# 原理化毛发 BSDF节点¶

Melanin concentration选项下的原理化毛发 BSDF节点界面。

## 毛发着色¶

Melanin concentration

• 白色 (黑色素值设为 $$0$$),
• 亚麻色 (黑色素值设为 $$0.25$$)
• 淡红色 (黑色素值设为 $$0.5$$)
• 棕色 (黑色素值设为 $$0.75$$)
• 黑色 (黑色素值设为 $$1$$)

## 输入选项¶

Hint

$\sigma_{a} = \frac{\ln(Color)} {\left(5.969 - 0.215\beta_{N} + 2.532\beta_{N}^{2} - 10.73\beta_{N}^{3} + 5.574\beta_{N}^{4} + 0.245\beta_{N}^{5}\right)^{2}}$

Hint

$melanin\_qty = -\ln(\max(1.0 - Melanin, 0.0001))$

Hint

The ratio formula is: $$eumelanin = Melanin*(1.0-MelaninRedness)$$, $$pheomelanin = Melanin*MelaninRedness$$.

$\begin{split}\sigma_{a} = eumelanin * \left[\begin{matrix} 0.506 \\ 0.841 \\ 1.653 \\ \end{matrix}\right] + pheomelanin * \left[\begin{matrix} 0.343 \\ 0.733 \\ 1.924 \\ \end{matrix}\right]\end{split}$

Hint

Hint

IOR

Hint

Hint

BSDF

## 参考文献¶

 [CBTB16] (1, 2, 3) Chiang, M. J. , Bitterli, B. , Tappan, C. and Burley, B. (2016), A Practical and Controllable Hair and Fur Model for Production Path Tracing. Computer Graphics Forum, 35: 275-283. doi:10.1111/cgf.12830
 [EFHLA11] d'Eon, E. , Francois, G. , Hill, M. , Letteri, J. and Aubry, J. (2011), An Energy‐Conserving Hair Reflectance Model. Computer Graphics Forum, 30: 1181-1187. doi:10.1111/j.1467-8659.2011.01976.x