Efficient Handling of Deformable Surfaces


Deformable objects may be needed in many computer graphics and virtual reality applications. They are particularly useful in modeling clothes, facial expression, human and animal characters. A common method to render these objects is by tessellation. However, the tessellation process is computationally very expensive. As an object is deforming, we need to retessellate the surfaces in every frame. This computational burden poses a significant challenge to the real-time rendering of deformable objects. Consequently, deformable objects are seldom supported in existing virtual reality systems.

In this project, we are developing techniques to support real-time rendering of deformable objects. Our earlier work focused on objects represented by NURBS surfaces and we have developed a very efficient method for rendering deforming NURBS surfaces. The basic idea of our method is that we maintain two data structures of the deforming surface, the surface model and a polygon model representing the surface model. As the surface deforms, the polygon model is not regenerated through polygonization. Instead, it is incrementally updated to represent the deforming surface. Two techniques are fundamental to our method: incremental polygon updating and resolution refinement.

This NURBS rendering method has been extended to cover most of the parametric surfaces.

Click here for a gzip'ed demo video (5MB in size) of interactive editing a human face model.

An efficient method for detecting inter-collisions as well as self-collisions of deforming NURBS surfaces has also been developed.

Click here for a demo video (3.7MB in size) on detecting inter-collisions of two NURBS surfaces.

Click here for a demo video (3.2MB in size) on detecting self-collisions of a NURBS surface.

Recently, we have extended the NURBS rendering method for efficient rendering of trimmed NURBS surfaces.

Click here for a demo video (5.3MB in size) on trimming and deformation of a teapot model.

Click here for a demo video (6.6MB in size) on deformation of a trimmed head model.


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Last updated on 21st August, 2003.