How Realise ‘cracked the track’ for a roller coaster ride

When Carlsberg wanted to announce that it was sponsoring the English Premier League, it chose to do so in epic style – by featuring members of the football fraternity on an ‘endless’ roller coaster ride, designed to showcase the wide emotions of the game. Having so many people and multiple coaster cars might seem like a spot suitable for CG. But Realise Studio, led by visual effects supervisors Jordi Bares and Ally Burnett, turned to a combination of both practical and digital means – plus a clever approach to tracking – to make ‘The Ride’ a reality.

Director Juan Cabral suggested that the spot be achieved ‘in camera’ as much possible. “We took this literally,” says Jordi Bares, “and really wanted to crack it even though it was obviously impossible to put that many carriages together in real life. We decided to avoid at all costs shooting a roller coaster on a stage. This would look too post-y and destroy what Juan wanted to achieve, so we did a huge amount or research and tests to prove there was a better solution.”

That research involved a technical recce of the roller coaster in the Netherlands – known as Goliath – a 64 meter high ride running at speeds of more than 120km/hr. “I even managed to go on the ride to get a real feel for it…agonizing…there were truly some scary points and replicating those sensations is something I really wanted to get on screen,” notes Bares.

Realise Studio's Jordi Bares atop the roller coaster.
Realise Studio’s Jordi Bares atop the roller coaster.

Ultimately, the kinds of shots required and how they would be accomplished for the spot broke down into four categories, as Bares describes:

1. Exterior shots (shots from outside the roller coaster looking at the carriages) with a multi-pass approach using static cameras

2. Exterior helicopter shots with CG trains

3. Interior shots looking to the front where the camera is actually mounted on the coaster. We had an incredible grip department to do this

4. Interior shots looking back (to look at the faces) and, where we needed to, extensions of the train which was obviously the biggest challenge, a full CG train behind the live action one

An ARRI Alexa is rigged to the train.
An ARRI Alexa is rigged to the train.

Photographic survey of the coaster became the central source of data that Realise relied on to execute the spot, especially to help with tracking. Bares says he tried to obtain CAD data and that, in hindsight, a LIDAR scan “would have been very helpful, but of course the limitations of the space range to be covered would have been problematic, the ride goes up 65 meters and takes 1.5 minutes to complete so you can imagine at speeds of up to 120km/h the ride is truly huge.”

“We also tried to get the model track from a website of aficionados that love roller coasters,” adds Bares. “Someone has taken the time to model it for simulation software in a virtual ride. This did allow me to navigate through the intricacies of the shots and work out where the pitfalls would be. I managed to get this geometry inside Houdini but rapidly realized it was not very accurate so discarded it as a guide to our tracking.”

Survey measurements for the train car.
Survey measurements for the train car.

In shooting the live action components of ‘The Ride’, the team wanted to maintain the high speed and high vibration feel of roller coasters, something Bares had observed by taking the ride himself. But this also meant that acquiring the footage – using a combination of ARRI Alexa, RED EPIC and GoPro cameras – would include, by default, high speed and vibration artifacts. Bares was adamant, then, that tracking was the issue that would “make or break the job.”

While planning the shoot, the team had a ‘tracking breakthrough’. “Ally had a simple idea that was the trigger to the breakthrough, to track the whole thing,” recalls Bares. “The breakthrough was based on the assumption that the track never moves and the train always goes at the same speed (approximately), and together we devised that if we managed to track the camera once for the whole roller coaster we never had to track again, just rotate the camera, line up and match the speed given certain shots were at 120 fps and others at 50 fps.”

Watch the master shot from the forward facing Alexa.

So Realise chose to track the roller coaster just once using a front facing camera. “We assumed the train travels through the rails exactly in the same position every single time,” explains Bares, “at the same speed and that there are no vibrations. The result is the ‘heart line’ and this could be generated looking forward rather than backwards. If we tracked the whole ride, it should end exactly in the same place as it started and THAT will be our validation point.”

