The Ghostbusters reboot has been one of few recent remakes that’s been well-received (unless you’re one of these misogynist pricks who took exception to female actors playing the lead roles). While the visual effects aren’t as groundbreaking as those in the 1984 original were at the time, there is an interesting story behind the design of the ghosts.

Before production started, the studio behind the film – Sony – asked VFX houses pitching to work on the film to design an animated ghost as a guide to what the firms though those in the final film should look like – letting them in on the art direction of them film.

“The brief allowed us quite a bit of flexibility,” says VFX Supervisors Glenn Melenhorst from Illoura, who won the pitch along with Song Pictures Imageworks, MPC and Zero. “We developed some designs that evoked a creepy, ethereal look and feel, but still had enough charm and personality to work for the comedic aspects of the film.”

Ghostbusters VFX breakdown

Illoura has just released a VFX breakdown showing its work on the film across three sequence – a redo of one of the original film’s iconic scenes, a mirror full of ghouls and a big ghost-creature who appears during a rock show. Here’s what they told us about them:

Ghostbusters VFX: The Library

For Gertrude, a live-action/CG hybrid (sometimes full CG) who ‘lives’ in the library, artists built a skeletal system, designed and added her clothes and lower body, and finished with a celestial aura. Production employed a technique of strapping the actors in LED lighting which threw a soft light both onto the actors as well as the set, which required artists to integrate her seamlessly into the plate. They also transformed her from ethereal beauty to skeletal ectoplasm-spewing-monster.

Ghostbusters VFX: Mirror Ghouls

Another Iloura creation was the band of Mirror Ghouls. The filmmakers envisioned them as decomposed creatures recessed in a dark world who take on a suggestive form from afar, but become more legible as they approach the mirror surface and try to escape.

To achieve this, Iloura’s artists developed a number of looks for the translucent creatures from the recessed world, as well as more creepy, human-like forms that appear close to the surface. Cooler shading and lighting tones were utilized behind the glass, which shifted to warmer tones as the ghouls approach the surface; a technique that helped inform the audience of their other-worldly environment and their relationship to ours.

As the ghouls eventually smash through the mirrors and take on vaporous ethereal forms, CG warping and reflective bows were added to the mirror surfaces, as well as practical and CG smashed glass to support the physicality of the event. This kind of seamless transition was key to audience acceptance in this film as ghosts and ghouls frequently metamorphose from one form to another.

Ghostbusters VFX: The Heavy Metal Show

Mayhem, a large and ominous all-CG ghost who inhabits a concert stadium and appears as part of a heavy metal stage show, was another Illoura creation. He needed to retain a ghostly, translucent look, but with subtle real-world detail such as skin texture and hair which needed to float and move as he flew through the air. An internal glow dubbed a “jelly pass” was added to give him an inner ghostly glow on top of his skeleton and muscle system. In some of the more complex shots, the dry-ice aura and vapor effects needed to interact with the concert crowd and the main actors to bring more believability to the scene.

Further work to this sequence included CG beams, sparks and lightning from the actors guns, crowd enhancements and associated integration between the live-action plates and the CG work.

Other characters completed by Iloura include ghost rats (below) and the Show Ghost featured in a sequence with Bill Murray’s character.