Graphics Reference
In-Depth Information
R (
p
= 0)
df
R
g
dh
g
g
t
h
g
t
g
g
t
TT (p = 1)
df
TT
g
t
df
TRT
g
TRT (
p
= 2)
Figure 8.56
Light reflection and transmission of a hair fiber as viewed along the axis of the hair fiber.
Although it is circular in this figure, the general model has an elliptical cross section.
(From [Marschner et al. 03] c
2003 ACM, Inc. Included here by permission.)
A complete physical analysis of scattering from hair fiber is very complicated.
Marschner's model is relatively simple, yet captures the physical characteristics
essential to realistic rendering. Figure 8.57 shows rendering of a geometric model
of human hair with the Kajiya-Kay model and the Marschner model compared to
a photograph. The geometric model of the hair fibers used in these renderings is
approximate. The authors did not attempt to match the more random orientation
of fibers visible in the photograph (this problem is considered in Section 8.6). As
(a) Kajiya-Kay model (b) Marschner model (c) Photograph
Figure 8.57
Comparison of renderings using the Kajiya-Kay model, the Marschner model, and a pho-
tograph. (From [Marschner et al. 03] c
2003 ACM, Inc. Included here by permission.)
