1. A computer-implemented method for estimation and dynamic correction of absolute positions of stationary objects observed in a zone, the method comprising: insonificating the zone from different angles using a sonar detection system displaced above the zone; receiving data acquired by the sonar detection system; detecting acoustic shadows representing detected stationary objects projected on the zone based on the data acquired by the sonar detection system, each acoustic shadow being an observation; estimating the absolute positions of said observations in at least two dimensions; creating a fictitious object for each observation, each fictitious object being a contact; initializing an estimated position of each fictitious object based on the estimated absolute position of a corresponding observation; a first phase comprising: constructing a fictitious mesh based on the observations detected over time by representing each observation by a node having an initial position equal to the estimated absolute position of the observation, and by connecting the nodes together by fictitious elastic links; associating, when a new observation is detected, the new observation with a new node having an initial position equal to an estimated absolute position of the new observation, the new node being connected to a fictitious anchoring point in the zone by a first fictitious elastic link; integrating the new node into the fictitious mesh by new fictitious elastic links, each of the new fictitious elastic links connecting the new node to nodes of the fictitious mesh corresponding to observations preceding the new observation in time; and tying the new node associated with the new observation by another fictitious elastic link to a contact node associated with a contact corresponding to the new observation, an initial position of the contact node being the estimated absolute position of the new observation, such that the elastic links have initial lengths that do not exert tension on the nodes to which the elastic links are connected; a second phase comprising: fusing, when two observations of said detected observations relate to the same stationary object in the zone, the two observations by associating the two observations with a single contact, a position of the single contact being dependent on the estimated absolute positions of said two fused observations, the fusing of the two observations being at the level of the fictitious mesh by replacing contact nodes associated with the contacts initially corresponding to the two observations by a common contact node associated with a common contact, the common contact node being tied to the nodes associated with the two observations by way of the fictitious links initially connecting nodes associated with the two observations to the contact nodes associated with the contacts corresponding to the two observations; inducing tensions, based on the replacement with the common contact node into the fictitious mesh, on the nodes associated with the two fused observations, the tensions being transmitted to other nodes of the fictitious mesh by the fictitious elastic links; resolving the tensions by a modification of the positions of the nodes constituting the fictitious mesh; and replacing the estimated absolute position of the observation or the initial position of the contact associated with each node with the associated modified position of each node of the fictitious mesh, wherein the first phase is implemented throughout the duration of the zone analysis, and the second phase is implemented at each time a fusion of two observations is decided.