The conditions for G1 continuity between two adjacent bicubic B-spline surfaces with double interior knots along their common boundary curve are obtained in this paper, which are directly represented by the control points of the two B-spline surfaces. As stated by Shi Xi-quan and Zhao Yan, a local scheme of constructing G1 continuous B-spline surface models with single interior knots does not exist; we may achieve a local scheme of (true) G1 continuity over an arbitrary B-spline surface network using these conditions.
Some practical problems in designing the outline of hidden airplane require to construct high-order surfaces with at least second order continuity. The high-order smooth surfaces'construction has been always a difficuit problem in CAGD. In this paper, G^2 smoothness between two biquintic surface patches is discussed, and the intrinsic conditions of the control vectors of the common boundary curve are presented.
