A method for estimating the motion of a carrier with respect to an environment in relation to which said carrier is moving, the carrier incorporating at least one navigation sensor and at least one vision sensor producing images of the environment, said method including steps of: - identifying, in images acquired by the vision sensor, characteristic elements of the images representing characteristic elements of the environment, - calculating at least one condensed measurement based on characteristic elements of at least two images acquired at different times, the at least one condensed measurement being representative of features of the motion of the carrier during the acquisition of said at least two images, the at least one condensed measurement being representative: o of a ratio of the distances travelled by the carrier between the times of acquisition of two pairs of images of a triplet of images, based on characteristic elements of the images of said triplet representing characteristic elements of the environment visible on each of the three images of said triplet, and/or o of a direction of displacement of the carrier and/or a rotation of the carrier between the times of acquisition of a pair of images, based on characteristic elements of this pair of images representing characteristic elements of the environment visible on each of the two images of this pair, - estimating the motion of the carrier by an estimate filter, called a "navigation filter", based on navigation measurements carried out by the navigation sensor and based on the at least one condensed measurement, characterised in that the at least one condensed measurement is calculated based also on an a priori estimate of the motion of the carrier provided by the navigation filter. - identifying, in images acquired by the vision sensor, characteristic elements of the images representing characteristic elements of the environment, - calculating at least one condensed measurement based on characteristic elements of at least two images acquired at different times, the at least one condensed measurement being representative of features of the motion of the carrier during the acquisition of said at least two images, the at least one condensed measurement being representative: o of a ratio of the distances travelled by the carrier between the times of acquisition of two pairs of images of a triplet of images, based on characteristic elements of the images of said triplet representing characteristic elements of the environment visible on each of the three images of said triplet, and/or o of a direction of displacement of the carrier and/or a rotation of the carrier between the times of acquisition of a pair of images, based on characteristic elements of this pair of images representing characteristic elements of the environment visible on each of the two images of this pair, o of a ratio of the distances travelled by the carrier between the times of acquisition of two pairs of images of a triplet of images, based on characteristic elements of the images of said triplet representing characteristic elements of the environment visible on each of the three images of said triplet, and/or o of a direction of displacement of the carrier and/or a rotation of the carrier between the times of acquisition of a pair of images, based on characteristic elements of this pair of images representing characteristic elements of the environment visible on each of the two images of this pair, - estimating the motion of the carrier by an estimate filter, called a "navigation filter", based on navigation measurements carried out by the navigation sensor and based on the at least one condensed measurement, characterised in that the at least one condensed measurement is calculated based also on an a priori estimate of the motion of the carrier provided by the navigation filter. <EOS>