“…InSAR scatterers are typically not situated at ideal locations, and the observations have an imaging geometry that is not optimal for retrieving full three-dimensional (3D) displacements. Moreover, they are only sensitive to the projection of the 3D displacement vector onto the radar line-of-sight (LoS) direction, d LoS , along a plane orthogonal to the LoS (Massonnet and Feigl, 1998;Fialko et al, 2002;Hanssen, 2001;Wright et al, 2004;Brouwer and Hanssen, 2023b), i.e., T is the 3D displacement vector in east, north, and up direction, respectively. 1 P LoS ⊥ is the orthogonal projec-tor onto the LoS, where θ is the incidence angle towards the radar, and α d is the azimuth of its zero-Doppler plane (ZDP) at the position of the target, in the direction towards the satellite, see Brouwer and Hanssen (2023b, Fig.…”