Layer-by-layer 3D documentation of a Hallstatt chamber grave in the form of a block excavation

Finished
Kammergrab Otzing i3mainz, CC BY SA 4.0

Since mid-2012, the Archäologische Staatssammlung München has been working in its restoration workshops on the block excavation of a Hallstatt chamber grave (7th century BC) from Otzing (Deggendorf district, Lower Bavaria) with a wealth of small finds, such as jewellery and other grave goods.

Motivation

It is assumed that this was a grave of a wealthy person. Numerous finds and grave goods such as ivory carvings and metal objects suggest this. The grave was discovered during the construction of a training ground. Most of it was recovered in one block and transported to Munich. Since 2012, the grave has been uncovered layer by layer, using technical aids such as an X-ray machine.

To support the archaeological documentation, each excavation state that is uncovered is recorded three-dimensionally with high precision (textured). Three excavation states are planned. Furthermore, special individual finds, e.g. grave goods, will be documented separately in three dimensions with a higher degree of detail.

Activities

The three-dimensional documentation of the features of Otzing was carried out with a strip light scanner (ATOS III), as it is very flexible with regard to the required 3D resolutions and also works in a high accuracy range. For the evaluation, a combination of 2D and 3D data was used, which will be incorporated into the documentation using a GIS system (Qantum GIS) and linked to a database. For this type of evaluation, 3D data alone are not sufficient, as they do not provide the complete range of information about the object, and therefore do not guarantee a complete mapping of the state of the excavation.

For this reason, an additional photogrammetric multi-image composite was created, which provides detailed colour information in addition to the 3D data. This additional information is used, for example, to localise and map different layers of the earth. The basis for these mappings is provided by 2.5D elevation models on the one hand and scaled orthoimage plans of the individual excavation states on the other.

Results

In 2012, the first excavation state was recorded and integrated into Quantum GIS as an elevation model and orthophoto. Subsequently, some representations were created in the form of edge separation, contour lines and relief shading. In 2013, the GIS data was connected to a simple database developed in consultation with the archaeologists in charge. Since a large number of unique and complex finds with very detailed and fine structures came to light during further excavation, the three-dimensional documentation of the next layer could only be continued at the beginning of 2015. On the one hand, the level of detail of the 3D measurement was increased (3D resolution of 0.25mm) and on the other hand, the resolution of the external texturing was adapted to the fine object structures. Finally, Tobias Reich created a small animation of the data, which depicts the exposure process and the unique find in a simple way. and the unique find in a simple way.