Thu 6th Mar 2014, by Paul Hellard | Production
All Images Courtesy of Warner Bros. Pictures.
Australia’s Animal Logic, with Warner Bros., Village Roadshow and Lin Pictures joined together to produce The LEGO® Movie, the first-ever feature-length LEGO® production. The film is the story of an ordinary LEGO minifigure named Emmett, mistakenly thought to be the extraordinary Master Builder. His ill-found quest is to stop an evil LEGO tyrant from gluing the universe together. Animal Logic's crew of more than 350 artists, developers and technicians spent over two years on the production, coinciding with production on Walking with Dinosaurs 3D and The Great Gatsby.
Legendary Animation Director, Rob Coleman was considering leaving Australia and going back to Los Angeles when Animal Logic CEO Zareh Nalbandian called him after hearing the rumour going around. He said, ‘No, you can’t leave Sydney. Come over and I’ll show you something we’re developing here’, says Rob. ‘He showed me the test for LEGO and I was completely blown away.’ Not long after that meeting Coleman was brought on as Head of Animation at Animal Logic.
When the writer/directors Phil Lord and Christopher Miller came to Animal Logic in Sydney, they spoke to the team about the opportunity to create the biggest brick film ever made. They were adamant they needed to stay true to the LEGO brick toys. That meant the mini-figurines needed to keep to their true form and their movements needed to remain authentic. Animal Logic was going to make it completely convincingly real in 100% CG. No pressure.
At the outset, there was a requirement of developing a good knowledge and physical understanding of the LEGO product itself. “We wanted to make this film feel authentic in its CG-stop motion, so we took a quite literal approach to the project,” says Animal Logic CG Supervisor, Damien Gray. “This was approached from a physical build standpoint. There was a program of becoming familiar with the bricks themselves and the different types and how they snap together. The language of LEGO from a design standpoint helped us understand how they translated into CG. This was seen as the best place to start. Being a product that has been around for so long, a lot of people do already have a familiarity for the product.”
Animal Logic studied a lot of macro-photography and set upon using a very shallow depth of field wherever they could. “We created a camera rig like a virtual steadicam operator but at the scale of the ‘minifigs’,” explains Gray. “The inspiration was mentioned by the directors again and again. YouTube is filled to the brim with stop motion of real LEGO figurines. The brief was to take that and scale it up to feature quality, without shying away from the ‘rough edges’ and their filming technique. Instead they wanted us to embrace that,” Gray says.
Lining up and blocking a shot required a clearer view of all the assets so the DOF effect could be switched off and on at will, which gave the artists a very quick way to decide where the focus needed to be, particularly when a character might lunge forward toward the lens. “It was very helpful for us to be able to do that on the fly,” adds Gray.
The LEGO Group in Denmark was a very important partner in the creation of the assets in The LEGO Movie. “The LEGO team visited Animal Logic from time to time and it was pretty clear to them that something pretty amazing was being made,” says Rob Coleman. “Both creatively, and for the product. I saw them at the premiere and there were big smiles on their faces.”
As well as bringing a crate-load of LEGO packs into the studio for early familiarisation sessions, the company also referred to their app. The free downloadable LEGO Digital Designer application helped the artists build the digital models onscreen, and gather assets with the signed-off correct number of real blocks, ready to go into asset building for the actual production. “We had a good look at a lot of options at the beginning of the production and we saw an open source piece of software called ‘L-Draw’ but in the end we went with LDD because it had all the functionality we might want, but also the fact that the file format was compatible for a direct export to Maya,” says Gray.
The files output by LDD are basically XML. “Each brick has a 3 to 5 digit ID number and a part list,” Gray explains. “We had a piece of software that helps us build LEGO-legal models, and a part list at the end of it. At Animal Logic, we’re used to breaking our assets down into very small parts. Across Maya and XSI, we break down our geometry, rig-defs, UVs into separate files, and here were the assets all set up perfectly so we could begin the brick-building stage. This gave us a speed boost to ratchet up the geometric complexity.”
The biggest asset in LEGO was a large background building in Old Town that reportedly had over 5,000 bricks in it. At one point a human hand appears, a massive rainbow, basically a lot of geometry that would be redundant in a more traditional pipeline. “We took the opportunity when we were baking the geometry into the shells, to delete the top of one brick when it is obscured by another, for instance,” says Gray. “So we could offload a lot of the geometric complexity in some scenes, except for when the buildings were needing to be blown up and the studs would have to reappear along the way.”
Looking at the challenges ahead, the Lighting Supervisor, Craig Welsh thought it would be easier than it turned out to be. Plastic was the industry default surface after all. But this plastic was reflective, refractive, semi transparent, and had a lot of exposure to the elements. “That became the biggest challenge, which multiplied before our eyes,” says Welsh. “Subsurface Scattering has been around for a long time, but only on ears and heads of characters. We had to run SSS through everything in the scenes.”
