Hello and welcome to another V-Ray feature short demonstration. In this first
video we will look into the volumetric effects in V-ray, such as the VRayEnvironmentFog
and the VRayAerialPerspective. In a second part, we will
examine the VRayVolumeGrid, which allows for loading and rendering volumetric
cache files, such as OpenVDB, Field3D and PhoenixFD aura files.
The purpose of a volumetric effect is to simulate the way light scatters from
particles in the atmosphere.
The longer light travels in the atmosphere, the more it scatters. As a
result, objects that are far away appear less visible compared to those that are nearby.
Let's take a closer look at the VRayEnvironmentFog.
It is a volume shader, which can be applied to specific objects or globally
to the whole scene.
It scatters light from both direct light sources and indirect illumination (GI).
It is created and adjusted from the Environment and Effects window.
By default, the effect is applied on the whole scene and can be limited by height
from the “fog height” parameter. Note that if the camera is above the height limit,
the volume boundary will be clearly visible.
In this example the camera’s Z coordinate is about 2 m, so let’s
raise the “fog height” to a bit more than that.
Alternatively, the fog can be restricted to a volume defined by a geometry
geometry object from the “Gizmos” list.
The overall density of the fog is controlled by the “fog distance”
parameter. Lower values make the fog thicker.
And higher values make it more transparent.
In addition, the density can be controlled by plugging a 3D map in
the “fog density” map slot. By increasing the “step size” parameter, you can speed up
the render at the expense of precision.
The color of the fog can be set from the “fog color” swatch.
Currently, the fog isn’t scattering indirect illumination. By enabling the
“scatter gi” checkbox, the light coming from the environment, a V-Ray sky
texture in this case, will illuminate the fog. And the “scatter bounces”
controls how many bounces of indirect illumination should be scattered
in the fog.
Although this increases the realism, it requires more calculations and slows
down the render. That is why a similar, but less accurate, effect can be
achieved by plugging a bright blue color in the “fog emission” map slot.
The fog can be optimized further, by disabling its contribution on different
shading aspects of V-Ray, such as background,
reflections, refractions, shadows and global illumination. While in this
example the VRayEnvironmentFog is set to simulate atmospheric fog, it can
be used to create effects such as God-rays, volume light, clouds and other
complex volumetric effects. With its many functions
functions it is a powerful tool, yet for simpler effects it may be somewhat time consuming
to set up.That is why as of version 3.3 in V-Ray for 3ds Max, there
is a new, fast to set up and render, environment fog type of effect called
“Aerial Perspective”.
Let’s have a look at it. Its purpose is to achieve the same effect of light
scattering from the atmosphere, but with less parameters to tweak and faster
rendering speed. It has only four parameters:
1.“visibility range” - to control the density; 2.“atmosphere height” – to set the vertical limit for the effect
3.“inscattered light intensity” which is a multiplier for the emission of the fog
4.and the “affect environment rays” checkbox that enables this effect to occlude
background and simultaneously scatter illumination from the environment.
Let’s load up a more complex scene so we can see the new “Aerial Perspective”
effect in action.
As of version 3.3 of V-Ray, there is a new sky model called “Hosek” that is used in this
scene. When used in conjunction with "Aerial perspective" we could achieve more
natural results.
In this short video tutorial, we have covered the volumetric effects in V-Ray together
with their essential parameters for fine control such as density, height, emission
and color.
I hope you have found this video useful and helpful. Make sure you check out more
V-Ray featured videos. Thanks for watching.