Method for estimating the dimensions of an object from points acquired by a lidar sensor

A method for estimating at least one dimension belonging to a reflective surface of an object, the method being implemented by a device comprising at least one lidar sensor, computer and memory, the memory storing a model of the object comprising a first dimension and a second dimension of the reflective surface of the object and a reflectivity of the reflective surface of the object, the method comprising:

• the lidar sensor acquiring a set of points, each point being associated with three-dimensional coordinates in space and with an intensity value;
• selecting, from the set of points, a group of points which are presumed to belong to the same object;
• estimating, from the three-dimensional coordinates of the points in the group of points, values of a first and of a second dimension of the object corresponding to the first and to the second dimension, respectively, of the reflective surface of the model of the object;
• estimating, from the intensity values of the group of points which are presumed to belong to the object, a reflectivity value for the object corresponding to the reflectivity of the reflective surface of the model of the object;
• then
• for at least one specific point in the group of points which are presumed to belong to the object:
• estimating a cross section of a specific light beam, the reflection of which by the reflective surface of the object made it possible to obtain the specific point, from the estimated dimensions of the reflective surface of the object and from a divergence of the light beam determined from a distance between the specific point and the lidar sensor;
• estimating a theoretical intensity value received by the lidar sensor after the specific light beam is emitted, from the estimated cross section of the specific light beam and from the estimated reflectivity value for the reflective surface;
• determining an intensity error associated with the specific point from a difference between the estimated theoretical intensity value and the measured intensity value which is associated with the specific point after the specific light beam is emitted;
• and
• correcting the estimate of the value of the first dimension on the basis of the intensity error associated with at least one specific point.