Particles

Use

Sets the number of particles to be shot for the scene. A text field lets you key in a value for millions of particles.

This setting is one of the most important settings involved in particle tracing and directly controls the execution time and the quality of the solution. Time taken to compute a solution increases nearly linearly with the number of particles. That is, a solution using 2 million particles will take nearly twice as long as a solution using 1 million particles.

Typical settings for the number of particles for a reasonable size design could be:

• 0.1 million (100,000) particles — for a low-quality test.

• 1 to 2 million particles — for a medium quality solution.

• 10 to 30 million particles (or more) — for a high quality solution.

Extremely large or complex models may require much larger numbers of particles.

Maximum Bounces

(Visible only when Show Advanced Settings is on.)

Sets the maximum number of times a particle can reflect off surfaces, or bounce (default 100).

If set to a value of 0, then the solution will display the results of direct illumination only.

Illuminate Both Sides of Surfaces

(Visible only when Show Advanced Settings is on.)

Lets you control whether or not surfaces collect light on both sides.

• If on — both sides of surfaces are illuminated in the solution.

• If off — only the side with positive surface normals (normals pointing outward from the surface) is illuminated. You can change the direction of surface normals with the Change Normal Direction tool, located in the Modify Surfaces tool box.

Normally, this setting should be on, unless all objects in the scene are solids. For solids, only the outside surfaces are illuminated, irrespective of this setting.

Ray Trace Direct Illumination

(Visible only when Show Advanced Settings is on.)

If on, the ray tracer is used to compute shadows from light sources, but not from reflected light.

Receiver Reflects Light

(Visible only when Show Advanced Settings is on.)

Lets you control whether or not surfaces reflect light during the calculation of a solution. This setting is found also in the Radiosity dialog box.

• Always
— All surfaces in the design can reflect light.

• If global illumination on
— A surface reflects light if Global Illumination is turned on in its material definition.

• If global illumination off
— A surface reflects light if Global Illumination is turned off in its material definition.

In general this setting should be set to Always, unless materials have been set up explicitly to allow selective surfaces to participate in the solution.