초록 ▼

Beginning with a CAD specification of an object, the method and apparatus of the invention reduces the overall time to produce a shell of the object with a rapid prototyping machine. The reduction in time is achieved by interleaving the computation and the building tasks and by not requiring an expl

Beginning with a CAD specification of an object, the method and apparatus of the invention reduces the overall time to produce a shell of the object with a rapid prototyping machine. The reduction in time is achieved by interleaving the computation and the building tasks and by not requiring an explicit evaluation of a shell of the solid at the outset. The method is shown to operate with STL data, or with other CAD data, directly, and can also be employed to create non-planar objects, such as models of sheet metal parts that are represented only as surfaces. Furthermore, the method can be employed to produce a smooth outer surface even when employing polyhedral approximations to the surfaces of the object.

대표청구항 ▼

A method for operating a system to fabricate a three dimensional object from a computer-generated specification of a solid S, the computer-generated specification of the solid S being oriented in an xyz-coordinate frame and having a height along the z-axis, comprising the steps of: (a) preprocessing

A method for operating a system to fabricate a three dimensional object from a computer-generated specification of a solid S, the computer-generated specification of the solid S being oriented in an xyz-coordinate frame and having a height along the z-axis, comprising the steps of: (a) preprocessing the computer-generated specification of S, the step of preprocessing including the steps of, for each face fi lying on a boundary of the solid S, constructing a bounding z-axis interval Ii=[zimin, Zmax]; for all i, constructing an enlarged interval Ii+=[zimin-t, zimax+t], where t is a thickness of a shell of S; and storing the enlarged intervals I+for subsequent access; (b) searching the stored enlarged intervals to determine a specification of one slice of the shell of S, including the steps of, initializing a set of primitive slices =NULL; and for each interval Ii+that contains a query point zq that overlaps with a query interval Iq, adding P�i�Bt)}to H, where P is a slice plane, c1 indicates a closure, and Bt is an open ball of radius t; (c) merging the set of primitive slices by performing a union of all of the primitive slices in to obtain S��S