# Rebuild

Rebuild command tries to improve the qualities of NURBS data using fugen's logics. The target is NURBS curves, NURBS surfaces, and trimmed surfaces. Operators can specify what object is objective to improve by typing C(Curve), S(Surface:Non trimmed NURBS Surfaces), or F(Face:Trimmed Surfaces) keys. Typing one of the above keys limits selection target to each type of objects. Parameter Input Dialogue for the object appears when an object is selected.

The title of the dialogue shown indicates what kind of object is the target: Curve, Surface, or Face. The first line in the inner frame is the kind of curves, surfaces, or base surfaces of face: LBRep=Non Rational B-Spline CurveARLBRep=Rational B-Spline, and so on.

Tolerance:is the maximum deviation allowed for curves or surfaces.

Re-Parameterize Frame

- Non-Reparameterize: Does not change the parameter range.

- [0,1] Reparameterize: Changes the parameter range to [0,1].

- Chord Length Reparameterize: Updates the parameter range to chord length sum of each knot span.

- Specify Range: Operator input the parameter range from KB

Chord Length Parameterize is recommended. Mathematically, this is the best parameter range since the magnitude of first derivative is nearly equal to one.

Non-Rationalize:When the target object is a rational B-Spline, this option is effective, Specifies to convert to Non Rational B-Spline.

C1-continuous Edge Join:When the target object is a Face(Trimmed Surface), this option is effective, Specifies to remove vertices of C1 cotinuous(more precisely G1 continuous) edges. Fugen converts the two edges to one, by connecting the two curves to one.

Even if C1-continuous Edge Join not specified, Fugen removes unnecessary knot multiplicities of NURBS curves. One example of the improvement is tangent vector magnitude adjustment. Rebuild of trimmed surfaces reparameterizes the edge's parameter range to make the tangent vector length at vertices as equal as possible.

TIPS: To recognize how edges' vertices are removed, use Analysis:Edge Show before rebuild.

(Note)Rebuild of surfaces changes the order of the surfaces to 4(degree 3).