Particle Emission Property Editor

Particle Emission Property Editor

Applies general particle emission characteristics to objects, such as particle speed, density, and spread angle. It also gives you access to a property set that lets you define the particle stream (called a particle type) that is emitted, in terms of its rendering characteristics, environmental forces that act on the particles, and particle decay.

For information in general about particle emissions, see Setting Up the Particle Emission [ Particles ].

To display: Select a particle cloud and choose Modify > Particles > Set Emission from the Simulate toolbar, then pick an emitter object. You can also select a particle emitter object and choose Modify > Particles > Edit Emission.

The Fluid Emission page that appears in the Fluid Property Editor when you create a fluid particle cloud contains the same parameters as for this Particle Emission property editor.

If you create a particle event with emitted particles, the event’s Emission property page that appears is similar to this one, but with some different parameters. See Event Emissions for more information.

Any parameter with a connection icon can have its values modified by a connected weight map (and texture map for color parameters).

For all parameters that have a Var parameter associated with them, see Particle Variance and Seed Parameters for more information.

Overview

This page contains the most frequently used emission parameters, allowing you to quickly set up or view the emission. Each of these parameters are the same ones that are on the Emission page.

You can change the parameter values either on the Overview page or on the Emission page; either way, the parameter of the same name on the other page is immediately updated.

Emission

Name	The name of the emission property. By default, this is the name of the object used as the emitter with an Emission suffix appended.
Mute	Temporarily deactivates the particle emission (emission properties).

Particle

ParType	Displays the name of the particle stream currently applied to the particle emitter. Click New to define a new type, or click Edit to modify the one listed. Either way, the PType (Particle Type) Property Editor appears for that particle.
Generation	Specifies where the particles originate from, according to the geometry of the emitter object. Point: Particles originate from the points of the emitter object. Line: Particles originate from the edges (for polygons) or U/V isolines and boundaries (for NURBS) of the emitter object. Surface: Particles originate from the entire surface of the emitter object. Volume: Particles originate from within the volumetric boundaries of the emitter object. Fluid: Particles are emitted from the implicit fluid emitter object.
Direction	Specifies the direction in which the particle stream is emitted. Emission direction can be relative to the emitter object’s local or global reference or relative to the direction of the emitter object’s normals.
Rate	Controls the number of particles emitted per second. This parameter also has a Var parameter so that you can produce a more random effect on the particles. On the Distribution page, you can also set this parameter’s Distribution method (Uniform or Gaussian), as well as set a Seed value. See Particle Variance and Seed Parameters for more information on these parameters.
Spread	Controls the diameter of the aperture through which particles are emitted from the emitter object. Range is 0 to 180 degrees. This parameter also has a Var parameter so that you can produce a more random effect on the particles. On the Distribution page, you can also set this parameter’s Distribution method (Uniform or Gaussian), as well as set a value. See Particle Variance and Seed Parameters for more information on these parameters.

Velocity

These parameters also have Var parameters so that you can produce a more random effect on the particles.

On the Distribution page, you can also set the parameter’s Distribution method (Uniform or Gaussian), as well as set a Seed value.

See Particle Variance and Seed Parameters for more information on these parameters.

Speed

Controls the initial speed of emitted particle in SOFTIMAGE units per second.

Inherit

Controls the velocity of the particle emissions from an animated 3D object or moving vertices that you are using as a source.

You apply a percentage value that is relative to the velocity of the source; that is, the emitted particles inherit the specified velocity from the moving source.

If you specify a value greater than 100, for example, the particles are emitted at a greater velocity than the source itself, causing them to speed ahead of the emitter. Values of less than 100 cause the particles to trail behind the emitter.

Orientation

Sets the rotation angle (in degrees, counterclockwise) at which the particles are initially emitted. The rotation is updated at every frame using the Rotation Velocity defined on the General page in the PType property editor.

For more information, see Rotating Particles [ Particles ].

These parameters also have Var parameters so that you can produce a more random effect on the particles. On the Distribution page, you can also set the parameter’s Distribution method (Uniform or Gaussian), as well as set a Seed value. See Particle Variance and Seed Parameters for more information on these parameters.

Billboard	Sets the rotation of the particles as they’re emitted. The particles are displayed as billboards (2D). The range is -360 to 360 degrees.
Roll	Sets the particle’s rotation around its Z axis as it’s emitted. The range is -360 to 360 degrees.
Pitch	Sets the particle’s rotation around its X axis as it’s emitted. The range is -360 to 360 degrees.
Yaw	Sets the particle’s rotation around its Y axis as it’s emitted. The range is -360 to 360 degrees.

Color

Map Color

Lets you use the color values from a weight map or texture map (see in the guide) that is connected to this option (click its connection icon and select a map). When you select Map Color and connect a map, the colors on the map are used to set the initial color of each emitted particle. In this case, the particle’s color set on the Color page (see Color) is not used.

Distribution

This page contains the Distribution and Seed parameters for all emission parameters that have accompanying Var parameters. The Var parameter values add variance to their accompanying parameter’s value.

For more information, see Particle Variance and Seed Parameters.

Distribution

Uniform or Gaussian are methods of how the variance value is distributed.

Uniform	Numbers are distributed uniformly around the parameter’s value using the Variance value. The parameter will always be in the range [value - variance; value + variance], never outside of it.
Gaussian	Numbers are distributed as a Gaussian bell curve around the parameter’s value using the Variance value. Most numbers will be in the range [value - variance; value + variance], but they may be outside of that range with [value - variance], and they will be outside of that range with [value + variance].

Seed

Introduces even more variation to the Var parameter values, in case you didn’t already have enough. The Seed allows you to have very fine control over parameters, changing them slightly without having to change the parameter’s value or Var(iance) value.

The Seed parameters work only if you have a value other than zero for its accompanying Var parameter.

Sub-Frame Emission

Adds particles between frames (oversampling) when, for example, you are emitting particles from a fast-moving emitter. When you oversample the particle emission, you can specify how many times per frame you want to emit particles.

Randomize Position

Does a random spreading of the particles between two successive positions of emission. For a given particle, the emission position is computed in 3D space at the current frame (or subframe) and the frame (or subframe) before. The particle is randomly positioned on the line joining these two points.

This lets you do oversampling without much cost to the calculation time, but you have little control as to how the oversampling is done.

Steps

Number of emissions to occur per frame (1 is the default). For each subframe, a certain number of particles are emitted at the locations specified by the position of the emitter at this subframe. This lets you spread the particles in a controlled manner and still have some puffs, if you like.

Stratified Emission

Emits particles in distinct strata (layers). If you emit particles with identical speed from a grid, you’ll see distinct planes of particles; if you emit from a sphere, you’ll see concentric spheres of particles, etc.

Because this option takes into consideration the geometry of the emitter, you need to use Surface as the Generation type (on the Emission page in this property editor).

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