Many people tend to use trim edges to create surfaces. However, by using so the resultant surfaces may become heavy or may contain multi-knots. The Curve Edit > Fit Curve function can be used to create quality curves. But the fit curve (till v 2010) function only operates on cross-section data.

Object edit > Align 2008 function can be used to fit quality curves through any surface edges, including trim edges. The following are the steps involved
Create a line ( degree 1 curve) near the edge we want to fit.

Deselect all geometry before invoking Object edit > Align 2008.

Select second object as the object to change and choose explicit control. Select the edge first and the curve after that .The end points of the curve is snapped to the end of the edge.

Exit from the function and the raise the degree of the curve, till we get a satisfactory fit.

Additional diagnostic functions such as curvature comb and curve to surface deviation should be used alongside to check for quality and deviation.

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