1. A method for locating difficult access points on a topological map using discontinuities between curvilinear distances of neighboring points, the method comprises the steps of: scanning points on a map of curvilinear distances, using reliefs only crossable by detour trajectories; reading estimated value DT( 0 ) of the curvilinear distance assigned, in the map of curvilinear distances, to a point C 00 under analysis; determining a Euclidean distance C(V) separating a point V under investigation, from the point C 00 under analysis using a chamfer mask distance transform; determining an estimated value DT(V) of the curvilinear distance assigned, in the map of curvilinear distances, to the point V under investigation; calculating an absolute value of any discrepancy between the estimated values of the curvilinear distances, DT( 0 ) and DT(V), with the determined Euclidean distance C(V); determining a difficulty of access of the point C 00 under analysis based upon an inequality of the absolute value calculated and the determined Euclidean distance C(V); and rendering a display of a map indicating difficult access points.