Summary: As the finite element method is widely used in strength analysis, automatic mesh generation draws more attention these days. For a given geometric tolerance value, the purpose of mesh generators is to discretize the continuous model within this error limit. Faithfulness to this condition produces many small elements at small features. Often, these regions are of little interest and computer resources are thus wasted. It is wished to suppress selectively, small features from the model before discretizing. This can be achieved by low-pass filtering a CAD model. A method to apply the techniques in signal processing to the manipulation of a three-dimensional model is proposed.