A not crossable element (NCE) is marked using a shape on a map. A map data does not prevent a route from crossing the NCE. A closed area is selected on the map, which includes a polygon bound on one side by a portion of the shape. A set of mapping points (MP) that are included in the closed area is selected. A route is formed by connecting one MP to another MP. A subset of MPs is identified as a set of candidate MPs (CMP). Each CMP lies within a search distance of a not-mapping point (NMP). The CMPs are sorted according to CMP-NMP distances. A subset of CMPs is selected whose paths to the NMP do not intersect with any shape corresponding to any NCE in the closed area. The NMP is linked in the route with a selected CMP from the subset of CMPs.