3D image of unique petroglyphs in Hunsrück
By means of high-resolution, three-dimensional documentation, the i3mainz supports the archaeological investigation of petroglyphs. Various recording techniques are used to document not only the petroglyphs themselves, but also to enable their integration into the environment.
In 2014, petroglyphs were discovered on a vertical slate wall in the Rhine-Hunsrück district. Different animals were pecked into the rock on an area of about 120 cm x 120 cm. The lines vary in depth, from a few millimetres to several centimetres. They are unique for Central Europe, so that a chronological classification must be made by means of comparable representations. These are mainly known from south-western France and Spain and date to the Late Palaeolithic.
In close cooperation with the GDKE, the RGZM and the archaeological association ARRATA, the i3mainz is endeavouring to secure this important find for the future. This is achieved through high-resolution, three-dimensional digital documentation. Various recording techniques are used to support the archaeological interpretation. On the one hand, archaeology would like to understand the production technique of the petroglyphs, and on the other hand, improve the readability of the representations themselves. In addition, the slate wall and the surroundings are documented three-dimensionally to also record the spatial context.
In March 2015, Stefan Mehlig (i3mainz) and Guido Heinz (RGZM) carried out supplementary recordings on site to the documentation already carried out in 2014. Terrestrial laser scanning was used to geometrically record the slate wall and the surrounding topography, and images of the petroglyphs were taken for photogrammetric procedures.
The P20 laser scanner from Leica was used to take the images with the terrestrial laser scanner. The location of the slate wall in the middle of dense forest made the recording complex. An area of about 50 m x 50 m was recorded with ten scanner standpoints. The superordinate coordinate system already established in 2014 served as the basis for georeferencing the point cloud. After processing the data and deleting all unnecessary points (especially trees), a coloured point cloud with an average point spacing of 1 cm is available. With this data it is possible to carry out further analyses in relation to the environment.
The images of the petroglyphs taken with a reflex camera are the basis for photogrammetric calculations using the SfM method. The 3D model with texture created from this is a supplement to the methods already used in 2014 (strip light projection and PTM).
The 3D model recorded in 2014 with the strip light projector was prepared for a 2.5 D view. With the Spatial Image Viewing and Analysis Tool (SIVT) created at i3mainz, this allows an analysis of different forms of representation through interactive lighting and transparency effects, different texture layers and other functionalities.
In addition to the final data processing, analyses as well as visualisations and presentations based on the recorded data are planned for 2016.