Avatar 3 Fire FX Revealed: Engine Driven by Real Chemistry & AI

carlosdponx · x · 2026-07-25

At a SIGGRAPH production session for Avatar: Fire and Ash, the VFX team unveiled a new fire solver designed for ultimate realism.

The engine calculates and renders fire based on actual chemical properties, such as oxygen and fuel. However, this physics-driven approach proved difficult for artists: changing fuel levels without compensating for oxygen caused failed ignitions, and only about 4 people in the company had the chemistry knowledge to tune it correctly.

To solve this, the team built Kora, a machine learning system. Artists simply specify their desired visual results, and Kora automatically generates the correct chemical properties required to achieve them, streamlining the workflow.

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