Particle Cloud

Used to achieve effects such as gas or clouds. You can software render particles as thin gas, cloud, thick cloud, blobby surface or tube.

Volume material which can be connected to the volume port of a shading group. The initialParticleSE is a shading group that has a lambert material connected to its Surface port, and a particle cloud material connected to its Volume port. You can connect the particle cloud shading group to a particle emitter to achieve effects such as gas or clouds. You can software render particles as thin gas, cloud, thick cloud, blobby surface or tube.

Color, Transparency, and Incandescence can be set to a fixed value, or texture mapped over the particles’ lifetime. If mapped, the V values of the map are mapped onto the particles’ lifetime.

Transparency

Density

Similar to transparency; it controls how dense the cloud of particles appears to be, and therefore how much of the background can be seen through it. Increase this value to make the cloud more dense.

Blob Map

Specifies a scaling factor applied to the transparency of the particle cloud. You can connect a 3d texture to it in order to give some internal texture or shape to the cloud beyond what it gets from the particles.

Roundness

Controls the noise’s irregularity. The smaller the value, the less rounded the shape.

Translucence

Specifies a scaling factor for density that is used only to compute shadows. The larger the translucence value, the more light penetrates. The formula is:

density * (1 - translucence)

Built-in Noise

Noise: Controls the jitteriness within the particle cloud. If it is set to zero, the cloud looks very smooth and uniform throughout. As the amount of noise increases, the cloud appears noisier, like static on a television screen. Noise is set to 0.75, by default.
Noise Freq: Determines the size of the noise artifacts when Noise is turned on. Higher values of Noise Frequency produce smaller, finer artifacts, and lower values produce larger, coarser artifacts. If Noise Frequency is set to zero, that is the same as turning Noise off.
Noise Aspect: Controls the distribution of the noise (when Noise is turned on). It is zero by default, meaning the noise is equally distributed in X and Y. Positive values make the noise run perpendicular to the particle’s path. Negative values make the noise run more parallel to the path.
Noise Anim Rate: Specifies a scaling factor that controls the rate of built-in noise changes during an animation.
Solid Core Size: Determines the size of the core, which is the area where the particle is opaque.

Surface Shading Properties

Diffuse Coeff: Controls how much of the light in the scene is reflected from the particles. Most materials absorb some of the light falling on them, and scatter the rest.

The default value is 0.0. If you set this to 1.0, all the light falling on the material is reflected. Use a high value when creating dense clouds. If you set this to 0.0 (the minimum), no light is reflected and no surface shading occurs.

The surface color is modulated by the transparency. This value can be greater than 1.0, so the surface property can still appear even when the material is transparent.
Surface Color: Specifies the basic color of the particle cloud surface (as opposed to the inside of the cloud). Diffuse Coeff must be set to a value greater than 0 to enable this option.
Bump Mapping: Makes the surface appear rough or bumpy by altering surface normals (during rendering) according to the intensity of the pixels in the bump map texture. Diffuse Coeff must be set to a value greater than 0 to enable this option. (A bump map does not actually alter the surface. A silhouette of the surface appears smooth).
Translucence Coeff: Simulates the way light diffusely penetrates through translucent objects. This means that when light shines on one side of the object, the other side is partially illuminated. You can use this to create effects such as clouds, fur, hair, marble, jade, wax, paper, leaves, and so on. If you set Translucence Coeff to 0 (the default), no light shows through the object. If you set Translucence Coeff to 1, all the light shows through. Diffuse Coeff must be set to a value greater than 0 to enable this option.
Surface Shading Shadow: Determines if the surface shading is combined with the pre-illumination, which contains shadows, if enabled (see the Filter Radius attribute description next). Diffuse Coeff must be set to a value greater than 0 to enable this option.

Pre-illumination Controls

Filter Radius: Volumetric particles use pre-illumination, which evaluates the lighting at each particle’s center by default. This can sometimes cause popping if the illumination changes too fast in an animation, and is especially noticeable if Surface Shading Shadow is on.

Filter radius lets you filter the pre-illumination results so the value at each particle’s center is the average of all the pre-illumination results within the filter radius. Higher values increase render time but produce smoother images.