Feature plays an important role in reverse CAD modeling. Based on the multiresolution modeling

a series of approximation models and algorithms for feature curves extraction from the triangular Bézier patch is studied. First

a near coplanar merging algorithm based on Gauss sphere is used to generate superfaces. Then the outer and inner boundaries of every superfaces are extracted

which are original or coarse feature curves. Taking account of the complexity and arbitrary of triangular Bézier patches model

editing operation applying on feature curve is inevitable during practical application. The feature curves are the important reference fo rectangular boundaries definition. This research has laid a good fundamental for fulfilling the local B-spline surface reconstruction from triangular Bézier patches. Some experimental results show that the above method is feasible and satisfying

and reasonable rectangular topological B-spline surfaces can be reconstructed according to the feature curves extracted from the triangular Bézier patches.