# Emission¶

Reference

Panel: Particle System ‣ Emission

The Emitter system works just like its name says: it emits/produces particles for a certain amount of time. In such a system, particles are emitted from the selected object from the Start frame to the End frame and have a certain lifespan. These particles are rendered default as Halos, but you may also render these kind of particles as objects (depending on the particle system’s render settings, see Visualization).

## Options¶

The buttons in the Emission panel control the way particles are emitted over time:

Number
The maximum amount of parent particles used in the simulation.
Start
The start frame of particle emission. You may set negative values, which enables you to start the simulation before the actual rendering.
End
The end frame of particle emission.
The lifespan (in frames) of the particles.
Random
A random variation of the lifetime of a given particle. The shortest possible lifetime is Lifetime × (1 - Random). Values above 1.0 are not allowed. For example with the default Lifetime value of 50 a Random setting of 0.5 will give you particles with a live span ranging from 50 frames to $$50 × (1.0 - 0.5) = 25$$ frames, and with a Random setting of 0.75 you will get particles with live spans ranging from 50 frames to $$50 × (1.0 - 0.75) = 12.5$$ frames.

### Emission Location¶

Emit From parameters define how and where the particles are emitted, giving precise control over their distribution. You may use vertex groups to confine the emission, that is done in the Vertex Groups panel.

Vertices
Emits particles from the vertices of a mesh.
Faces
Emits particles from the surface of a mesh’s faces.
Volume
Emits particles from the volume of an enclosed mesh.

### Distribution Settings¶

These settings control how the emissions of particles are distributed throughout the emission locations.

Random
The emitter element indices are gone through in a random order instead of linearly (one after the other).

For Faces and Volume, additional options appear:

Even Distribution
Particle distribution is made even based on surface area of the elements, i.e. small elements emit less particles than large elements, so that the particle density is even.
Jittered

Particles are placed at jittered intervals on the emitter elements.

Particles/Face
Number of emissions per face (0 = automatic).
Jittering Amount
Amount of jitter applied to the sampling.
Random
Particles are emitted from random locations in the emitter’s elements.
Grid

Particles are set in a 3D grid and particles near/in the elements are kept.

Invert Grid
Invert what is considered the object and what is not.
Hexagonal
Uses a hexagonal-shaped grid instead of a rectangular one.
Resolution
Resolution of the grid.
Random
Add a random offset to grid locations.

Tipp

Your mesh must be manifold to emit particles from the volume.

Some modifiers like the Edge Split Modifier break up the surface, in which case volume emission will not work correctly!

Use Modifier Stack

Take any Modifiers above the Particle Modifier in the modifier stack into account when emitting particles, else it uses the original mesh geometry.

Bemerkung

Note that particles may differ in the final render if these modifiers generate different geometry between the viewport and render.