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. Author manuscript; available in PMC: 2010 Oct 1.
Published in final edited form as: IEEE Trans Nucl Sci. 2009 Oct 1;56(5):2728–2738. doi: 10.1109/TNS.2009.2016196

Fig. 7.

Fig. 7

Fitting of a v knot line of the 2D NURBS surface to a tag line. A NURBS curve (grey) approximates the tag line. Each grid point along the knot line needs to be repositioned to corresponding points on the NURBS curve. The new position for each grid point is found by intersecting the NURBS curve with the u knot of the grid point. For example, the grid point Pgrid (circle) needs to be moved to the new location P̂grid on the tag curve. The grid point is moved by altering the location of the corresponding surface control point Pi,j (square). The control point is initially located at the same location of the grid point (intersection of the knots). Movement of the control point does not correspond one to one with the movement of the grid point, however. In the above example, the control point Pi,j must be moved a greater distance in order to set the grid point in the desired location. Control points are manipulated in this manner for all grid points of the v knot line to fit it to the tag curve.