Interferometric Synthetic Aperture Radar (InSAR) is a remote sensing and geodetic technique for ground deformation measurements using radar images of the Earth's surface that are collected regularly by orbiting satellites equipped with SAR sensors. Natural reflectors on the ground which backscatter the radar signal to the satellite are monitored in different time and changes of the line of sight (LOS) distances can detect ground surface movements. Natural reflectors are abundant in many places specially in urban areas. However, areas that are densely vegetated or covered by snow have limitations for InSAR technique and therefore artificial corner reflectors, passive or active ones, can be used instead. These corner reflectors are devices which provide precise measurement points and can be installed at desired locations. These devices can measure temporal LOS changes of the measurement point precisely using InSAR technique.

Since 2020, Lantmäteriet has installed three active electronic corner reflectors (ECR) and several types of passive reflectors (CR) in different locations of Sweden. The plan is to continue and complement the national geodetic infrastructure with at least 20 passive reflectors which are collocated with permanent GNSS stations and/or tide gauges. Among others, these colocated permanent GNSS stations and corner reflectors can potentially contribute to the development and validation of the national and European ground motion services. Moreover, the colocation helps to map the relative ground motions estimated with InSAR to an absolute geodetic refercne frame.