In 'Nocturnal Migration', a Tooheys Extra Dry spot for agency BMF Sydney, director Garth Davis of Exit Films called on Alt.vfx to help create a gathering of city-dwelling deer having a night on the town. We talk to Alt visual effects supervisor Colin Renshaw about mo-capping real animals, adapting to the needs of the spot, and making deer party.

- Above: watch the final spot which features the tune 'Breathe' by The Prodigy.

How to capture deer

The spot was one of the first through the door for the brand new Brisbane studio. "We had literally just started the company," says Renshaw. "When we were pitching and quoting the job, we actually didn't have a single computer - none of our gear had arrived yet and we were formulating our set-up. But when we were awarded the work that actually influenced the way we approached the spot and the pipeline here a lot."

Before any effects work would be carried out, however, Renshaw, and Alt.vfx executive producer Takeshi Takada found themselves an integral part of how 'Nocturnal Migration' - which was to follow a herd of deer through the streets of Auckland, to a disco, a house party and into the morning sunrise - would be filmed. "Garth's approach is always to try and do as much as he can in camera," says Renshaw. "So originally we were only going to play a very small role in the sense that we were going to do almost crowd replication, with background deer to fill out the street. But we soon realized that the deer were not going to be able to do everything we wanted them to do. They were great when they were just standing doing nothing, but if we wanted them to go from A to B, it became more difficult."


- Above: watch a breakdown of the visual effects work by Alt.vfx.

An early test was orchestrated to produce a photorealistic 3D deer, based on reference shot in New Zealand and modeling, animating and compositing by the Alt.vfx team. "I turned up at the pre-pro with a shot we'd filmed out at the car park of me feeding a deer with my hand, which they really loved," recalls Renshaw. "In the meantime, we'd also made an internal decision at Alt that we were going to use motion capture for this spot, and so we organised some deer trainers out of Melbourne and did some mocap with them through Deakin University."

Here, at the Deakin Motion.Lab, 78 tracking balls were applied to live deer with cattle glue and the deer's performance captured by around 24 infra-red cameras. "We went down the mocap route," notes Renshaw, "because even though our test was hand keyframe animated, we had seen some cool mocap of horses and thought it was such high fidelity and had some fine nuances that we thought we would never be able to animate. We actually took that mocap data and applied that to our deer - it looked awesome but too horse-y. And we couldn't find any deer mocap anywhere - there was some but it was a little lumpy. The deer must have been 100 years old!"

Click here to see the Deakin Motion.Lab behind the scenes video from the deer mocap session.

On the mocap stage, Renshaw's team utilized a live solve of the capture data onto their deer mesh to check rough performances and camera moves. Ultimately, Autodesk's MotionBuilder and Maya were used to clean-up and carry out final animation of the digital deer. Having the original successful test and the mocap data convinced the director, too, that more elaborate shots could be composed for the adventurous spot. "It actually gave them freedom to literally just grab a camera and start walking around the city and shoot things without having to drag a massive production with us," says Renshaw. "A lot of the best shots were purely that - with Garth and the DoP, the 1st AD and myself and the producer - just walking across intersections. It was really off-the-cuff stuff."

Deer need fences

In Auckland, 14 trained deer were used on set to film many of the planned shots. The production shot mostly on the ARRI Alexa, with a two metre high fence surrounding the shooting locations. "There were some really great deer performances," says Renshaw, "and then others where we thought it would be super-simple but the deer just didn't do it. I covered off myself with clean plates and camera moves, sans deer, so we had an option."

"It would also give Garth freedom to go to his edit with in-camera stuff," adds Renshaw, "plus it was also great lighting ref for me as well. And I would also get HDRIs and survey data for every set-up regardless of whether we were going to do CG deer or not."

