Special Models for Animation - Computer Animation: Algorithms and Techniques - page 382

FIGURE 12.22
Sequence of subdivision steps.

(a) (b)

FIGURE 12.23
During subdivision, each vertex is replaced by a face. (a) Original vertex of object to be subdivided. (b) A face
replaces the vertex by using new vertices defined on connecting edges.

FIGURE 12.24
During subdivision, each face is replaced by a face using the newly defined vertices on its edges. Original face of
object to be subdivided.

V A and V B are the other vertices of the faces that share the edge. Each original vertex is repositioned by
a weighted average of its original position and those of all the vertices connected to it by a single edge.
There have been many schemes proposed for repositioning the original vertices. A particularly simple

sÞV þ s X

n

one is V¼ð W i where V is the original vertex position and the nW i s are the connected

1

i ¼ 1

3

vertices, s ¼

4 n .