freeform-based form feature modeling using a hierarchical & multi-resolution nurbs method
In a three dimensional (3D) environment, non-uniform rational B-spline surfaces (NURBS) have been a standard in CAD industry for free-form shape modelling. Feature based design is widely used in CAD design. This paper addresses the issue of form feature design on free-form surfaces. Based on the multi-resolution and refinement scheme, the Hierarchical NURBS (H-NURBS) representation is proposed for localized form feature modelling. More specifically, the patch-based form feature modelling concept will be discussed. H-NURBS representation introduced here not only offers powerful functionality for form feature modeling on freeform surface, but also overcomes the problems inherited from the traditional control point based shape modelling. We will investigate first the extrusion operation to create various form features on freeform surfaces. Patterning operation of form features as well as form feature cut-&-paste operation on freeform surfaces/shapes will be studied for efficient and effective local shape design. Interactive methodology and techniques will be developed for the patch-based form feature modelling with an emphasis on the native and easy parameter control.
form features nurbs hierarchy shape modification