The Mill makes Audi hum

In Audi’s A6 Avant ‘Hummingbird’, directed by Daniel Barber for BBH, a mechanical bird ventures along a surreal country road. The flighty hummingbird – intended to echo the Avant’s lightweight construction – and the roadside-inspired environments were created by The Mill. We talk to four key members of The Mill’s visual effects team to find out how they designed, modeled, animated and composited the final spot.

fxg: Can you talk about how the characters in this spot were designed?

Tom Bussell (3D lead artist): We were involved from the very early stage of the project. We put a team of artists together to come up with some concept stills that followed the script and director’s treatment whilst also maintaining the visual brand of Audi. These images then became the benchmark for the entire project. The hummingbird and other characters were approved as 2D concepts before modeling started in 3D. This meant we could show variations quickly and finesse the designs without wasting time making alterations in 3D.

fxg: What was involved in modeling the CG assets?

Bussell: A few artists took a camera and tripod around the streets near our London office to take photo reference of all the roadside assets we needed to recreate. The hummingbird required a few weeks of modeling time to get right.

Jorge Montiel (lead animator): The whole process was complex, because even though we had to show the Audi features, we also had to keep in mind the design work, the animation and the storytelling. Originally we only had 2D concept drawings. We did as much animation early on as we could, but as soon as we started modeling the assets, we had to adjust things as we redefined the shapes.

Click for a larger version.

fxg: How did you then approach the animation of the hummingbird?

Montiel: We wanted to keep the graceful movements of a hummingbird which can be short and snappy, but at the same time we had to reflect some of the qualities of the car and the design of the brand into the behavior of our character. We had to test different behaviors – we used graceful choreography and curves to match the gracefulness of the car. We went through a realistic hummingbird animation to a more stylized and graceful animation. The rig wasn’t that complex because we wanted to keep the sense of the mechanic hummingbird. It was a mix between bird and machine.

Alex Hammond (3D artist): I remember there was a point where we added an extra split into the bird just to get a little more movement into the back end of the tail. It was things like that, especially when you saw it on the move, we’d say, ‘It would be nice to have an extra edge there.’

fxg: Can you describe the texturing, lighting and rendering approach for the hummingbird and the metallic bees?

Bussell: The texturing was a crucial component to the final look of the commercial. Graeme Turnbull pretty much did all the texturing throughout the project. He used Mari to texture which allowed him to paint directly onto the 3D surface and mix various different textures together using its layer system. The shader for the hummingbird and bee was setup by Amaan Akram who acted as rendering TD during the pre-production stage of the project. It was really important to get the anisotropic highlights working well to give that really realistic metallic feel to the hummingbird. We drove the rotation of the anisotropic highlight in UV space. For all texture imperfections of the bee we used various layers exported from Mari to control the various degrees of reflection and roughness to the surface.

Initial render.
Final composite with blurring and flares added.

Hammond: Graeme even went out to take pictures himself and used Mari to develop these levels of texturing. The good thing about Mari is that you can build shaders within the software to visualize how things are going to look before you actually start to render them for real. We used Arnold for rendering. When you’re trying to render realistic environments, you want to maintain that level of exposure you’re getting from the environment – you want to keep that range. So in this sense, Arnold is very good at optimizing high points and highlights and trying to minimize artifacts when you render. In the past we’d sometimes have to almost clamp the lighting just so we don’t get those artifacts.

Bussell: Arnold also handles 3D depth of field and motion blur particularly well and due to the fact we needed to use this on the hummingbird it seemed like the obvious choice to go with. Some of our render times were hitting the hour mark but considering we were rending HD with global illumination, diffused reflections, 3D motion blur and depth of field turned on we thought that was very reasonable.

fxg: How did you handle the motion blur for the flapping wings of the hummingbird and bees?

Montiel: From the animation point of view we had to test a few different cycles, different speeds. The guys in rendering tried different values as well. One issue was that the size of the bird in the shot changes the look of the blur, so we had to keep that in consideration. We had several cycles, with maybe a cycle of three or four frames and a lot of in-betweens in the middle, so that the renderer could read all those in-between frames and make nice shapes.