“If you have the budget and the crew you can spend time breaking down shots into multiple layers and that’s a very labor-intensive process but we needed a more automated way of working through that geometry in a few passes as opposed to dozens of passes,” explains Welsh.
Water, fire and smoke were all tackled using bricks. The directors Phil Lord and Christopher Miller wanted to go down that road from the beginning, with a nod to those low-budget stop-motion videos bringing in a bit of charm. In Houdini, the FX crew would build particle clouds and brick summoners. Each particle in the cloud would have an ID, which represented a brick carrying a full description with color, size and opacity, and SSS detail if needed, built into the walls as well.
“There were some massive assets built for the production. We’d done this scale before. There’s a Wild West sequence where they run through a canyon and we’d modelled all the sides of the canyon, then filled it with bricks,” adds Gray. “It became a ‘geometry and complexity’ versus ‘render times’ argument.”
While Animal Logic only created LEGO assets that could be created with the bricks in reality, the Sydney studio could play with scale. While it is possible to build a car out of 5,000 bricks, it is also possible to build a very much smaller version of that same car, out of five bricks. A sweet visual gag is shown in The LEGO Movie wherein a scene with a lot of action, lots of models and they cut wide to a three brick version of that same action seen from a distance. “We created several gags along those scale themes throughout the movie,” says Gray.
There are parodies of movies like The Matrix, and that stop frame animation rate of two and sometimes four frames for each shot, which accentuates the snappy stop-motion style of early animation.
Because the style was leaning towards the real stop-motion look, Animal didn’t do what a lot of LEGO animation had done in the past, which is bending knees, elbows and torsos, instead keeping everything quite rigid. The Animation Director Chris McKay had a lot of expertise in bringing more life out of a LEGO mini figurine using some BluTack and a nail file. A lot of freedom was given to the CG joints between parts in some shots, and that allowed more dramatic/comedic license.
Replacing motion-blur behind a fast moving character was a trick called brick-blur, a small ledge of bricks trailing behind. Another gag is when a character is hit or punch, a little fairy wand appears, all part of the real LEGO props used inventively throughout the movie. “Looking through LDD and the catalogs, the artists found all kinds of extraneous items that could be used to represent action by just flashing on and off,” says Rob Coleman. “The FX group did an amazing job of prepping all of these stud bricks, both opaque and transparent, dissipating to nothing.”
The biggest increase to render times came from the approach to lighting, shading and rendering in general. It was physically-based shading and each brick had a list of standardized maps that would define the subtle warping of its faces. “No brick was completely rigid or flat. Everything had to have a bit of a lean to it, a bit of warping, to get the realism,” says Gray. “There were mould line maps, decal maps, all kinds of weathered texture maps with every brick. Finger prints as well. There were also a lot of procedural effects like some oxidisation on some bricks. Every brick had a bit of a knic taken out of it. If you left your LEGO out in the backyard, you’d get that peeling, whitening and discoloration to the plastic. We baked out occlusion maps, fed that back into the shader and allowed a procedural amount of oxidization. There’d also be what became known as ‘grunge’ where an inverse occlusion map was fed back into the mix. That was for bricks that had really had a hard time in the Wild West scenes of The LEGO Movie.”
Pixar RenderMan was the primary renderer on The LEGO Movie, but it had a bit of help. One of the top Technical Directors at Animal Logic, Max Liani, writes ray-tracing renderers as a hobby, and one day he showed Craig Welsh what he’d been doing on the weekend. “He’d rendered a massive cube out of millions of triceratops from the ‘Walking with Dinosaurs’ assets,” says Welsh. “Looking at the stats of how quickly it had rendered, it became clear he was onto something. He’d developed his own raytracing accelerator that he called Glimpse. Max Liani and Luke Emrose suggested we use Glimpse as a raytracer before PRMan. In the old school days, when PRMan didn’t do ray tracing, Larry Gritz had written Blue Moon Render Tools (BMRT), which helped PRMan handle reflection calculations.”
With a Ptex workflow, the secondary rays didn’t support distributed textures like fingerprints and stickers that spanned across several bricks. So, Liani and Emrose would make Glimpse handle all the secondary SSS bounces, then feed them back into PRMan. While there were some workarounds required, by the end of the production they were rendering everything completely out of Glimpse, handling ray-tracing SSS with millions of polygons. Max Liani’s ideas were tested, proven and adopted at just the right time to save the production an incredible slab of power and time and he delivered the solution in perfect time. “Boy, did he deliver! Everything was awesome!”
All Images Courtesy of Warner Bros. Pictures..