14
LFF Algorithm
          Let G be the set of detected image features.
          Let Fm be focus features of the model.
          Let S(f) be the nearby features for feature f.
        for each focus feature Fm
          for each image feature Gi of the same type as Fm
    1. find the maximal subgraph Sm of S(Fm) that matches a subgraph Si of S(Gi).
    2.  Compute transformation T that maps the points
        of each feature of Sm to the corresponding one of Si.
    3.  Apply T to the line segments of the model.
    4.  If enough transformed segments find evidence in the image, return(T)