Surface velocities of ice-sheets are of major interest in ice-sheet modelling and overall questions addressing mass balance studies. Since on-site measurements are sparse, the large scale derivation of surface velocities relies on satellite imagery.

Depending on the area of interest, different techniques and sensors may be  used. If the scene has enough contrast, prominent features can be tracked over varying time intervals in both optical and radar images. In order to get a higher spatial resolution, the radar images are focused using amplitude and phase of the backscattered signals.. The resulting SAR images can be used in an interferometric approach (InSAR), in which mutliple scenes are evaluated with respect to phase differences. These phase differences can be linked to the local topography and ice flow.