the specific image content (as exemplified by the two different feature descriptors and the various image collections, respectively). Although the differences can be small, the results clearly indicate that certain colour-to-greyscale conversion algorithms in an SfM-workflow constantly perform better than others. Overall, one of the best performing decolourization algorithms turns out to be a newly developed one.
3D digitisation techniques, especially image-based three-dimensional (3D) surface recording is a ... more 3D digitisation techniques, especially image-based three-dimensional (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 Early 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.
The Iron-Age-Danube project (Monumentalized early iron age landscapes in the Danube river basin),... more The Iron-Age-Danube project (Monumentalized early iron age landscapes in the Danube river basin), co-financed by the Interreg Danube Transnational programme, is focused on the research, protection and sustainable touristic use of the archaeological heritage from the Early Iron Age in the Danube region. In the frame of the project two strategies, one on research and heritage protection and other on heritage promotion and touristic usage of archaeological landscapes, have been adopted. The strategies are combining a bottom-up analytical approach by incorporating the SWOT analysis from the eight micro-regions in four countries with a to-down approach by integrating the recommendations of the European Cultural Heritage Strategy for the 21st century (Strategy 21). The analysis showed 24 major challenges faced by the Iron-Age heritage, which can be tackled by 12 recommendations in the field of research and monument protection and 9 recommendations in the field of sustainable cultural tourism, divided to the S-D-K components introduced in the Strategy 21 and a newly established location component. Additionally, concrete courses of actions for stakeholders are listed, which enable practical implementation of recommendations. The strategies are accompanied by four national action plans for their implementation in Austria, Croatia, Hungary and Slovenia.
ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Feb 1, 2019
In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelt... more In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelters all over the Slovene Kras (or Karst) region. Despite being made out of stones that are interlocked without the use of any binding material, many of these vernacular constructions survived – even though sometimes only partially – the ravages of time. The fact that over one hundred fifty shepherd shelters are currently known is mainly due to the craftsmanship of their builders and thanks to (and even despite) their present location. A majority of these stone constructions can be found in areas that are nowadays forested, thus shielding them from weather-related or anthropogenic damage (because they are difficult to spot). This paper reports on the geometric documentation of those shelters using a photogrammetric computer vision pipeline, thereby mainly focussing on the difficulties that were encountered during this process. However, such image-based modelling approaches merely yield digital three-dimensional (3D) approximations of the shelters’ surface geometry (along with some sub-optimal colour data). Although these 3D surface models might be suitable to digitally preserve vulnerable vernacular buildings to some extent, they do not magically advance our understanding of them. The second part of this article focuses, therefore, on the extraction of archaeological information from these digital 3D constructions. More specifically, the total amount of stones, the total building time and the building cost regarding caloric energy expenditure are estimated for each of the digitised shelters. Although this assessment of architectural energetics provided useful insight into the building efforts and nutrient uptake of the shepherds, it also revealed many assumptions and shortcomings that often characterise archaeological information extraction from digital 3D models of buildings.
This paper presents the possibilities of implementation of image-based modeling procedures combin... more This paper presents the possibilities of implementation of image-based modeling procedures combining the Structure from Motion (SfM) approach with dense Multi-View Stereo (MVS) algorithms in a documentation workflow of rescue archaeological excavations. The primal focus is the evaluation of its advantages as well as its drawbacks with respect to the special needs and demands of documentation practice of rescue excavations. Further, the paper tries to pose questions on the relevance of 3D data acquisition and their subsequent exploitation possibilities. At the ongoing rescue excavations on the courtyard of the Bratislava castle and the area of Čachtice castle (Slovakia), such an image-based modeling approach was introduced into the existing documentation workflow. To assess the benefits and drawbacks of these relatively new techniques and compare them to the recording strategy used hitherto, the complete field documentation was carried out in a traditional way (i.e. total station measurements, still photography and 2D photogrammetry) as well as by applying an SfM+MVS approach using the software package PhotoScan Professional from Agisoft. Afterwards, both datasets were compared in terms of accuracy and interpretative value. Additionally, the time and financial costs needed to acquire basic data sets and produce the final archaeological documentation, were taken into account. With these comparisons, it is hoped that the benefits and drawbacks of image-based 3D modeling in the context of commercial archaeological rescue excavations will become clearer.
