Trapcode Particular

Layer Maps Group

Size group

The Size group lets you change the size of system particles by using a source layer's luminance values. Black regions of the layer image will have a particle size of 0, which creates holes in the field. White regions have their particle size set to the maximum value of the Particle group > Size control.

A layer with a gradient ramp (left), a particle field with Particle Size set to 8 (middle), and the gradient ramp applied as the Size map with Map Over set to XY (right).