Ship hull surface′s NURBS representation and design

Using the object oriented technique, authors define the customer classes for ship hull form modeling in the ObjectARX programming environment. Through DAO database API of MFC, the connection between AutoCAD and outside database (MS Access, MS SQL Server etc.) is established. According to the points net of offset, authors give the boundary conditions, interpolate the ship hull shape with NURBS surface, and represent the ship hull form. At last, an algorithm for surface plane intersection based on projection principle is proposed. Firstly isoparametric curves are divided into line segments respectively. Then a new auxiliary space, i.e. projection coordinate system, is established. Projecting intersections between plane and line segments in auxiliary space, mapping intersections form auxiliary space into object space, intersections between NURBS surface patches and an arbitrary plane are implemented finally.