We add a null label on the map to model the missing cartographic data.
This label is located within a constant distance d, w.r.t. all the nodes.
The potentials w.r.t. order 2 cliques yield homogeneity
constraints:






The potentials w.r.t. order 1 cliques represent the data attachment term:
Distance between the pixel and the label (cartographic segment)
The energy defined by the sum over all the potentials
is minimised using simulated annealing with a Metropolis dynamics.