You can fit surfaces to facet bodies, curve features or groups (point sets or point groups) as part of a reverse engineering workflow with the NX Fit Surfaces command in NX 9.
Tod Parella shows you how to take advantage of the Fit Surfaces command in NX in this NX Quick Tips video.
You can fit five types of surfaces.
You can control the degree and number of patches, patch uniformity and fit direction. You can also control the boundary definition and smoothness of the fitted surface.
You can specify a direction constraint for a planar surface so that the plane normal is parallel to the specified direction.
You can specify a radius value constraint for a spherical surface.
You can create an open or closed spherical surface.
You can specify a radius value constraint for the cylindrical surface. If you apply a direction constraint, it is applied to the center line of the cylinder.
You can create an open or closed cylindrical surface.
You can specify an angular constraint for a conical surface. When you have an angular constraint, the half angle is fixed to the value you specify.
If you apply a direction constraint, it is applied to the center line of the cone.
You can create an open or closed conical surface.
For more details, check the NX 9 Help documentation.