In order to overcome the different knowledge schemas of research on Neolithic and Chalcolithic si... more In order to overcome the different knowledge schemas of research on Neolithic and Chalcolithic sites of Greece and Anatolia, an open access Django-based database called DEFC App (Digitizing Early Farming Cultures Application) has been developed. The 3D models of the Schachermeyr sherd collection are one of the many resources that will be integrated into the database. The present contribution focuses on these 3D models and their metadata and on how they are contextualized within the DEFC App database and beyond. Additionally, we discuss the 3D model provenance metadata that should accompany the 3D models in order to assure their transparency.
Most people like 3D visualizations. Whether it is in movies, holograms or games, 3D (literally) a... more Most people like 3D visualizations. Whether it is in movies, holograms or games, 3D (literally) adds an extra dimension to conventional pictures. However, 3D data and their visualizations can also have scientic archaeological benets: they are crucial in removing relief distortions from photographs, facilitate the interpretation of an object or just support the aspiration to document archaeology as exhaustively as possible. Since archaeology is essentially a spatial discipline, the recording of the spatial data component is in most cases of the utmost importance to perform scientic archaeological research. For complex sites and precious artefacts, this can be a di€cult, time-consuming and very expensive operation.
In this contribution, it is shown how a straightforward and cost-eective hard- and software combination is used to accurately document and inventory some of the cultural heritage of the Cres/Lošinj archipelago in three or four dimensions. First, standard photographs are acquired from the site or object under study. Secondly, the resulting image collection is processed with some recent advances in computer technology and so-called Structure from Motion (SfM) algorithms, which are known for their ability to reconstruct a sparse point cloud of scenes that were imaged by a series of overlapping photographs. When complemented by multi-view stereo matching algorithms, detailed 3D models can be built from such photo collections in a fully automated way. Moreover, the software packages implementing these tools are available for free or at very low-cost. Using a mixture of archaeological case studies, it will be shown that those computer vision applications produce excellent results from archaeological imagery with little eort needed. Besides serving the purpose of a pleasing 3D visualization for virtual display or publications, the 3D output additionally allows to extract accurate metric information about the archaeology under study (from single artefacts to entire landscapes).
Mind your grey tones – examining the influence of decolourization methods on interest point extra... more Mind your grey tones – examining the influence of decolourization methods on interest point extraction and matching for architectural image-based modelling
This multi-touch book presents 3D models of selected early medieval earrings from the Župna cerke... more This multi-touch book presents 3D models of selected early medieval earrings from the Župna cerkev (Parish church) in Kranj (Slovenia) archaeological site. The book came about as part of an extensive research project analysing the site. In the process of documenting artefacts in a classic archaeological manner, that is with photography, archaeological drawings and textual descriptions, we also experimented with 3D documentation techniques that were available at the time. Due to restricted time that was available for 3D documentation, we focused on earrings as a predominant type of expressive artefacts on the site.
1 Introduction
2 Methodology of 3D digitisation in archaeology
2.1 3D digitisation in archaeology
2.2 3D digitisation in Slovenian archaeology
2.3 State of the art and a look into the future
2.4 A silhouette method and 3D documentation of early medieval earrings
3 The Site
4 The Artefacts
4.1Crescent-Shaped Earrings
4.2 Other Earrings
5 3D Catalogue
6 Bibliography
Settlements, Culture and Population Dynamics in Balkan Prehistory - ABSTRACTS OF THE ORAL AND POSTER PRESENTATIONS, Mar 9, 2015
HAEMUS - Center for Scientific Research and Promotion of Culture
http://haemus.org.mk
Settlemen... more HAEMUS - Center for Scientific Research and Promotion of Culture
http://haemus.org.mk Settlements, Culture and Population Dynamics in Balkan Prehistory
International Conference
13-14.03.2015
Skopje, Republic of Macedonia
ABSTRACTS OF THE ORAL AND POSTER PRESENTATIONS
General Editor: Vasilka Dimitrovska
Cover Design: Vasilka Dimitrovska, Elka Anastasova
Design: Elka Anastasova
Editing and English proofreading: Mark Branov
LBI ArchPro Symposium in cooperation with the Danube University Krems, Austria 2. – 3. April 2019... more LBI ArchPro Symposium in cooperation with the Danube University Krems, Austria 2. – 3. April 2019 at Danube University Krems The main objective of the symposium is to offer a multidisciplinary forum to discuss relevant topics and specific issues in cultural heritage protection and management and the application of digital methods for this purpose. The program shall encourage the scientific exchange and strengthen collaborative ties between participating institutions as well as increase the awareness of non-invasive methods in cultural heritage protection among stakeholders and the interested public. Session 3: Raising Awareness for digital methods for cultural property protection and cultural heritage management
Presented at the EAA 2017.
