5 Conclusion
In this paper we present the state of the art in hair simulation, one of the most challenging problem of virtual humans. We consider three aspects in hair simulation: hair shape modeling, hair rendering and hair dynamics. Different approaches have been proposed in the literature dealing with one or more aspects of hair simulation. We divide them into four categories based on the underlying technique: particle systems, volumetric textures, explicit hair models and cluster hair model. Some of these techniques are appropriate and effective only for one of the aspects in hair simulation. In figure 14, we summarize their role with their effectiveness and limitations for each aspect of the hair simulation. Notice that we have introduced a new hair modeling paradigm - “Hair as a Fluid”. We believe, this approach has good potential
in terms of hair shape modeling and hair dynamics, as the methodology gives a basis for modeling complex hair-hair interactions.
No, doubt research in hair simulation despite the inherent difficulty of its size has been encouraging and shown remarkable improvements over the years. People in general are not ready to accept a bald digital actor or an animal without fur.Such realism to computer graphics characters is also becoming more widely available to the animators. Many of the commercial software provide suitable solutions and plug ins for creating hairy and furry characters. An article by Robertson [21] gives an overview of various techniques available for animators.

However, the quest of realism increases after noticing what one can already achieve. This asks to continue our research for better solutions. Hair dynamics for instance remains an area, where existing computing resources impose constraints. It is still very far to imagine real time hair blowing with full rendering and collisions. Hair dressing and styling also require flexible and convenient modeling paradigms. Fast and effective rendering methods for all hair styles -short or long, in all conditions -dry or wet, modeling all the optical properties of hair are still to be explored. So there is still long way to go