SyFlex in Harry Potter and the Goblet of Fire



Feature Film


Client: Warner Brothers
VFX Studio: Double Negative
Released: November 2005
Visual Effects Supervisor: Mark Michaels
CG supervisor: Richard Clarke
VFX producer: Dominic Sidoli
Deatheater sequence supervisor: Ged Wright
Portkey sequence supervisor: Ryan Cook
Lead digital double TD: David Vickery
Senior TD: Hege Berg
TD: Dan Wood
TD: James Lewis
TD: Ummi Gudjonsson
TD: Dameon Boyle


Double Negative in London used SyFlex in 13 digital stunt double shots they made for Harry Potter and the Goblet of Fire. Death Eaters, good wizards, baby lord Voldemort, as well as the hero kids, all enjoyed SyFlex clothes when needed. The Moving Picture Company also used SyFlex for Voldermort's cloak, and Framestore CFC used it for the kids' clothes in the underwater scene.


We spoke with Lead Digital Double TD David Vickery from Double Negative, who gave us quite a bit of details about the work they did with SyFlex:

Syflex: Where in the film can your SyFlex work be spotted?

David: We used SyFlex in three sequences: the Graveyard, Dark Mark (ministry of magic wizard apparition), and the Portkey.

There were 4 deatheater shots in the graveyard sequence and in total we created 7 deatheater digital doubles that had to be able to be seen very close up on screen. We had the task of creating the deatheater apparation effect. The Death Eaters were to arrive from the sky amongst an amorphous spear of smoke, stabbing into the ground and suddenly taking form amongst tendrils of this acrid black smoke. The black smoke needed to encircle the Death Eaters bodies, becoming the black of their swirling cloaks as they materialized.

The costumes of the Death Eaters were modelled from clothing patterns supplied by the art department, textured and then simulated using SyFlex. The resulting cloth simulations were used to help drive fluid simulations for the black smoke. The cloth simulations were lit and rendered using in house BRDF shaders, developed for Batman Begins, along with sub surface scattering for the skin areas. In most cases the Death Eaters and their cloth simulations were so convincing that we were able to use the CG stunt doubles for the full length of the shot, rather than having to complete a tricky transition back to the actor/s themselves.

In the Dark Mark sequence, the effect we had to create here was very similar to the deatheater apparition. These wizards were 'good' so there needed to be differences in the way the effect played out. SyFlex was used to generate cloth simulations for the wizards as they appeared. This was then used to help drive the smoke that swirls around the actors as they materialize.

In the portkey journey that took Ron, Harry and Hermione and the other kids to the quiditch world cup, there were 3 shots that used digital doubles realized using SyFlex cloth simulations. We created 9 digital doubles for this. The sequence required moments where the characters would be required to go beyond the physical limitations of the green screen wire work acrobatics that they had performed. It was assumed that digital doubles would need to take over. Each character body was modeled from cyberscan data. Clothing was hung on the character and cloth simulations run to ensure that each piece of clothing behaved as expected in extremely windy conditions. Once the texturing and shading had been completed, the digital doubles were animated to extend the performance of the green screen wire work performed by the actors.

In the Graveyard sequence we also had to create some extra cloth to cover the legs of the lord voldemort baby figure, matching the existing cloth that covered to rest of the puppet.

Syflex: You worked mostly on the Death Eaters... Can you tell us what were the director's requirements here?

David: The Death Eaters had to be dark and scary with a really sinister quality to their apparition effect. It needed to look like an 'amoprhous spear of smoke' stabbing into the ground, with a certain level of supernatural control to the smoke as it swirled around the materializing digital double. The director had shot plates of the deatheater actors as he imagined they would step forward out of the smoke at the end of their apparition, so we knew we could create a transition from a digital double to the real actor if we had to. The problem with this was the takeover point from one to the other - matching the exact position of a digital double to the actor at any particular point would have been very time consuming. In the end the cloth simulation and final render of the Death Eaters was so convincing that in a number of the shots we kept the digital double in the shot and left the actor out altogether.

Syflex: What was the most complicated shot/effect?

David: The most complicated shot was probably the wide high shot of the Death Eaters apparition around lord voldemort. In the end we only had 4 Death Eaters, all of which ended up as digital doubles throughout the whole shot. Initially we had as many as 7 Death Eaters in the scene, each of them with 5 pieces of clothing that we had to run cloth simulations for. It would have been extremely hard to get a single simulation that got the cloth right for each of the Death Eaters. In the end we simulated each piece of clothing separately, multiple times, building the scene up and re-simulating the cloth so that each article of clothing collided correctly with its neighbors. Using the SyFlex cache tools allowed us to paint out areas of clothes where the simulation wasn't behaving and use another iteration of the sim to fix it.

We knew that the cloth sim would have to be absolutely perfect, because it was used to help drive the fluid simulations of the deatheater smoke as well as for the final beauty render of the digital double.

Syflex: What made you choose to work with SyFlex?

David: Having used SyFlex for a number of years now, I have a pretty good idea of its benefits and limitations. In my opinion its a lot faster than Maya Cloth, and produces excellent results.

The support is excellent. I always get quick replies to any queries I may have with new features or potential bugs, so I also feel like I have a good contact when I get stuck!

Syflex: Which other projects did you use it in? Any upcoming projects you can tell us about?

David: I have personally used SyFlex on The chronicles of Riddick (Judy Dench's Aereon character), Batman Begins (digital double for Batman) and the Goblet of Fire. We are using SyFlex at the moment on a number of shows, but I am unable to disclose the exact nature of the project I'm afraid : )

Syflex: Anything else you would like to share with us about your working experience with SyFlex?

David: SyFlex is a very intuitive piece of software, I had never used cloth software before I came across SyFlex but it took me no time at all to get to grips with it. The main thing for me is that there is a huge degree of flexibility in what you can achieve with SyFlex and like I said earlier, if you get stuck, the support is very quick to try and help you out!


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