1. A method for determining a triplet of parameters defining a ground plane in a three-dimensional reference frame on a basis of a depth image obtained from a sequence of images, the method comprising: selecting valid points from a current depth image, the valid points being points of the current depth image whose distance from a point of origin of the three-dimensional frame of reference is in a range between a predetermined minimum distance and a predetermined maximum distance, determining a first indicator R 3d for the current depth image, said first indicator being dependent on a number of valid points in the current depth image, and on a total number of points in the current depth image, selecting a set of points of interest in the current depth image, each point of interest being selected if a distance between said point of interest and the ground plane determined for a previous image in the sequence of images is below a first threshold d sel , determining a triplet of spatially filtered parameters on a basis of the points of interest, and determining a triplet of temporally filtered parameters as a function of the first indicator R 3d determined for the current depth image, for the previous image, or for another a previous image in the sequence of images.