Study on eliminating methods of projection length distortion in high mountain areas

The paper studies the two main factors for the projection length distortion, presents the solving methods of eliminating projection length distortion value in high mountain areas when the projection length distortion value is bigger than 2.5cm/km. Including concentric reference ellipsoid method, map projection zone transformation method and compensating projection plane method. Engineering practice shows that the methods can effectively eliminate the errors brought by the projection length distortion.