An imaging system as disclosed can include multiple bistatic radar sensors configured to transmit electromagnetic waves towards a surface of a target object and configured to measure the electromagnetic waves reflected from the surface of the target object. The imaging system includes a computing device that determines time of flight estimates based on the measured waves. The computing device can draw, within an image model for the target object, multiple candidate surface portions of the surface of the target object based on the TOF estimates and predetermined positions of the bistatic radar sensors. Further, the computing device can assign weights to the candidate surface portions. The computing device can determine points where the candidate surface portions meet with a predetermined probability based on the weights. The computing device is configured to define an estimated surface of the target object in the image model based on the determined points.