Single-cell vs. multi-cell controls in Motion

If a particle system has only one cell, the Emitter Inspector displays both the Emitter Controls and the Cell Controls. In this case, you can control every aspect of the particle system from a single Inspector.

However, when a particle system has two or more cells, the Emitter Inspector replaces individual cell controls with a group of Global Controls, which are located below the Emitter Controls and are hidden by default. (The Cell Controls are still available in the Particle Cell Inspector.)

Changes made using the global controls modify the effect of each cell’s parameters relative to the other cells in the system. For example, in a particle system with three cells that have different Scale values, increasing the Scale parameter in the Emitter Inspector multiplies the Scale value of all three cells by the same percentage. This has the result of increasing or reducing the size of every particle in the system, while keeping the size of each particle relative to one another the same. For this reason, the global control values of multi-cell particle systems appear as percentages.