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Director and producer Di He at AIVFX in Canada explains the value of computer science and programming in developing customized render and production pipelines for animation. He and his team recently produced ‘The Birthday Gift’, a prizewinning animated short film.


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Di He is a director and producer of animated films, originally from China and now based in Toronto at Authentic Illusion VFX, has a background in both classical sculpture and computer science. When Di was studying for sculpture at art college in China in the mid-nineties, computer graphics resources were still not as accessible to Chinese art students as they were elsewhere.

Programming Perspective
By the time he graduated in 2000, however, he had a chance to try using Maya and 3d Studio Max on some Pentium 3 computers, and was inspired by what computer software could offer artists. Di went to Canada and earned a degree in computer science. With no real understanding of computer animation yet, Di’s science background was to become criticalwhen working as an animator later. He realized how important it is for artists to understand computer science if they really want to take advantage of computer techniques.

“I could approach software from a programmer’s perspective instead of only as an artist. I use this knowledge in my work every day and it makes a huge difference. Some things can only be achieved through programming – shaders, VFX simulations, rendering and lighting – and cannot be mastered purely through artistic skill. Artists also need to understand the physical principles controlling how the computer displays lighting and colour, for example.” He finds this understanding invaluable for computer animation.

Di designed the whole rendering pipeline for the projects at AIVFX, which runs with a very small team, as well as the production pipeline to customize and streamline the workflow. It took Di about a week to set up the render pipeline, based mostly on 3Delight with the addition of in-house shaders and 3-point light setups, with additional lights when needed.

“Production time on ‘The Birthday Gift’, with a team of only five, was just three months,” Di said. “We try to focus on efficiency, so no one has to set up scenes from scratch. Each person concentrates on being very skilled at what they do, and communicating with all the other members in the team.”

Renaissance Painting
Set in China in the late ‘70s during the economic transition after the Cultural Revolution, ‘The Birthday Gift’ is a story about a little boy who sacrifices his favourite toy and works to pay for glasses for his grandmother. As the team developed the three main characters, a little boy, his grandmother and a shop keeper, they actively avoided a Japanese or American cartoon style. “We were looking for a realistic, classical style almost like a Renaissance oil painting. We were telling a moral story without much scope in the script for humour and funny gestures,” said Di.

“The characters are based mostly on some photographs we found online. I’d say the most challenging of these was the grandmother, an old lady. She has to portray someone who is very poor but also very kind. The way she talks, her expressions and overall behaviour were quite difficult for us to capture.”

Blending Animations
This was the first production in which they used Maya’s Trax editor in their pipeline for blending animations. The animator could work on one kind of action such as a run or a jump, really perfect it and then use Trax to work out the in-between frames. “We only had the one animator, and using this meant he could concentrate more on looks, expressions and specific movements.”
The team’s CG Superviser, Production Manager Brock Lafond talked about establishing a sense of scale, depth and emotion in the environments, an important task on the production. “We wanted to be sure that viewers would believe the locations they saw could be real places, and are meant for the characters to exist in. For many scenes we specifically placed visual cues and references to help define the scale,” he said.

“Scale, however, was difficult to figure out for this production, and we decided to make an environment that ‘fits’. Even though not every object is at a proper scale, they have all found their places and feel right. We based a lot of the environment design on our own memories and feelings. Using photo reference was almost secondary.”

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Composition and Colour
For composition, they spent a lot of time visualizing themselves in the environments, and literally rearranged the office space to match the environments. Once they understood the actions and emotions that needed to be conveyed and the space that it had to take place in, they began playing with camera angles. The angles that felt right were chosen.

Every location has a carefully chosen colour palette to help establish the mood, and time was spent ‘painting with light’. The particle systems in 3DS Max and Particle Flow were used to generate subtle snow, smoke and fog effects to bring more realism to the film, but the setting is mean to transcend the natural world. “Each frame is in essence a Renaissance painting – the environments are lit with warm inviting lighting and care was taken to perfect the composition of each shot,” Brock said.

Bouncing Logs
“We used traditional modelling methods, but had to come up with a few of our own. Some more creative techniques involved the Reactor dynamics simulator in 3ds Max to fill containers with walnuts, for example. It also helped generate very natural solid body placement around the scene. For the wood pile in the grandmother’s house, we first made a few different types of detailed logs. Low-res proxy objects were attached to the logs to use in the Reactor simulation. When the proxies were brought into Reactor along with a simple environment, we could literally throw logs into place. The harder we threw the log, the more it would bounce and potentially create a mess of the other logs. It was actually quite fun.

