1. A method for establishing a frontier between a first object and at least a second object in a depth map associated with a scene according to a point of view, wherein the scene comprising the first object and the at least a second object, at least a part of the first object and at least a part of the at least a second object being visible from the point of view associated with the depth map through a set of elements of the depth map, the first object and the at least a second object being modelled with surface elements, the method comprising: from depth information associated with a point of the scene visible through a first element of said set of elements of the depth map from depth information associated with said first element and from depth information associated with the other elements, called second elements, of said set of elements, establishing a line associated with a direction associated with the frontier between the first object and the at least a second object, establishing said frontier between the first object and the at least a second object according to information representative of distances between said line and a part of vertices of the surface elements visible through said set of elements selected according to the orientation of normal associated with said vertices.