A method for producing map images of current velocity vectors at the surface sea is described in which beams of electromagnetic waves are emitted towards the surface using a system, towards the left forward and right forward sides of the track of the system, and towards the left aft and right aft sides of the track, from two antennas at a distance from each other along the direction of the track and along a direction perpendicular to the track, and values of roll angle and length of the antenna base connecting the two antennas are determined using differential interferometries applied to the electromagnetic waves reflected by the surface between beams emitted forwards and backwards, the map images being built up using an along-track type differential interferometry, using roll angle and antenna base length values obtained.