Based on the residue theorem of Interferometric SAR

in depth analysis and detailed description of Branch Cut algorithm

one of the most popular In SAR phase unwrapping approaches

has been given in this paper.Many wrong implementations and premature conclusions about Branch Cut method caused by the over brief description of Goldstein's orig inal algorithm and not enough understanding of the residue phenomenon have been clarified and rectified totally.Besides

grounding process and dipole remover preprocessor are introduced in Goldstein's Branch Cut algorithm to get tremendously length reduced branch cuts and more continuous unwrapped phase surface.Finally

the performance and character of Branch Cut method are discussed and branch cut is stated as an essential factor for all the phase unwrapping approaches

either existed or under developed

for its nature of isolating the residue effect.X-SAR data based experimental results are presented as the proof of the paper.