Particles geometry/generated ?

Hi guys, I was watching this video of a great nebula that was created vimeo.com/1121570, and read on in the comments and the creator said that “It’s mostly particle clouds (geometry, not generated)”, now I understood the rest of the comment, but I really have no idea what he meant by geometry not generated.

I was guessing at things like he used objects as opposed to points, or weight based on his geometry etc, im just not understanding what he meant by that line. If anyone could help me understand that it would be greatly appreciated, thanks a lot guys.:smiley:

PS: sorry for not creating a HyperLink guys, searching around the forums it appears I cant untill I have made 15 not link posts :smiley: