A new method and working tool to interpret 3D ground‐penetrating radar data has been developed. Algorithms for feature extraction based on three‐dimensional regression techniques are developed to generate 3D models of the archaeological reflection features in the subsurface. After several attempts to reasonably visualize the information of a 3D ground‐penetrating radar (GPR) data cube by manual and automatic techniques, we propose a new approach: the visualization and interpretation steps are combined in an efficient and objective process in order to extract the geometrical information of the mapped archaeological features. Each object is modelled by six independent planes that form the structure that should be extracted. This is an appropriate approximation for walls, floors, stones as well as for pipes. To speed up calculation and because routines operating on the complete data set were not successful so far, the system utilizes a start line which is defined by the user. After 3D pre‐filtering with a sequence of median – dilation – erosion, followed by a 3D gradient filter, planes are matched to the borders of the anomaly by using a least‐median‐of‐squares algorithm. Finally, the found planes are refined by an analytical regression and the final box displayed in a 3D GIS software. The small computing time for a single object makes this method feasible for routine application of feature extraction from a 3D GPR data cube. The presented technique allows visualizing and extracting the imaged archaeological features rapidly and into an easy understandable representation.