This is a part of my Capstone Research. 

Using the imaginary part of voltage of nodes in branch, turning points of a tortuous branch can be identified.

Using derivation of argument part of voltage, and choosing points in peaks of nodes, possible turning points can be chosen.

Example of tortuous branch with three main turning points

Bottom left graph is the derivation of imaginary part of voltage. Three blue circles indicate the index of three turning points.

Another feature point is the sudden change of radius in a branch. Use the second order deviation of real part of voltage, the sudden changing point can be determined.

Example of sudden decrease of radius in a branch

The blue circle in bottom right graph shows the shrinking point in this branch.

There is not always feature points in a branch. Actually, many small branches do not have any kind of feature point. In addition, the detection of these points are not always correct, so there is a high chance that the feature points can not be paired in the matching branch. But the detection of feature points is not compulsory. With these feature points in a branch, branches can be further separated into several sub-branches, so that the pairing accuracy can be enhanced.