Building Differential Deformation (BDD)

The PSI technique can be used to monitor deformations over very wide areas. An example is given by the European coverage achieved by the European Ground Motion Service (EGMS). Starting from the EGMS datasets, GeoKinesia and the CTTC (Centre Tecnològic de Telecomunicacions de Catalunya) have proposed an analysis of the spatial differential deformations (spatial gradient of deformation), which are directly related to damages to structures and infrastructures. In fact, the most significant damages are often associated with high spatial differential deformations, i.e. high spatial deformation gradient values.

The procedure, which is called Building Differential Deformation (BDD), requires as inputs the EGMS Basic product and a vector map of buildings and infrastructures. The procedure was firstly described in Shahbazi, Crosetto and Barra (2022): “Ground deformation analysis using basic products of the Copernicus ground motion service”, International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 43, 349-354.

For all buildings covered by enough measurement points, the algorithm computes the slope (gradient) and aspect of the deformation field, highlighting the local maximum deformation slopes. The BDD can be a useful screening tool to analyse large PSI datasets. The reliability of the procedure depends on the number of measurement points falling inside a given building.

An example of BDD output is shown in the figure below, which illustrates several buildings in the study area characterized by low to high gradient intensity.

The BDD procedure has been used to assess the potential building damage map of Spain, available at https://groundmotionADAs.com.

This map identifies hundreds of buildings affected by low to high gradient intensity.