体积散射

体积散射 节点允许光线在通过体积时产生散射现象。为场景添加雾效果是一个典型的用法。它也可以与 体积吸收 节点一起使用来制作烟雾效果。

输入

颜色

Scattering coefficients per color channel.

密度

散射效果的密度。

各向异性 Henyey-Greenstein Draine

Controls the relative amount of backward and forward scattering.

折射率 Fournier-Forand

Refractive index of the scattering particles relative to water. Common ocean waters range between 1.0 and 1.2, while turbid waters with higher density of particles have higher IORs.

反向散射 Fournier-Forand

Fraction of light that is scattered backwards. Most oceanic particles have backscatter values between 0.001 (e.g., very large phytoplankton) and 0.1 (e.g., very small mineral particles), pure water has a backscatter of 0.5. Values taken from Ocean Optics Web Book.

Alpha Draine

Blending factor between Henyey-Greenstein (\(\alpha = 0\)) and Cornette & Shanks (\(\alpha = 1\)) phase functions.

直径 Mie

Diameter of the scattering particles in µm.

属性

相位

体积散射相位函数。

Henyey-Greenstein:

Simple and widely used phase function, useful for approximating scattering in biological tissues.

Fournier-Forand:

Cycles Only Suitable for modeling the scattering of light in underwater environments.

Draine:

Cycles Only Suitable for modeling the scattering of interstellar dust.

Rayleigh:

Cycles Only Describes the scattering by particles with a size smaller than the wavelength of light, such as the scattering of sunlight in earth's atmosphere.

Mie:

Cycles Only Describes the scattering by particles with a size larger than the wavelength of light, such as cloud and fog.

Tip

These phase functions can be combined using a 混合着色器.

Volume scattering phase as a function of angles between the incoming and the outgoing direction, in logarithmic scale. Light comes from the left side.

输出

体积/音量

体积吸收着色器节点的输出接口必须与 材质 或 世界 输出节点的 体积（音量）输入 连接。

示例

体积散射着色器节点效果。