The three geodetic techniques InSAR, levelling and GNSS are complementary w.r.t. (i) the sensitivity to horizontal and vertical displacement components, (ii) the spatial and temporal resolution of the measurements and (iii) the accuracy of the resulting displacements. We present a strategy to robustly combine the displacement estimates of the three techniques with a focus on long-term, linear movements. The linear displacement rates from InSAR in ascending and descending image geometry are combined with vertical and horizontal rates from levelling and GNSS, respectively, resulting in 3D velocity vectors at a dense surface grid. The results of our combination approach indicate that it is possible to derive realistic surface movements on the sub-mm/a scale with significance.@en