1. What is the Extended Matrix (EM) ?
The Extended Matrix is a formal language with which to keep track of virtual reconstruction processes. It is intended to be used by archaeologists and heritage specialists to document in a robust way their scientific activities. The EM allows to record the sources used and the processes of analysis and synthesis that have led from scientific evidence to virtual reconstruction. It organises 3D archaeological record so that the 3D modelling steps are smoother, transparent and scientifically complete. It has been developed by E. Demetrescu at CNR-ITABC (Rome). EM is at its 1.1 version (a 1.2 version is currently under development).
2. Yet another Formal Language ?
Virtual reconstructions in archaeology are, at times, considered “artistic” or “aesthetic” endeavors, as the complete list of sources used is not necessarily provided as a reference along with the 3D representation. The lack of a shared language with which the heritage experts could store and communicate the steps in the reconstruction process is, likely, one of the reasons for this situation. The goal of EM is to accomplish this task.
3. How does it work ?
The EM is based on the stratigraphic reading approach and aims to create a common framework connecting archaeological documentation and virtual reconstruction in the earliest stages of the excavation of a site or a 4D survey of a monument. A subset of the “classic” archaeological record-keeping concepts and tools such as the Stratigraphic Unit (or Context), the Activity, and the Matrix of Harris have been “extended” to include and define both re-constructive elements (like “lost” columns, friezes, capitals, etc..) and the sources on which they are based as well. The primary tools used are the Extended Matrix (EM) and the Virtual Stratigraphic Unit (or USV).
Schematics of the EM are available in the download section.
Full details can be found in E. Demetrescu, Archaeological stratigraphy as a formal language for virtual reconstruction. Theory and practice. Journal of Archaeological Science 57, pp. 42-55, 2015. [preprint download], [link to Science Direct], [BibTex].
4. In what scenarios it can be used the EM ?
EM helps archaeologists to collect and manage the archaeological record both during the excavation of a site and during a 4D survey of a monument. It provides a solid framework to store the stratigraphic data, the reconstruction hypothesis as well as the sources involved.
5. For what is NOT designed the EM ?
The objective of the Extended Matrix is not to propose solutions for the visualisation of the 3D model’s degree of reliability (such as gradient colors), but is rather to formalize the steps involved in each reliability evaluation and visualization: which sources have been chosen and how they have been used in the virtual reconstruction.
6. Three main ideas behind the EM:
- To make as closer as possible the virtual reconstruction record to the archaeological one as it is collected and interpreted on the field by the archaeologists (stratigraphy is extremely accurate when it comes to geometrical segmentation).
- To offer the easiest possible experience to “data creators” (specialists on antiquity) proposing a really usable metadata creation tool (based on just 10 nodes). The EM is smoothly recognised and adopted by archaeologists being just an extension of what they already do in their everyday activity. Metadata can be ingested directly during the field activities by archaeologists as well as by the modellers before and during the 3D content creation.
- To propose a system fully compatible both with digital born data (digital 3D survey) and with archaeological legacy data (documentation of old excavation campaigns) reducing human digitalisation errors during the ingestion.
7. EM and CIDOC-CRM
EM is not intended to replace already existing CIDOC-CRM based data collection tools. It is just wider in scope and, as a common language, it is focused in stimulate collaborative scenarios for archaeologists, information scientists, digital archeologists and engineers during all the steps involved in a reconstruction process (data collection, analysis and visualisation). The next version of EM (2.0) will provide an integration with CIDOC-CRM (or CHARM) in order to make easier data conversion tasks to other metadata schemas or libraries.
8. Software tools and file format for the EM
A good graph editor useful to draw an Extended Matrix is yED (free, multi-platform software) [link]
A complete EM template for yED can be found in the download section.
EM uses the GraphML file format (XML based) in order to be widely supported by other software tools and easily integrated in a custom workflow.