Photography of the area would be used for reference when tracking, as would helicopter shots. The team also laid down a large number of ping pong and tennis balls on the rails. These were used to create a master pass with the ARRI Alexa looking forward. As Bares explains, it was “shot at 120 fps to maximize the sampling and make sure the tracking software could deal with it. Funnily enough, 18,000 frames is something no tracking software was happy with and we tried quite a few options. After revisiting the approach we broke it up by segments that could be validated. For example, the big roundabout that is used a few times goes under the bridge where the roundabout starts, so that is our validation point.”

Watch a portion of the matchmove of the master shot.

From the ‘heart line’, Realise created the rails of the ride. “These were used for layout of the track and then we could find visually were the real camera looking back was positioned,” says Bares. “With the help of a simple tool we built, we applied camera speed compensation – some shots were shot at 50 fps, others at 120 et cetera – and after that we would do a simple test to check if we were in the right place. This actually was really not that obvious!”

It was a tough two days shoot (plus a test day to check the rigs) that had to fit in with the daily schedule of the working roller coaster. The team would begin shooting at 5am until 10am, then the ride was open to the public until the park closed at 5pm and shooting could continue until 10pm. Meanwhile, data would be sent to artists back at Realise’s studio so that they could begin on tracking, modeling, textures and CG work.

The two-camera set-up for the wide panorama.
The two-camera set-up for the wide panorama.

Realise recruited an expert tracking artist, Simon Payne, who ‘cracked the track’ in segments using Boujou. “It took almost 3 weeks but in the end we did it,” says Bares. “We had a track that was fully validated. On many occasions I had to work with the team on some of the line ups because I simply got to know the roller coaster so well and in the end could quickly decipher where the camera was.”

Wide shots came together via stitched panoramas shot with two Alexas. The stitched shots were later used either as a large locked panorama or paned inside the stitched image as if a camera was following the action. “This was then repeated for up to 25 takes with different carriages that enabled the Flame and Nuke team to assemble some epic moving wide shots,” outlines Bares.

Watch a test of the panorama stitch.

“Obviously,” adds Bares, “there was a huge amount of roto involved – yep, by hand – and stitching together the carriages which took a bit of time as we didn’t want to make them run at the same speed all the time in a neutral way, so we had to time warp every single carriage. In Flame these render times were pretty scary but the truth is that it was really nice technique as we could easily swap carriages and construct the correct layout that would represent all the teams in the Premier League.”

The wide shots also feature digitally animated characters, elements that relied on iPi Soft’s motion capture tracking system with a Microsoft Kinect. “Our producer Paul was my actor,” says Bares, “and we produced five different clips of 2000 frames each that looked great. Also we added flags which was clearly critical and scarfs too.”

A still from the spot shows the GoPro footage and the digital work behind.
A still from the spot shows the GoPro footage and the digital work behind.

Additional work include sky replacements, the 3D football and the Carlsberg sign which was created procedurally in Houdini to allow for flexibility in different shots.Bares says the most challenging aspects of the spot were GoPro shots that were included in the edit but not initially planned to be digital extensions. “They were only for face reactions, but in the edit they worked so incredibly well they had to be used,” Bares notes. “Once again we took it as a personal challenge and cracked them using the technique I mentioned before, although we had to pre-process (in Nuke) all the GoPro footage to remove the wobble/jello effect of rolling shutter. We then added our CG and at the end reintroduced a bit of the GoPro jiggle effect that gave the amazing emotional effect.”

“I can safely say I have been waiting years for a job like this to appear on the radar,” says Bares, reflecting on the project. “Needless to say when we were awarded the job we were literally over the moon and we put all our love into it which hopefully is visible.”

A final shot showing the added Carlsberg sign.
A final shot showing the added Carlsberg sign.


Agency: Santo
Client: Carlsberg
Production House: MJZ
Director: Juan Cabral
Service Company: Bonkers Amsterdam
Postproduction: Realise Studio