Gray Horsfield

Gray Horsfield was a member of Weta Workshop who worked with conceptual digital visualization for Peter Jackson's two film trilogies. More recently than The Lord of the Rings, he also was part of the crew for Iron Man 3 and Man of Steel.

In the second disc-appendix of The Fellowship of the Ring, Horsfield and Jim Rygiel explain Weta Digital's use and composition of "particle systems" for making the effects of the Balrog's fire in Moria.