RedSDK supports one Volumetric Environment type:

• ray cutoff is an optional value to stop the ray propagation when the result value is below the threshold.
  
• ray marching step is the size of a single volume step along the ray used when sampling the medium. Decreasing this value will increase the rendering quality and time, especially for heterogeneous media.
• scattering samples defines the number of samples that will be used to sample the volume during its illumination process with surrounding lights. Increasing it increases the volume rendering quality and time.
  
  

Structure of ‘volume shape’ shader.

This shader includes the following items: Effects, Volumetric effect, Sigma coefficients, Color canals, Boundary shape (Sphere, Cube or None).

A custom heterogeneous media in a spot light volume

Effects

The scene without medium

Basic homogeneous volumetric effect

Volumetric effect

Volumetric effect shader parameters

Activated - switch on/off the volumetric effect

Light volume only - render light volume only

Density - density of the medium (0 – 100%)

Noise affect - noise factor (0 – 100%)

Noise octaves - Increasing the number of octaves increases the level of noise details.

Noise scale - noise zoom

Noise type - noise algorithm (Perlin or Worley)

Sigma coefficients - ‘Sigma coefficients’ shader

Boundary shape - boundary shape (None, Sphere, Cube)

Sigma coefficients

Sigma coefficients shader parameters

Absorption - absorption coefficient

Scattering - scattering coefficient

Scattering-in – scattering coefficient, (used only if Scattering = 0)

Scattering-out – scattering coefficient, (used only if Scattering = 0)

Color channels (absorption) – ‘color channels’ shader for Absorption (used only if Absorption = 0)

Color channels (scattering) – ‘color channels’ shader for Scattering (used only if Scattering = 0)

Color channels (scattering-in) – ‘color channels’ shader for Scattering-in (used only if Scattering-in = 0)

Color channels (scattering-out) – ‘color channels’ shader for Scattering-out (used only if Scattering-out = 0)

Color canals

Color canals shader parameters

Affect - color affect (0 – 100%)

Red – red canal

Green – green canal

Blue – blue canal

Boundary shape (Sphere, Cube)

Boundary shape (Sphere) parameters

Centre - centre radius

Radius - sphere radius

Boundary density law – the law of the density changing near the surface of the boundary shape

Boundary density distance – distance to the surface of the boundary shape (0 – 100%)

Boundary density affect - affect of density’s change (0 – 100%)

Near - boundary layer only - switch on/off taking into account only the layer near the surface of the boundary shape 

Near - boundary layer width – width of the layer near the surface of the boundary shape (0 – 100%)

Boundary shape (Cube) parameters

Min – first point of the box

Max - Second point of the box

Boundary density law – the law of the density changing near the surface of the boundary shape

Boundary density distance – distance to the surface of the boundary shape (0 – 100%)

Boundary density affect - affect of density’s change (0 – 100%)

Near - boundary layer only - switch on/off taking into account only the layer near the surface of the boundary shape 

Near - boundary layer width – width of the layer near the surface of the boundary shape (0 – 100%)

Scattering medium.

Evironment may be Homogeneous or non-homogeneous medium with shadow.

Examples of Environmental turbulence with using the Prelin, Worley noise algorithms

It is possible to set up the environment inside the boundary shape (sphere , cube).

It is possible to use only the layer near the surface of the boundary shape.

It it is possible to Decrease/increase the environment density moving to the surface of the boundary shape.

Examples of combining multiple volumetric effects (each effect has their own settings and boundary shapes).

Light scattering.

Support spot, point, beam light sources

It is possible to create atmospheric effects (luminescence of celestial bodies, halo effects etc. )

It is possible Change the color of the rays when passing through the colored glass

It is possible to take into account only the highlighted space

Example of enabling or disabling the volume rendering during the global illumination

It is possible to create renders in holograms-like style

Known problems

1. Error message when all volumetric effects are switched off.
    
2. Disappearance of background image when volumetric effect is switched on.