The present invention relates to a method and an arrangement for providing a 3D model of an environment. The method comprises the step of forming a mesh modelling the environment in three dimensions, said mesh comprising nodes interconnected by edges and having surfaces boarded by the edges, wherein each node is associated to a 3D coordinate in a geographical coordinate system, determining for a plurality of the nodes and/or surfaces and/or edges in the mesh a mesh uncertainty and associating the determined mesh uncertainty to the corresponding node and/or surface and/or edge.