The invention relates to encoded surfaces that are read by a three-dimensional radar imaging system. The reader scans different zones in a pre-determined area of the encoded surface, each of said zones comprising projections or indentations, similar to Braille. The image obtained can be used to estimate the position of the camera relative to the known pattern. The relative movement between the reader and the encoded surface allows other areas of the surface to be scanned and, in this way, the sensor can decode a message etched along the path followed by the imaging sensor.