Hammond: We actually ended up caching out the bird by basically multiplying the animation out five times. So when we cached out the animation it looked a lot slower, but then when we brought it back into our render scene, we put it back to the normal speed and in that way when we actually transformed the motion blur samples, we could actually get a much nicer interpretation of the wings.

fxg: There are a bunch of other assets in the spot, too, seen on the side of the road. Can you talk about how these were created?

Hammond: We started off with concepting the ideas first. One of the tricky things is that you look to the road for reference, but in reality things alongside the road are not that aesthetically pleasing. So from a design point of view we almost simplified things and kept away from the grotesque part of road signs and nuts and bolts. We mainly used XSI – there was a lot of back into and forth of exporting it into TopoGun and re-topologizing it and then bringing it back into XSI.

We had a setup in ICE – we modeled one traffic light and instanced that to gain a particular shape. For the trees in particular we would model a volume first of all that we would fit the traffic lights around. From that respect we could instance the single traffic light and create the big tree. It was the same for the beacons as well – we modeled the landscape and then populated it with a single beacon.

Initial render.
Final comp.

fxg: Was the car real or was it a digital creation?

Hugo Guerra (2D lead artist): The car section was a bit different than the hummingbird part of the spot. We had a live plate but we made sure the light was as flat as possible. So we literally went to the studio to film a diffuse car. We tried to keep the car with no reflections and have as less directional light as possible. We tracked the car and modeled it.

Hammond: We did actually get the CAD data for it, too. The camera move was motion controlled so we then had to replicate the camera movement in 3D.

Guerra: The lighting and rendering team provided us with different layers – both specular lights, rim lights, and extra lights to place the car in that environment.

fxg: Then for compositing, what was the approach for the overall spot?

Guerra: We started using some skeleton scripts and some gizmos in Nuke to reconstruct the EXR passes, to have some set-ups that could be re-used throughout the project. We also used the position pass and normal pass to re-light certain areas of the comp. We also used the 3D system in Nuke by importing the cameras from the 3D and the point clouds in 3D to control all the flares and the volumes that we added in some of the shots. We wanted to bring in all the photoreal aspects of the shots. We looked at lots of references of photos in bright daylight – we’d take pics of objects and even traffic lights just so we could nail all these little glints of sun, the chromatic aberrations – all the subtleties you get from lens distortions and other effects.

The renders were already coming out great, but we started pushing it more and more by referencing the photography. But we always had to still contain it to the Audi world. All the environments were motion blurred and de-focused in comp. We used the typical passes that Arnold provides – a reflection pass, a specular, diffuse and indirect diffuse, but we also had a lot of extra passes – rim passes, normal – to try to do on a shot by shot basis some fake rim lights – not so much to make them photoreal, but just more believable and almost theatrical.


Agency: BBH
Producer: Ruben Mercadal
Creative Director: Nick Kidney, Kevin Stark
Creatives: Paul Yull, Adi Birkinshaw

Production Company: Knucklehead
Director: Daniel Barber
Executive Producer: Matthew Brown

Editing Company: The Whitehouse
Editor: Adam Marshall

VFX Producer: Rahel Makonnen
Shoot Supervisor: Hitesh Patel
2D Lead Artists: Hugo Guerra
3D Lead Artists: Tom Bussell, Jorge Montiel (Lead Animator)
2D Artists: Jerome Lionard, Ben Smith, Emma White, Ben Turner, Neil Davies, Cameron Smither, Juan Brockhaus
3D Artists: Tom Bussell, Alex Hammond, Amaan Akram, Adrian Russell, Adam Droy, Jose Maria Andres Martin, Gemma Aliaga, Tommy Anderson, Stuart Turnbull, Carlos Fraiha, Ciaran Moloney, Sergio Xisto, Graeme Turnbull, Melanie Tonkin, Jorge Bellott, Francois Roisin, Nicolas Guiraud, David Hempstead, Mattias Bjurstroem, Adam Darrah
Assist: Scott Dawkins
Colourist: Aubrey Woodiwiss, Mick Vincent
Art Department: Jimmy Kiddell, Can Y. Sanalan, Carlos Nieto, Mel Climent, Jiyoung Lee

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