We present Kora*, a fire system for visual effects production. It consists of (i) a weakly compressible, sparse, spatially adaptive, MPI-distributed physics-based combustion solver, featuring a novel energy cascade turbulence model and support for adiabatic cooling; (ii) a Houdini-centric abstraction layer that exposes the advanced combustion routines through intuitive, artist-friendly interfaces. Key components include customizable premixed fuel sourcing, liquid-gas coupling and vaporization, control and art-direction utilities, as well as physics-based shading and render-graph integration. We describe the architecture of Kora, its solver foundations, and how we put it into practice in
Avatar: Fire and Ash. We were honored to be awarded the
Visual Effects Society (VES)
2026 Emerging Technology Award for this work.
Alexey Stomakhin,
John Edholm,
Murali Ramachari,
Aleksandr Isakov,
Zahra Forootaninia,
Marcus Schoo,
Nicholas Illingworth,
Joe Letteri
DigiPro 2026
*Kora is te reo Māori for spark.
