The direction may be changed at every point of the face, depending on the curvature of the face. They are determined as follows. If the surface normal is the same as the direction, a warning message will appear.

Figure 10.47: Tangential Direction

: User defined welding point

, : Nearest points on the surface from point.

: Normal direction (Unit vector)

: Orthogonal Tangential direction (Unit vector)

: Real Tangential direction (Unit vector)

: User defined Tangential direction (Not unit vector)

: Unit vector of user defined Tangential direction

= , =

= ,=