Рассеивание объёма (volume scatter)

Нода Volume Scatter позволяет свету рассеиваться при его прохождении сквозь объём. Типичным примером использования ноды может служить добавление в сцену тумана. Также она может использоваться совместно с нодой «Поглощение объёма» для создания дыма.

Входы (inputs)

Цвет (color)

Scattering coefficients per color channel.

Плотность (density)

Интенсивность эффекта рассеивания.

Anisotropy Henyey-Greenstein Draine

Controls the relative amount of backward and forward scattering.

IOR 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.

Backscatter 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.

Diameter Mie

Diameter of the scattering particles in µm.

Свойства (properties)

Фаза (phase)

Volume scattering phase function.

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.

Совет

These phase functions can be combined using a Смешивающий шейдер (mix shader).

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

Выходы (outputs)

Объём (volume)

Выход Volume должен быть подключён к входу Volume ноды Material Output или World Output.

Примеры

Пример объёмного рассеивания.