In the area of computer graphics and virtual reality computer generated virtual humans have a prime importance. They are used in many computer graphics and its related areas in applications such as virtual worlds, digital archiving and gaming. Even though methods exist for creating extremely convincing humans, faces and their related animations, modeling hair in its naturalistic beauty and behavior still remain a challenge.This complexity of hair causes it to be hidden in most applications with hats or by other means or it is just simplified to be polygons which diminish its naturalism, even though hair is an important cue of individual recognition. Complexity of hair simulation arises not from an individual hair itself it comes when these individual hairs are considered as a whole in a human head. So at present when considering modeling, styling, simulating and animating realistic looking hair on virtual humans it remains a slow tedious process.
What is Hair and Hair Simulation?
A typical scalp of hair has about 100,000 to 150,000 hairs and in geometry hair is a thin curved cylinder having varying thickness. Each strand of hair can have any degree of waviness form straight to curly and the colors ranging form black to gray due to pigmentation and shininess. Due to the factors such as geometric intricacies of a hair, light and shadow interaction among hair, small scale thickness of individual hair compared to the rendered image, hair to hair and hair-body collisions hair simulation can be dissected in three major parts known as hair modeling, hair dynamics and hair rendering. Even though these processes can be taken into focus independently in real simulation environment these process are interleaved while processing hairs. Hair shape modeling phase deals with the overall geometry of the hair. It does this by creating thousands of individual hair and then altering the overall geometry of the scalp by using density, hair distribution, individual and overall orientation of hairs and complex hair-hair interactions and hair-body interactions. Once this phase is complete the geometry created by this phase is used by the other two phases to produce the final output. The hair dynamics phase addresses the movements of individual hair stands their collisions with other objects as well as with each other. In the field of virtual humans, hair possesses one of the most challenging rendering problems in computer graphics. The difficulties arise in hair rendering due to the amounts of hair, detail of geometry of an individual strand, complex light and shadow among the hairs and their small thickness when compared to the rendered image. Hair simulation is a highly a research oriented area and is still in its infant state when compared to other areas in computer graphics. There area many research efforts focused on hair simulation. Some of them focus on one aspect such as hair modeling, dynamics or rendering where as others were able to take the general problem into scope. Researchers has divided the current hair simulation models into four categories upon the under laying structure of the above said phases. The four main categories which hair simulation can be divided into are particle systems, volumetric textures, explicit hair models and cluster hair models[1].
So as for an introduction it is fair to say that hair represents one of the most fascinating creations of the Mother Nature which presents one of the most intriguing, mathematically complex and open research areas in computer graphics where an optimal solution even with the latest advancement of graphics based hardware is far from reach.
What is Hair and Hair Simulation?
A typical scalp of hair has about 100,000 to 150,000 hairs and in geometry hair is a thin curved cylinder having varying thickness. Each strand of hair can have any degree of waviness form straight to curly and the colors ranging form black to gray due to pigmentation and shininess. Due to the factors such as geometric intricacies of a hair, light and shadow interaction among hair, small scale thickness of individual hair compared to the rendered image, hair to hair and hair-body collisions hair simulation can be dissected in three major parts known as hair modeling, hair dynamics and hair rendering. Even though these processes can be taken into focus independently in real simulation environment these process are interleaved while processing hairs. Hair shape modeling phase deals with the overall geometry of the hair. It does this by creating thousands of individual hair and then altering the overall geometry of the scalp by using density, hair distribution, individual and overall orientation of hairs and complex hair-hair interactions and hair-body interactions. Once this phase is complete the geometry created by this phase is used by the other two phases to produce the final output. The hair dynamics phase addresses the movements of individual hair stands their collisions with other objects as well as with each other. In the field of virtual humans, hair possesses one of the most challenging rendering problems in computer graphics. The difficulties arise in hair rendering due to the amounts of hair, detail of geometry of an individual strand, complex light and shadow among the hairs and their small thickness when compared to the rendered image. Hair simulation is a highly a research oriented area and is still in its infant state when compared to other areas in computer graphics. There area many research efforts focused on hair simulation. Some of them focus on one aspect such as hair modeling, dynamics or rendering where as others were able to take the general problem into scope. Researchers has divided the current hair simulation models into four categories upon the under laying structure of the above said phases. The four main categories which hair simulation can be divided into are particle systems, volumetric textures, explicit hair models and cluster hair models[1].
So as for an introduction it is fair to say that hair represents one of the most fascinating creations of the Mother Nature which presents one of the most intriguing, mathematically complex and open research areas in computer graphics where an optimal solution even with the latest advancement of graphics based hardware is far from reach.
References
[1] Nadia Magnenat-Thalmann, Sunil Hadap, Prem Kalra, State of the Art in Hair Simulation, MIRALab, CUI, University of Geneva.
