Abstract: The invention is directed toward a method and apparatus for generating hollow and non-hollow solid representations of an object represented in terms of volumetric data. The volumetric data represents the object in terms of a plurality of voxels, each voxel having a plurality of voxel faces that interconnect to enclose a voxel volume that represents a portion of the object volume or a portion of the volume of a background substance. A surface representation is generated that represents the object with a plurality of surface voxel faces defining a surface that encloses the voxels whose volumes represent the object volume. An array of control points is formed from the surface representation, each control point corresponding to a surface voxel face. A NURB based solid representation of the object is generated from the array of control points. The NURB based solid representation can be used to drive a CAD/CAM system to generate a replica of the object or can be used for various other purposes.