Aerial scenes were filmed via helicopter on long lenses without the benefit of significant survey data for tracking. Massive and V-ray would later be used to produce the herds of deer in those shots. At street level, the visual effects team relied on eight practical 'mules' as reference for the digital deer. "They were green boxes built to the proportions of between a male and female deer," explains Renshaw. "We dragged those around Auckland - they weren't very light - but they were a great help with scale and aligning the camera, especially for working out where the ground plane was with the style of shooting. I also draped a deer fur over one of them as an additional cue for the lighters."

Adding Alt's digital deer

Back at Alt.vfx, artists immediately began blocking out scenes based on a rough cut from editorial. "We literally did slash comps off the ProRes with massive handles just to give editorial plenty of headroom either way," says Renshaw. "The first part of that involved throwing in a deer mesh, in a T-pose almost, just to get a sense of numbers. At the same time that was happening, we were already doing roto on the real deer and on cars and other objects in the scenes."

The layout phase was also greatly aided by an extensive library of mocap animation that had been amassed earlier. "We categorized the deer performances as a whole bunch of things - milling around, head turns and standing and moving," says Renshaw. "I could very quickly sit with an artist and lay out a scene with a hundred deer or more. On top of that there were certain performances Garth really wanted, and we would just use a new animation layer in Maya and animate over the top. We'd have to do hand animated cycles where the speed of the deer wasn't enough, or the gait wasn't right for what we needed, such as where they run around the corner."


- Above: watch a behind the scene featurette on how the deer were filmed in Auckland.

Alt.vfx used PFTrack for tracking and Nuke and Flame for compositing. Some of the particular comp'ing challenges lay in matching to the hand-held camera feel and hazy, nighttime atmosphere. In one scene, in which the deer gather at a disco, much of the ambient light was captured in camera and then replicated in other shots by Alt.vfx. "We had to replicate the warmth Garth was after and the mood," comments Renshaw. "A lot of that came from adding layers and atmospherics."

Many of the live male deer were augmented with digital antlers, seeing as the real thing could have been lethal. This effect was achieved both as a 3D add-on or via a 2D comp. "I shot a lot of antler plates while I was there on the last day of the shoot," says Renshaw. "We made up these 'horn-helmets', which were basically antlers stuck on bike helmets, and then we just went through a bunch of slow turns and moves. There were a few we had to object track as 3D, but for a lot of them in the disco it was 2D."

Another challenge for compositing came in the form of a shot of the deer walking through a park. This was originally filmed in an Auckland suburb, but Alt.vfx replaced the original background with images of an apartment tower and trees sourced online. "They really wanted to get a bigger feel," says Renshaw. "We pulled that shot apart, roto'd the deer completely, and re-built the background in Nuke using projections with a few iterations and then added flaring and haze."

The visual effects work continued right up until the end of a tight four week schedule, as Alt.vfx refined its use of Shave and a Haircut and 3delight to realize the deer fur. In particular, a hero shot of a dancing deer received additional detail via modeling in Mudbox right before the deadline. Ultimately, the studio's core team of ten swelled to 15 over the production to produce a total of 48 effects shots in the 60 second spot.

"I think the beauty in the spot comes down to the way Garth likes to work," concludes Renshaw. "It's all about happy little accidents and found moments. In fact, I think my favorite two shots are the street-crossing ones at the beginning. That was Garth saying, 'Hey, wouldn't it be cool if…', and then he just ran off with a camera and I followed behind with this sick feeling thinking how the hell are we going to do this? At the end of the day, those shots just look nuts."

Alt.vfx credit list

VFX Supervisor: Colin Renshaw
Executive Producer: Takeshi Takada
3D Supervisor Fur TD: Nick angus
2D Supervisor: Matt Chance
Flame Artist: Urs Furrer
3D Artists: Sarah Collier, Chris Rentoul and Massimo Righi
Crowd TDs: Malcolm Wright and Nigel Haslam
Compositors: Tim Walker and Chris Elsom
Matte Painter: David Woodland
Motion Capture: Deakin Motion. lab
Colourist: Warren Eagles


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