Volume Scattering
This is a global tint for all volumetric lighting effects (this doesn't include global fog).
Both examples show a scene illuminated by a physical combination of sun and sky. In the left image, an orange hue was used for the Redshift Environment object. On the right, a bluish hue was used. By mixing it with the reddish sunlight, the resulting hue there looks greenish.
Defines how strong the volumetric lighting effect should be. Higher values will generate brighter volumetric lighting and vice-versa. If you enable volumetric scattering and you get a completely washed-out-white frame, you might need to reduce this setting significantly.
Controls both the strength of the fog and the amount by which light gets attenuated as it travels through the medium. Higher numbers introduce stronger fogging and more light attenuation. This is especially useful for the Emission function (see below) to increase the visibility of ground fog.
Lighting attenuation only happens for non-infinite lights. Dome lights, the physical sun and infinite lights will not be attenuated. This is intentional! Because these lights are at an infinite distance, any amount of attenuation (which is dependent on distance) would completely block them out.
The left rendering uses an Attenuation value of 0.0 and the right side a value of 0.25.
This parameter controls how much the lighting will bounce around inside the medium and get scattered. In some ways, this setting is similar to the "Diffuse/Specular" settings of a surface material.
An Anisotropy value of 0.0 means that the lighting will bounce around more and will appear more diffuse. Values greater than 0.0 produce what is known as "forward scattering". Forward scattering means the lighting doesn't bounce around in the medium as much and is mostly visible when travelling towards the camera. On the other hand, negative numbers will produce "backward scattering' which means that volumetric lighting will mostly be visible as it travels away from the camera.
From left to right, these renderings used Anisotropy values of -0.5, 0.0 and 0.5.
As you can see in the next image, the Anisotropy effect isn't that strong when viewed from the side.
From left to right, these renderings used Anisotropy values of -0.5, 0.0 and 0.5.
Allows fog to be self-illuminating. This is useful when you want the fog to have color and not just be black.
The default black Emission is used on the right. The two other images used blue and red for Emission.
Since the fog can be self-illuminating via the Emission setting, this option ensures that, if the Redshift Camera uses photographic exposure, the Emission color will be scaled appropriately so that the user won't have to use large RGB numbers.
We strongly recommend users leave this option enabled.
With a Height of 0, the fog fills the entire room. Otherwise, the desired height to which the fog should reach can be entered.
Examples of different Height values for the Environment fog.
When using height fog on a large-scale scene, there might be a sharp shading line where the fog joins the horizon. Even though "correct" this effect is not visually appealing. The Horizon Blur setting allows the Height fog's horizon to be faded out which will smooth out the effect.
If activated, you can control the orientation and location of the fog by moving the Redshift Environment object directly in your view. If deactivated, you can set a starting point and direction for the fog by using the Ground Point and Ground Normal parameters.
In the left image, the orientation of the fog ground plane was indicated by a red area. The right image shows the rendered result. The fog condenses behind the city at the left edge of the image. This leaves the city side oriented to the sun of the physical sky more visible.
If Use Transform is switched off, a position can be set here through which the ground plane for the fog calculation should pass.
This vector describes the direction in which the fog should spread. Since directions can also be set here, e.g. along the X or Z axes, vertically standing height fogs can also be created.
Defines how much fogging and volumetric lighting should be applied to rays that hit scene objects.
Defines how much fogging and volumetric lighting should be applied to rays that were spawned from reflection.
Defines how much fogging and volumetric lighting should be applied to any GI lighting. Applying volumetric lighting on GI computations can wash out the results, produce noise (especially if strong phase settings are used) and be computationally intensive. For this reason, Redshift has this contribution turned off by default.
Defines how much fogging and volumetric lighting should be applied to rays that don't hit anything and go to infinity.
This option replaces environment alpha with 1. This is because alpha pre-multiplied output can make the volumetric effect disappear in areas where the alpha is not 1 or 0. You should only disable this option if you expect to composite and effectively replace the volumetric effect where the environment is.
On the left you can see the rendered examlpe image. The center shows the alpha channel of this rendering when Replace Alpha is active. The channel is completely white. When this option is switched off, the alpha masks of the light objects and geometries are visible.