Here, Travers discusses Epic with CGW Contributing Editor Barbara Robertson. (Also read a Q&A with Chris Wedge in the May/June 2013 issue of CGW , and two others with CTO Carl Ludwig and Materials Supervisor Brian Hill online and accessible via the May/June 2013 issue box on cgw.com.)
Mandrake (Christoph Waltz) flies into battle to claim the forest he believes should have always been his. Photo: Blue Sky Studios.
In making this film, what was most challenging?
We have some very complicated action sequences with a witches' brew of everything going on. Dynamic cameras, large character counts, complex flight choreography, interaction with effects, in a dense forest environment all created a huge challenge to get it coordinated and looking right.
The look of the world was what we spent the most time on; the look of a world from the perspective of people who are very small. We studied macro-photography of flowers, fauna, and skin textures. When you look at the micro-details of the things around us in nature, it's almost like science fiction. We had to reflect this in our environments. We also looked at stop-motion photography of plants growing, snails crawling, and so forth to create an overarching visual theme. Then, we broke it down piece by piece and implemented all these references in our production.
The film also takes place in a normal-sized world. Was it difficult to move from one to the other?
When we transition from the human-scaled to the leafman-scaled world, we use a lens package that's slightly wider with a narrower depth of field to create a definite separation from the leafman perspective to the human perspective.
We also slowed everything down. The humans haven't seen this world before. To a human's eye, the leafmen move so fast they can always stay hidden. So, from the perspective of characters in the small scale world, everything is slower and we use that to keep the audience oriented. Characters ride hummingbirds, but instead of 700 wing beats per minute, we knocked that speed way down. Our entire library of effects - splashes, smoke, water caustics, moving background vegetation, and so forth - were all slowed down maintain a consistent visual theme.
Keeping all that straight seems mind-boggling.
A lot of smart people spent a great deal of time and effort defining the rules and look of the world. We had a plan per sequence of how everything would work at the leafman scale, the human world scale, and the transitions in between. After that, it was a matter of maintaining consistency.
Buffo (Pitbull) is a wheeler and dealer tough-guy toad who plays all the angles: he profits no matter which side wins or loses. Photo: Blue Sky Studios.
How did the small scale affect production?
The artists who created textures at a normal scale had to add details when a small person is looking at the same thing. We had to change surface shaders and play with translucence and transmittance to get the right feel of light passing into them. Additional modeling details were added. We did a great deal of research to make sure we captured the essence of the leafman world. A typical example: Any time there is an object intersecting with a water surface, we had to create a meniscus to sell the effect. When you are two inches tall, the meniscus looks like a three-inch berm. It's huge.
Did the crew build separate assets for each world?
We needed to build two libraries of assets for each of the two world scales. We'd build everything to work at human size, then rebuild or add assets for the leafman scale. To a two-inch-tall leafman, a 60-foot elm tree is as big as a skyscraper, so we had to add details to work for close-ups. Our materials artists relied heavily on nested procedural shader systems to reduce the number of large-resolution texture maps loaded in the renderer.
How many characters did the crew build and animate?
In terms of unique character rigs, around 40. For background characters, we adjusted materials and textures to make variations. There are characters whose design is meant to invoke mystery, the Jinn, that blend into their environment. There are the bad guys, the Boggans, that are more amphibious and reptilian in nature. We also have a handful of unique forest creatures and many bird types. And, of course, our hero characters and the leafmen.
MK (Amanda Seyfried) encounters a slug named Mub (Aziz Ansari), a self-described "ladies man." Photo: Blue Sky Studios.
One of the big rigging challenges were Mub and Grub, a slug and a snail. They don't have joint structures that lend themselves easily to rigging. They don't have arms or legs. Their bodies can ride along any topology. Their eye stalks can retreat into their heads. On top of those challenges, they are comedic and expressive characters, so we had to put in wide range of face controls on top of an already complex rig. We spent a year developing the rig for the Mub before animators got going on the first shot.
The leafmen armor represented a challenge for the character simulation team due to the many layers and pieces of their ornate designs. They were also challenged by the fact that leafmen-scaled characters can suddenly jump great distances. They had to constantly tune the settings and values for the cloth simulations and babysit the aggressive movements to keep the clothes from flying off.
When the forest and his beloved Queen come under siege, Ronin (Colin Farrell) takes to the skies to protect them. Photo: Blue Sky Studios.
Did you reference superheroes for the leafmen?
We studied what physics is like in a world this small. We looked at creatures like crickets that can jump far and fall great distances and not get hurt. We looked at ants that can carry six to 10 times their body weight.
There are fantasy elements in the film, but the underpinnings of scale are based on real-world examples. This is a big film with real emotional stakes and great characters. You ride through the film with them. It's an exciting, fun story.