Visibility
These controls establish a range where particles are visible. Distances are defined by how close or far away the particles are from the camera. It can be used to fade out distant or near particles. The units for these values are determined by After Effects' camera settings.
Far Vanish
When particles are this far from the camera, they are not visible.
Far Start Fade
This is the point when particles start to fade out.
Near Start Fade
This is the point where particles start to fade out.
Near Vanish
When particles are this close to the camera, they are not visible.
Near & Far Curves
Allows for selecting Linear or Smooth interpolation curves. With Smooth, the visibility for the form will fade less gradually than with the Linear option.