Creation of a deformation-compliant measurement of the City Wall

The ancient city wall of Kronach in Germany, known as the Stadtmauer, is a defensive structure built of sandstone blocks that surrounds almost the whole of the old town. The wall dates from around 1300 and was first mentioned in documents in 1323/24. For the project of documenting and monitoring the ancient wall, a modern digital approach was used to create an accurate 3D model serving the restoration of the structure and the prevention of its collapse. Technical details of the wall: length ~1,400 m; maximum height ~12 m; thickness on average 70 cm at the base, reducing to ~40 cm at the top; material: natural stone bound with old lime mortar, with some areas historically reinforced with brick or dressed blocks. Technology used: photogrammetry with drones; sensor: high-resolution RGB camera (48 MP), providing detailed imagery for the 3D model; geographic positioning: PPK (Post-Processed Kinematics), an advanced technology for correcting the drone positioning data after the flight, which delivers very high precision; model resolution: 1 cm/pixel, allowing a very accurate analysis of cracks, erosion and deformation of the wall; number of processed images: ~4,400 aerial and terrestrial images combined to cover the whole wall through 360°. Purpose of the 3D modelling: historical documentation of the wall with verifiable digital data; structural analysis to identify the critical points at risk of collapse; continuous monitoring in order to compare deformations over time; restoration planning with minimal intervention, oriented towards authentic preservation.