How Weta’s VFX Team Plotted the Scenes for ‘Mulan’

“Mulan” lands on Disney Plus for subscribers at no extra charge this weekend. The live-action remake directed by Niki Caro is an adaptation of Disney’s 1998 animated film and based on Chinese folklore. The film stars Yifei Li as Mulan.

Weta Digital crafted hundreds of visual effects shots to reinforce the authenticity of the film’s settings and spectacular action to make the movie immersive and resonant. Their VFX shots spanned ancient China, and a key location is the Imperial City — fictional environments based on historical places and design principles, and the VFX house delivered the majority of the visual effects shots required for the movie, completing 434 shots in total.

Having begun working on the film in the summer of 2018, the Weta team went to China collecting the necessary shots before principal filming had even began, so much of their work was guesswork on what Caro would need.

From building the Imperial City in Houdini, to rendering the images in Manuka, the Weta team were able to recreate what they needed with ease.

VFX supervisor Anders Langlands and digital compostior Beck Veitch break down the art of VFX for  “Mulan.”

Anders Langlands on Recreating the Imperial City

We first got involved in the project in 2018. Aside from the costumes, we started looking at the Imperial City. We began by looking at the concept art by production designer Grant Major and starting to think about what was the best way of putting it together.

We went to a backlot in the Hubei Province in China, shooting there with the second unit. We knew we needed to be getting a lot of material for that which would then be used for the main shoot in Auckland.

We did the largest LIDAR scan we had ever done for a movie. We scanned it in 3D taking a lot of photos, concentrating on areas where we knew a lot of action was going to take place. What was great about scanning the whole studio was that it gave us the source material for then building hundreds and thousands of buildings that would then be needed to create a city.

We need we would need to create a very detailed CG build of those portions of the backlot location that would be featured and those were extended to create the wider environment.

For research, we looked at historical maps of the city to establish the size and shape. The city was laid out on a three-by-three grid with huge avenues dividing each of the districts. I think we ended up squeezing it down a little bit because it looked impractical.

We had looked at individual plots and where high-ranking officials were living because that was available. We looked at where monasteries were and marketplaces. So we built-in rules to figure out what areas of the cities were wealthy districts. Those areas had larger plots of land and the buildings were grander and bigger.

It was about the same land area as Manhattan. This system allowed us to procedurally generate the city inside a computer by creating a few rules using Houdini.

Once that was fed into our layout system which would look at the ruleset, and it would populate the entire city without someone having to go in and model every single building by hand which would have taken a lot of time.

That was important creatively because we could just make huge sweeping changes without someone losing their mind every time you wanted to change the terrain.

Beck Veitch on the Witch’s Transformation

It was a challenging shot to put together because the brief was to change the soldier into the witch with her sleeve as a wipe. We thought we could do it. But then that went away and they wanted to see it as a transformation.

Gong Li plays sorceress named Xianniang. In the sequence, she leaves the Emperor’s palace disguised as a soldier, and in the end, we ended up using three plates for that sequence.

The witch walking was played by Yaxi (Liu). The first pass was her walking without the green screen. Then we had her walking along with a clean plate, and again on a clean plate. And that would drive the entire transformation.

A clean plate is part of any VFX kit. The idea is if you’re replacing a performer in a scene with a CG version of them or replacing a surface, you can shoot a place without anyone in it with the exact same camera move, and that gives you source material to remove anything from the hero plate.

So, we had the soldier plate, the witch plate and the clean plate. We rebuilt the background, extracted the solider and witch from their plats and synced them up. Next, we created digital versions of the witch and the soldier, and the hawk that you see was fully digital, and it was all blended through the photographic plates to make that appear smooth.

The challenge was in matching some of the bits up especially with the walks since men walk differently. So, we took the plates and retimed them to match and have matching physics. If you look at the soldier, he’s wearing big clunky boots and is a different shape. Whereas she is so delicate.

It was a subtle effect because you don’t realize what you’re seeing until it had happened. That shot is one of the big transformation shots that we see for the witch.

It was nice to do something to hide what you’re doing rather than have it be a big showy effect.


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