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.
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.