“Hiška” (also “šiška” or “kutja”), as local people call it, translate... more Presented at the EAA 2017.
“Hiška” (also “šiška” or “kutja”), as local people call it, translates to a small house. They were built of stone without any binding material and were used as a shelter for shepherds. These constructions are not unique to the Kras region (Slovenia) as similarly built structures are known all around Mediterranean area, stretching all the way to Britain on one edge and Near East on the other. Nevertheless, hiškas of the Kras region represent their own branch of dry-stone constructions and despite their long tradition (the dating is many times very difficult, if not impossible), today they stand hidden in the forest condemned to deteriorate. In the recent years several initiatives were taken to promote this type of cultural heritage, however, a lot still needs to be done. As a part of an ongoing PhD research several hiškas were recorded in 3D using image-based modelling technique with the main aim to use and test the collected 3D models not only for documentation and presentation purposes, but also to investigate the method itself as a tool for archaeological research. The documentation itself was a challenging task, as hiškas are normally located in a low-vegetation forest which makes it difficult to locate and document them. After 3D model acquisition the 3D models were used to compute volume to estimate the construction time and for simple simulations such as rain and sun to assess the functionality of different types of hiškas. Such 3D tools undoubtedly open new doors to archaeological interpretation, however, the collaboration between archaeologists and computer scientists needs to be promoted to increase the usability and application of acquired 3D models.
Verhoeven, G, Štuhec, S., Štuhec, I., 2019. Modelling building costs from 3D building models. 3D-ARCH 2019 "3D Virtual Reconstruction and Visualization of Complex Architectures", 07 February 2019, Bergamo, Italy. DOI: 10.5281/zenodo.2557762, Feb 7, 2019
In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelt... more In the second half of the 19th and early 20th century, sheep shepherds have built dry-stone shelters all over the Slovene Kras (or Karst) region. Despite being made out of stones that are interlocked without the use of any binding material, many of these vernacular constructions survived – even though sometimes only partially – the ravages of time. The fact that over one hundred fifty shepherd shelters are currently known is mainly due to the craftsmanship of their builders and thanks to (and even despite) their present location. A majority of these stone constructions can be found in areas that are nowadays forested, thus shielding them from weather-related or anthropogenic damage (because they are difficult to spot). This paper reports on the geometric documentation of those shelters using a photogrammetric computer vision pipeline, thereby mainly focussing on the difficulties that were encountered during this process. However, such image-based modelling approaches merely yield digital three-dimensional (3D) approximations of the shelters’ surface geometry (along with some sub-optimal colour data). Although these 3D surface models might be suitable to digitally preserve vulnerable vernacular buildings to some extent, they do not magically advance our understanding of them. The second part of this article focuses, therefore, on the extraction of archaeological information from these digital 3D constructions. More specifically, the total amount of stones, the total building time and the building cost regarding caloric energy expenditure are estimated for each of the digitised shelters. Although this assessment of architectural energetics provided useful insight into the building efforts and nutrient uptake of the shepherds, it also revealed many assumptions and shortcomings that often characterise archaeological information extraction from digital 3D models of buildings.
This paper investigates the use of different greyscale conversion algorithms to decolourize colou... more This paper investigates the use of different greyscale conversion algorithms to decolourize colour images as input for two Structure-from-Motion (SfM) software packages. Although SfM software commonly works with a wide variety of frame imagery (old and new, colour and greyscale, airborne and terrestrial, large-and small scale), most programs internally convert the source imagery to single-band, greyscale images. This conversion is often assumed to have little, if any, impact on the final outcome. To verify this assumption, this article compares the output of an academic and a commercial SfM software package using seven different collections of architectural images. Besides the conventional 8-bit true-colour JPEG images with embedded sRGB colour profiles, for each of those datasets, 57 greyscale variants were computed with different colour-to-greyscale algorithms. The success rate of specific colour conversion approaches can, therefore, be compared with the commonly implemented colour-to-greyscale algorithms (luma Y’601, luma Y’709, or luminance CIE Y), both in terms of the applied feature extractor as well as of the specific image content (as exemplified by the two different feature descriptors and the various image collections, respectively). Although the differences can be small, the results clearly indicate that certain colour-to-greyscale conversion algorithms in an SfM-workflow constantly perform better than others. Overall, one of the best performing decolourization algorithms turns out to be a newly developed one.
