Arriving At the shot

Framestore’s VFX supervisor Ivan Moran on making aliens vanish

Arrival features a series of 12 alien spaceships in the shape of obsidian stones appearing throughout the world. The final 10 shots of the sci-fi movie needed to be reconceptualised so VFX supervisor Louis Morin hired Framestore to execute the ships’ departure sequence.

“Our biggest challenge was selling the idea of scale,” notes Framestore VFX supervisor Ivan Moran. “These ships are over a thousand feet long, but devoid of any recognisable external architecture that could assist us with scale. On top of that we wanted to have them disappear in a way that didn’t feel too arbitrarily tricksy or magical. I came across a couple of natural phenomenons that I thought would work quite well. One is called a condensation effect, which is a sudden drop in temperature and pressure that sometimes occurs when aircraft are coming in to land and you get incredible rolling fog banks along the wings, which in some cases can envelop the whole back of the aircraft. I thought that was a cool way of helping to disguise the ship by covering it with a natural cloud-like phenomenon so it’s not literally dissolving off of a plate, but instead melding with the clouds in the sky.”

The condensation effect is often accompanied by a low-temperature mirage effect called a Fata Morgana. “Using that mirage effect allowed our compositors to prevent anything feeling like a straight dissolve because I was able to break up the ships into interesting patterns,” says Ivan.

Keeping this effect as slow as possible helped make the alien ships feel mysterious. “We ended up doing a test that was mastered to about 30 seconds which Denis loved. It was happening so slowly you couldn’t tell where it all was coming from, nor quite what was happening, which was perfect. The test shot happened to be on an overcast day. All of the other locations had different lighting and cloud covers. We finely tuned the mirage and

condensation effects so they were based on the same idea, but had slightly different looks depending on the weather conditions in the plate. For the sunset ones you got to do some beautiful key lighting as the clouds begin to form and cover ships. Then in shots where there were no clouds, the simulations we ran were more cirrus-based.”

Four to five different high-resolution fluid simulations needed to be produced per ship. The key was running these simulations at 48fps for scale. “The project was finishing so we knew we were going to have to use a lot of compositing work to choose bits of simulations from different versions and marry them together,” says Ivan. “Covering the ships with these condensation-based clouds worked perfectly in disguising the ship, and allowed them to disappear in an interestingly organic and complex way.”

The surface of the ships couldn’t be reflective, Ivan explains: “We used physically plausible shading techniques so as the clouds crept over they affected the surface of the ships. It wasn’t a straight reflection but more of a subtle shadowing. The mirage effect led the clouds; it was always in front so you didn’t have white clouds covering a black ship which would have been difficult to integrate.”

The ship asset was created by Oblique FX, which meant Framestore needed to do an asset diagnosis, rendering some frames close up and at distance. “We had a fast two- or three-day turnaround to make sure that we could render the ship in shots and it would match,” comments Ivan.

Ivan explains repetition became a hurdle to overcome: “If we had to watch 12 ships slowly disappearing, the audience could potentially become bored. We worked closely with Joe Walker, the editor, in coming up with a plan. I had the idea of advancing the edit a little bit so if the whole event is 30 seconds we’ve compressed it down to 10 seconds by subtly jump cutting our way through. We repeated that again but jumped cut quicker until the moment when you wanted to see the whole thing. The ship in Montana comes on, which was our test shot: It’s about 20 to 30 seconds long and you get to see the entirety of the effect,” says Ivan, adding: “even though Arrival is a science fiction film it was exciting to ground the ships disappearing into something that is based on reality.”

It was exciting to ground the ships disappearing Into something that Is based on reality Ivan Moran, VFX supervisor, Framestore

framestore used houdini and Maya for fluid sims: “now that Maya’s fluid dynamics kit is so impressive we tend to use it for anything that’s organic such as cloud-based work,” says vfx supervisor ivan Moran

Nuke was utilised for compositing with Arnold for rendering: “We did have digital matte paint artists to help us with some of the backgrounds in the other shots,” says Ivan Moran. “Maya is our package for 3D but it’s heavily based on our own toolsets.”