18. The system of claim 17 , wherein the feature determination unit comprises a size determination module having an input and an output for determining the junction size, the input of the size determination module coupled to the output of the location determination module to receive the junction location, the output of the size determination module coupled to the input of the descriptor creation unit.
19. The system of claim 18 , wherein the feature determination unit comprises an orientation determination module having an input and an output for determining a junction orientation, the input of the orientation determination module coupled to the output of the size determination module to receive the junction size, the output of the orientation determination module coupled to the input of the descriptor creation unit.