3D digitisation techniques, especially image-based three-dimensional (3D) surface recording is a ... more 3D digitisation techniques, especially image-based three-dimensional (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 Early 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.
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Papers by Seta Štuhec
In this contribution, it is shown how a straightforward and cost-eective hard- and software combination is used to accurately document and inventory some of the cultural heritage of the Cres/Lošinj archipelago in three or four dimensions. First, standard photographs are acquired from the site or object under study. Secondly, the resulting image collection is processed with some recent advances in computer technology and so-called Structure from Motion (SfM) algorithms, which are known for their ability to reconstruct a sparse point cloud of scenes that were imaged by a series of overlapping photographs. When complemented by multi-view stereo matching algorithms, detailed 3D models can be built from such photo collections in a fully automated way. Moreover, the software packages implementing these tools are available for free or at very low-cost. Using a mixture of archaeological case studies, it will be shown that those computer vision applications produce excellent results from archaeological imagery with little eort needed. Besides serving the purpose of a pleasing 3D visualization for virtual display or publications, the 3D output additionally allows to extract accurate metric information about the archaeology under study (from single artefacts to entire landscapes).
Books by Seta Štuhec
1 Introduction
2 Methodology of 3D digitisation in archaeology
2.1 3D digitisation in archaeology
2.2 3D digitisation in Slovenian archaeology
2.3 State of the art and a look into the future
2.4 A silhouette method and 3D documentation of early medieval earrings
3 The Site
4 The Artefacts
4.1Crescent-Shaped Earrings
4.2 Other Earrings
5 3D Catalogue
6 Bibliography
http://haemus.org.mk
Settlements, Culture and Population Dynamics in Balkan Prehistory
International Conference
13-14.03.2015
Skopje, Republic of Macedonia
ABSTRACTS OF THE ORAL AND POSTER PRESENTATIONS
General Editor: Vasilka Dimitrovska
Cover Design: Vasilka Dimitrovska, Elka Anastasova
Design: Elka Anastasova
Editing and English proofreading: Mark Branov
Posters by Seta Štuhec
Presentations by Seta Štuhec
The main objective of the symposium is to offer a multidisciplinary forum to discuss relevant topics and specific issues in cultural heritage protection and management and the application of digital methods for this purpose. The program shall encourage the scientific exchange and strengthen collaborative ties between participating institutions as well as increase the awareness of non-invasive methods in cultural heritage protection among stakeholders and the interested public.
Session 3: Raising Awareness for digital methods for cultural property protection and cultural heritage management
“Hiška” (also “šiška” or “kutja”), as local people call it, translates to a small house. They were built of stone without any binding material and were used as a shelter for shepherds. These constructions are not unique to the Kras region (Slovenia) as similarly built structures are known all around Mediterranean area, stretching all the way to Britain on one edge and Near East on the other. Nevertheless, hiškas of the Kras region represent their own branch of dry-stone constructions and despite their long tradition (the dating is many times very difficult, if not impossible), today they stand hidden in the forest condemned to deteriorate. In the recent years several initiatives were taken to promote this type of cultural heritage, however, a lot still needs to be done.
As a part of an ongoing PhD research several hiškas were recorded in 3D using image-based modelling technique with the main aim to use and test the collected 3D models not only for documentation and presentation purposes, but also to investigate the method itself as a tool for archaeological research. The documentation itself was a challenging task, as hiškas are normally located in a low-vegetation forest which makes it difficult to locate and document them. After 3D model acquisition the 3D models were used to compute volume to estimate the construction time and for simple simulations such as rain and sun to assess the functionality of different types of hiškas.
Such 3D tools undoubtedly open new doors to archaeological interpretation, however, the collaboration between archaeologists and computer scientists needs to be promoted to increase the usability and application of acquired 3D models.
To verify this assumption, this article compares the output of an academic and a commercial SfM software package using seven different collections of architectural images. Besides the conventional 8-bit true-colour JPEG images with embedded sRGB colour profiles, for each of those datasets, 57 greyscale variants were computed with different colour-to-greyscale algorithms. The success rate of specific colour conversion approaches can, therefore, be compared with the commonly implemented colour-to-greyscale algorithms (luma Y’601, luma Y’709, or luminance CIE Y), both in terms of the applied feature extractor as well as of the specific image content (as exemplified by the two different feature descriptors and the various image collections, respectively).
