Lead software engineer Curtis Andrus and software developers Anika Andrus and Suwen Wang at MPC Film talked about the work and main considerations that went into to developing fur for everyone’s favourite Pokémon in Detective Pikachu.
The work on the film involved hundreds of shots of Pikachu. To maintain a soft and fluffy look, Pikachu’s fur was made reasonably long. The length of Pikachu’s hair created several challenges when aiming to successfully maintain its softness. In order to overcome these challenges, MPC Film developed new tools and workflows. Typically, creating CG grooms for fluffy characters with long fur has been a challenge for several reasons. A few of these are:
- Fur Separation/clumping in response to deformation in the underlying skin (we referred to this as a “slashing” pattern – see image below)
- Interactions within the groom itself and with other geometry became more obvious at longer length. Even shots with Pikachu sitting with arms at his sides required special care, due to the interaction between the arm and the belly fur.
Artist-defined slashing pattern
Getting the right amount of details for these effects is either too complex or too computationally intensive with our typical workflows of sparse guide curve simulation.
Moreover, since simulation is too costly, the team decided to build these effects directly into the grooms. MPC Film uses our in-house tool Furtility, which procedurally generates hair curves at render-time.
To make fur respond to interaction with other objects in the scene, we re-used an existing geometry operator in Furtility called the “Surface Flow” Operator, which pushes hair along the surface. The resulting effect is that fur is pushed back towards the surface whenever objects gets too close.
Furthermore, regular clumping in Furtility is done by attracting groom curves to a set of sparse clump curves, where each clump curve controls the overall shape of that clump. The MPC team implemented what they called a “textured clump” operator that bunches curves together in an artist-definable slashing pattern. The team drove the influence of this operator dynamically through attributes indicating the stretch/compression of Pikachu’s skin. So, whenever Pikachu does actions like stretching his arms, the slashing effect becomes more apparent.
These tools and workflows proved to be extremely powerful and without it, artists would have to manually sculpt guide curves in certain shots, or simply push the look towards shorter hair, taking away from the desirable soft and fluffy look of the Pokémon.
TechAnim artists are just starting to learn what they can achieve with these tools and are excited to see novel and creative use cases in the future. – thefocus.com
Read the full article on the MPC R&D website here.