Input: , the dip angle set corresponding to M, and the threshold angle 
Output: The classification result set E of branch edges’ points 
Initialize: Set the set E = NULL 
Main steps of algorithm: 
Define a matrix H and initialize H = null; and then compute all the elements of the matrix 
according to the equation 

Calculate the position of the maximal value of H; assuming the maximum is at (), set = null, 
and , and then, compute the classification center 

Update , and by all angles that satisfy the condition ) searched 
from the set ; 
Repeat step until the angle set that satisfies the condition never change and place 
the junction points corresponding to the angle set into E; 
Repeat steps , and until all the elements of H are null, and then return E. 