NURBS streams

Deformable objects are important in modeling clothing, facial expression, animal characters and other soft-objects. However, they are rarely used in distributed virtual environments. It is because both the transmission and the tessellation of deformable objects are too time consuming to run in real-time. Part of the problem can be solved by our earlier method on real-time rendering of deformable NURBS surfaces. In this paper, we present a technique to organize the data structures used to store the pre-computed polygon models and the deformation coefficients in supporting the rendering of deformable NURBS surfaces from hierarchical form into a linear form, called NURBS streams. The NURBS streams will not only support progressive transmission and rendering of deformable NURBS surfaces, but also simplify software and hardware implementation of the rendering method. To further speed up the rendering of these NURBS streams, we also introduce the idea of virtual rendering list to keep track of incremental node changes between successive frames.