Continuity between Gregory-like patches Original Research Article

The Gregory technique seeks to construct patches on the faces formed by a net of intersecting curves in space. It uses the curves themselves and cross-boundary tangent information, and the resultant patches join together with tangent plane continuity. Extensions of the technique to give second-order continuity are investigated. It is shown that a direct generalisation fails because local coordinate systems do not interact appropriately. An alternative means for generating these coordinates is proposed. This works successfully for patches with at least four sides and gives curvature continuity across patch boundaries.