These are caused by self-intersecting bits of the cloud particles showing the backsides of faces to the outside world:



Rays going through the back of a face don't count as going into the volume, and so appear mostly transparent.

To fix this you have a couple options:


Lighten up on the displacement to avoid such intersections:


Or add a remesh modifier (and optionally a decimate modifier to keep the vertex count down)




Volume scatter shader causes black spots
It seems like building the Robocop was a really stupid business approach:


You can't build them on industrial scale (to put it somewhat insensitively, OCP didn't have a ready supply of highly trained and freshly killed police officers)

So, Robocop seemed like a prototype that could never have entered production. Total waste of R&amp;D money.
And having a police brain (because he already know police procedure) seems not necessary since at the same time OCP could build fully AI robots (from robot chicken, flawed as it was, in Robocop 1, to Ninja Androids in Robocop 3).

