Fraunhofer Institute of Optronics, System Technologies and Image Exploitation IOSB

3D Change Detection in Tunnels

3D Change Detection in Tunnels

In mining and tunneling, excavation and security alternate continuously. With a new method, the progress and quality of the tunneling can be captured in 3D and automatically evaluated. The method compares before and after scans and detects the changed parts accurately.


change detection on tunnel wall

When rocks are removed from the tunnel face, the forming cavities must be secured. The surface can be protected, for instance, by the application of shotcrete (known as New Austrian Tunneling Method). Depending on the layer thickness applied, the shotcrete protection is classified as poor, sufficient or too strong.


A new method for determining layer thickness allows an epoch-wise control of the concrete layer and thus leads to higher reliability and greater efficiency. Using a customary 3D laser scanner and the efficient methods of Fraunhofer IOSB, the laser scans taken at different moments of time can be easily compared.


The method is simple and fast, because

  • no markers need to be applied for scans,
  • scanner location can be arbitrarily chosen for each scan,
  • ongoing work in the tunnel is affected only for a few minutes during the scans.

The automatic comparison of before and after scans

  • detects  all areas that have been changed in between scans,
  • determines the amount of change, i.e. layer thickness,
  • matches the actual and planned layer thickness in order to point out too thick or too thin concrete layers.