Although the differences can be small, the results clearly indicate that certain colour-to-greyscale conversion algorithms in an SfM-workflow constantly perform better than others. Overall, one of the best performing decolourization algorithms turns out to be a newly developed one.
Theses by Seta Štuhec
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 Early 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.
In this contribution, it is shown how a straightforward and cost-eective hard- and software combination is used to accurately document and inventory some of the cultural heritage of the Cres/Lošinj archipelago in three or four dimensions. First, standard photographs are acquired from the site or object under study. Secondly, the resulting image collection is processed with some recent advances in computer technology and so-called Structure from Motion (SfM) algorithms, which are known for their ability to reconstruct a sparse point cloud of scenes that were imaged by a series of overlapping photographs. When complemented by multi-view stereo matching algorithms, detailed 3D models can be built from such photo collections in a fully automated way. Moreover, the software packages implementing these tools are available for free or at very low-cost. Using a mixture of archaeological case studies, it will be shown that those computer vision applications produce excellent results from archaeological imagery with little eort needed. Besides serving the purpose of a pleasing 3D visualization for virtual display or publications, the 3D output additionally allows to extract accurate metric information about the archaeology under study (from single artefacts to entire landscapes).
1 Introduction
2 Methodology of 3D digitisation in archaeology
2.1 3D digitisation in archaeology
2.2 3D digitisation in Slovenian archaeology
2.3 State of the art and a look into the future
2.4 A silhouette method and 3D documentation of early medieval earrings
3 The Site
4 The Artefacts
4.1Crescent-Shaped Earrings
4.2 Other Earrings
5 3D Catalogue
6 Bibliography
http://haemus.org.mk
Settlements, Culture and Population Dynamics in Balkan Prehistory
International Conference
13-14.03.2015
Skopje, Republic of Macedonia
ABSTRACTS OF THE ORAL AND POSTER PRESENTATIONS
General Editor: Vasilka Dimitrovska
Cover Design: Vasilka Dimitrovska, Elka Anastasova
Design: Elka Anastasova
Editing and English proofreading: Mark Branov
The main objective of the symposium is to offer a multidisciplinary forum to discuss relevant topics and specific issues in cultural heritage protection and management and the application of digital methods for this purpose. The program shall encourage the scientific exchange and strengthen collaborative ties between participating institutions as well as increase the awareness of non-invasive methods in cultural heritage protection among stakeholders and the interested public.
Session 3: Raising Awareness for digital methods for cultural property protection and cultural heritage management
“Hiška” (also “šiška” or “kutja”), as local people call it, translates to a small house. They were built of stone without any binding material and were used as a shelter for shepherds. These constructions are not unique to the Kras region (Slovenia) as similarly built structures are known all around Mediterranean area, stretching all the way to Britain on one edge and Near East on the other. Nevertheless, hiškas of the Kras region represent their own branch of dry-stone constructions and despite their long tradition (the dating is many times very difficult, if not impossible), today they stand hidden in the forest condemned to deteriorate. In the recent years several initiatives were taken to promote this type of cultural heritage, however, a lot still needs to be done.
As a part of an ongoing PhD research several hiškas were recorded in 3D using image-based modelling technique with the main aim to use and test the collected 3D models not only for documentation and presentation purposes, but also to investigate the method itself as a tool for archaeological research. The documentation itself was a challenging task, as hiškas are normally located in a low-vegetation forest which makes it difficult to locate and document them. After 3D model acquisition the 3D models were used to compute volume to estimate the construction time and for simple simulations such as rain and sun to assess the functionality of different types of hiškas.
Such 3D tools undoubtedly open new doors to archaeological interpretation, however, the collaboration between archaeologists and computer scientists needs to be promoted to increase the usability and application of acquired 3D models.
To verify this assumption, this article compares the output of an academic and a commercial SfM software package using seven different collections of architectural images. Besides the conventional 8-bit true-colour JPEG images with embedded sRGB colour profiles, for each of those datasets, 57 greyscale variants were computed with different colour-to-greyscale algorithms. The success rate of specific colour conversion approaches can, therefore, be compared with the commonly implemented colour-to-greyscale algorithms (luma Y’601, luma Y’709, or luminance CIE Y), both in terms of the applied feature extractor as well as of the specific image content (as exemplified by the two different feature descriptors and the various image collections, respectively).
Although the differences can be small, the results clearly indicate that certain colour-to-greyscale conversion algorithms in an SfM-workflow constantly perform better than others. Overall, one of the best performing decolourization algorithms turns out to be a newly developed one.
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 Early 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.