Graphics Reference
In-Depth Information
geometry in realistic rendering has already been noted; hair rendering reaffirms
the significance of this connection. However, it is still difficult to leverage this
kind of local geometric structure in a practical manner for production rendering.
One critical aspect of hair rendering that has been omitted entirely in this dis-
cussion is the issue of hair dynamics—hair fibers move around in reality. In the
visual effects area, it is still difficult to make the appearance of hair believable in
digital doubles. At the present time this is done by hand with specialized tools.
The method of capturing local hair structure could be very useful for this. How-
ever, there is still the problem of animating a geometric hair model. This remains
a problem because of the complex interaction between hair fibers as they move.
Factors as diverse as hairspray to static electricity to local airflow all affect the
animation of hair. In summary, it can be said that closer links between the three
components—geometry, color, and dynamics—may well bring the next level of
realism to hair rendering.
Until recently, hair rendering relied on established existing methods. Once
researchers started looking to modern physically based methodologies the field
Figure 8.81
Rendered images of the hair geometry reconstructed by the method of Wenzel Jakob et al.
using the image-based hair reflectance model. ( c
Arno Zinke, GfaR mbH.) (See Color
Plate XXI.)