Ricoh Company, Ltd.

Hiroaki Chiyokura

Kouichi Konno

A free-form surface generating method. There is a generating of a continuity condition by detecting a continuity on a common boundary of two free-form surfaces based on tangent vectors on a NURBS common boundary curve and tangent vectors on boundary curves continuous to end points of the NURBS common boundary curve. Next, one of a plurality of predetermined joining processes is selected in accordance with the continuity condition. Then, internal control points of each of the two free-form surfaces are generated based on the selected joined with continuity on the common boundary are generated.

Free-form surface generation from detected geometric continuity on

A method of generating a free-form surface includes calculating cross boundary derivatives on all the boundary curves forming a face, and storing the results in a memory device (STEP 1), determining whether the cross boundary derivatives calculated at STEP 1 are all polynomials or not, and if there is a rational function, go to STEP 3, if they are all polynomials, go to STEP 4 (STEP 2), creating the control points of a rational surface by using the cross boundary derivatives (STEP 3), and creating the control points of a polynomial surface by using the cross boundary derivatives (STEP 4).

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Tokyo, Japan

Hiroaki Chiyokura