G1 Bezier Surface Generation from Given Boundary Curve Network with T-Junction

T-junctions usually appear in surface modeling processes that start with a given curve net work. However, since T-shaped patches are not available in current CAD system so existing G(1) surface generation methods are restricted to n-sided patches. Therefore a designer must design a curve network with T-junctions, or subdivide it, into n-sided patches, to avoid T-shaped topologies. We generate G(1) Bezier surfaces at a T-junction by combining the coplanar G(1) continuity condition with the de Casteljau algorithm to avoid the collision of twist points. Both T-junctions in the middle of boundary curves and at 3-valent vertices are considered. Our method requires no subdivision or triangulation of the surface, and the curve network is not changed.