“In addition to Reactor, we also used 3DS Max cloth to help model some organic models and, of course, cloth objects. We had an exact idea of how most objects should look, and often had detailed digital paintings to guide the modellers. The clock that sits on the store shelf is unusual. Chinese characters in the middle circle represent the numbers and the inner Chinese characters represent the part of the day.”

Broken Seams
Mudbox and ZBrush were their primary texture programs because of their projection tools for painting directly on the mesh and extend UV edge pixels very easily to avoid broken seam problems. “When painting textures on an object that has been UV mapped, you have to be careful when approaching an edge of a UV island, a group of polygons in the UV map that are detached from the rest of the polygons, producing a seam,” Brock explained. “An example of this is the symmetry line on a bottle or jar. When painting on the edge, we had to make sure that pixels on both sides of this seam would match up, to avoid a noticeable line. Subdividing the object can also subdivide and smooth out the UV map, and cause it to completely miss the painted texture.”

One of the challenges we had to overcome was the fluidity of the cloth motion on all three characters. We were trying to create very thick cotton, similar to denim, but more flexible. We had to control the flexibility and overall movement to let us dictate the overall look, while maintaining a believability of dynamic motion. With a lot of testing and adjusting we were able to create a cloth in Maya nCloth that behaved realistically.

Upstaged
As animators from a western society, one of their challenges was to try to achieve the character mannerisms and subtleties of the characters and their culture through body language and expressions. “Di filled the gap between the western and eastern cultures by explaining each character’s own situation at that time in their life and how they all related to each other. It was a challenge at first to use Maya Trax to make believable blending animations but once we got it working correctly it saved us a lot of time and we were able to work on more animations,” said Brock.

He agreed that the grandmother was a challenge. “She had to be appealing and represent a grandmother to many types of cultures, as this production is intended for international showing. We asked ourselves, ‘How wrinkled should she be? How healthy is she? Do we want the audience to worry about her?’ She went through a few hair styles before we settled on one. And, with all of this attention going into her, we had to make sure that she didn’t steal the spotlight from our main character, her grandson.”

Di mentioned that they were using eyeon's asset management software, Generation, as well. “It allowed us to see the shots and how we wished to adjust them. We didn’t use it everyday from the beginning but found it very useful toward the end when we ran into a number of small problems. We could create several versions of a scene, then use Generation Studio to track differences between them and decide quickly which one to choose for the edit. We use it to manage designs, lighting tests, animation takes and so on.

Best Short Film
“Everyone on the team worked to make this production very original. I wanted to make the boy in the story a believable character, not a symbolic version of what a boy is like or should be like, but a real person faced with a difficult decision.” Their work has paid off. The production won the Best Animated Short Film prize at the First China International New Media Movie Television Animation Festival, and Di was awarded Best Animated Short Film Director. Since then, it has been officially selected at several other festivals including the Chicago International Children's Film Festival and the SIGGRAPH Asia 2010 Animation Theatre.

Recently, the team has been working with Hall Train Studios, an archeological design and animation company in Canada, on dinosaur animations for the New York Natural History Museum using Lidar scans of models based on scientific research. AIVFX have developed software for rendering millions of long and short hairs and fur very rapidly. “You can see where we used this for the old lady in ‘The Birthday Gift’. She has very long hair, which is always a challenge for rendering,” said Di.

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chinese painting
Brock had been used to Autodesk and Adobe software for compositing but they used Fusion 6 on this project, which meant changing from layers to nodes. He liked the Fusion 3D particle system. “One challenge in our development was to capture the nature spirit of Chinese painting. Fusion handles 3D animated clouds, fog, water and snow environment and gave almost real-time feedback in our final compositing view, like working in front of a moving canvas. We also designed a set of Fusion scripts with naming sequences and shots based on a database. When the artists opened a Fusion file, the image loader, frame number, time code and output are ready, which saved time. We had 120 shots, all done in Fusion.”
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Words: Adriene Hurst with Di He and Brock Lafond
Images: Courtesy of AIVFX and Brock Lafond
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