Lighting the LEGO Movie

Animal Logic pieces together a process for lighting and rendering the scenes in The LEGO Movie.

LEGO superheroes, wizards, and the Millenium Falcon coming to life on the big screen? Yes, please! The LEGO Movie opened on February 7, 2014 and has surpassed $200 million at the box office. This hilarious tale is a stunning achievement in animation and visual effects by the folks at Animal Logic. Barbara Robertson went behind the scenes at Animal Logic to interview their VFX team on their lighting and rendering process.

See a story on the movie's design at http://www.cgw.com/Press-Center/In-Focus/2014/LEGO-Land.aspx

Usually when we think of digital doubles, we imagine stand-ins for actors in live-action films, and consider the challenges of creating photorealistic CG humans. And when we think of digital environments, we imagine photorealistic landscapes and set extensions. It comes as a surprise, then, to realize that Craig Welsh of Animal Logic, the lighting supervisor on Warner Bros' The LEGO Movie, faced many of the same challenges, as would a CG lighting artist working on a live-action film.

Everyone knows what LEGO bricks look like. It was up to the texture, shading, and lighting artists to match that reality and bring alive the miniature characters and sets in a photorealistic world. Prior to this film, Welsh was a lighting artist on The Matrix Reloaded, Shrek 2, Madagascar, Monster House, Surf's Up , I Am Legend , Speed Racer, and Lighting Supervisor on Legend of the Guardians. For The LEGO Movie, his crew of 45 included three lighting leads, a handful of compositors, and six technical directors who wrote tools and supported the artists. Two of the TDs, Max Liani and Luke Emrose, developed Glimpse, a custom renderer.

Images courtesy Warner Bros. Pictures

If you want to match a LEGO brick, think beyond a plastic CG surface.

We used only legal LEGO colors, and emulated the plastic material with the correct diffusion and colors, Welsh says. LEGO plastic scatters light through it, so you need to do a lot of ray-traced calculations to get subsurface scattering. And, every surface in the LEGO world is highly or somewhat reflective, so you need reflections and refractions. You have to pay a lot of attention to oxidation of the bricks, particularly for the exterior shots, as if they had been in the sun and the weather, or maybe in a sand box. And for the interiors, as if they had been in a basement for 10 years. You have to add fingerprints, thumbprints, make them look sticky with dust and hair. And, you have to do that efficiently. We used ptex to distribute thumbprints across multiple bricks.

To design photorealistic lighting, start with something real.

We had a lot of concept art and a lot of LEGO in the building, Welsh says. People in the art department were modeling with the LEGO. So, we took photographs of the buildings and experimented with depth of field. To get a photorealistically convincing look, you have to underpin it with the concept of how lighting really works. We carried boards with LEGO-built streets outside and photographed them in the sun. We took HDR probes of the environments to replicate them in the computer and played around with different settings for the HDR maps. We considered how to make the cylinder heads look appealing. How to give them shape and convey emotion with lighting. We did it again and again until we got it right.

When you're making a film, reference interesting lighting from previous films.

The first sequence I got my teeth into in terms of look was the interrogation room with Emmett and the bad cop, Welsh says. I created it with real LEGO bricks and talked with [production designer] Grant Freckelton about how to approach the lighting. He suggested looking at the interrogation scene in The Rock. I racked my mind to think of others and a scene from Basic Instinct stood out because of the striking lighting coming down through a grate. I looked for LEGO pieces I could use, and found one with a grating pattern. I put an LED bulb behind the grating and got a nice effect, so I photographed it from different angles and exposures. After Grant and I talked about what was visually appealing and what made it seem real, I went to town with the [digital] light rig. I made a gray-scale image in the shape of the grate and made a gobo out of that. Then we went back and forth with the renderer until we got the look.

We also had reference images and other examples of real world cinematography, he says. We'd emulate the way Michael Bay lights street scenes.

If you spend time developing your visual language, you won't panic if the story departs from the color script.

Grant Freckelton and the art department developed a color script for the first two editing sections of the film, and the goal was to have scripts for the rest, but the story changed, Welsh says. We knew the general story arc, the time of day at various points, and the emotional content. So, we pretty much did on the fly' key lighting. It sounds ad hoc, but it wasn't because we had done so many explorations. We could leverage those early conversations.

Don't be afraid to depart from reality if that works better to achieve your goal.

We always tried to imagine how a scene with actual LEGO pieces might be lit and tried to stick to that as much as possible, Welsh says. We'd ask ourselves how can we make this wonderful thing, this model, look fantastic, as if it were built in the basement and lit by a whiz bang miniature photographer.

But, if we really put a lipstick camera into a set built with LEGO and photographed it, the depth of field would be so shallow the backgrounds would be a blur. We had an enormous amount of detail in the background that we didn't want people to miss. We tried to keep the sense of a miniature envir

LINK:	http://www.cgw.com/Press-Center/In-Focus/2014/Lighting-the-LEGO-Movie....
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