Abstract: A method for determining the velocity of a moving fluid surface, which comprises the following steps S1 to S5: S1) taking a sequence of images of the moving fluid surface by at least one camera; S2) comparing a first image from the sequence with a second image from the sequence in order to distinguish moving patterns of the fluid surface from non-moving parts and to obtain a first processed image (im_1f) comprising the moving patterns; S3) comparing a third image from the sequence with a fourth image from the sequence in order to distinguish moving patterns of the fluid surface from non-moving parts and to obtain a second processed image (im_2f) comprising the moving patterns; S4) comparing the first and second processed images in order to determine the spatial displacements of the moving patterns; and S5) determining from the spatial displacements the velocity.