# Big Hero 6's city had half a million lights, and one block was too big for 64 GB.

- Series: [How It's Clipped](https://miu.fm/howitsclipped.md)
- Published: 2026-10-22
- Page: https://miu.fm/howitsclipped/big-hero-6-s-city-had-half-a-million-lights-and-one-block

## Story

Big Hero 6's city had half a million lights, and one block was too big for 64 GB. Guess how Disney rendered it.

In 2014 Disney Animation wrote a new renderer for one film. Path tracing a city means light that bounces "randomly, encountering objects in an unpredictable order", and every bounce reaches for a different texture: "incoherent access to production-scale texture data incurs frequent cache-misses, leading to memory, disk and network delays that dominate run-time." Rendering "even a fraction of one city block" in an existing ray tracer "exceeded the 64GB physical memory limit". So Brent Burley's team stopped following rays one at a time. Hyperion collects rays in batches "of up to 33 million", bins and sorts them by direction so a bundle hits the same things, then sorts the hits, so "each mesh face is touched at most once" and every texture is read once, in order. In their 2013 test the same renderer without sorting was "around 70× slower". "We couldn't make 'Big Hero 6' with the tools we used to make 'Frozen'," Burley said.

Our own city, rays and texture strip (a 2D toy; the read counts on screen are ours); no frames from the film.

Ever waited on a render? Tell us your longest.

Sources: Eisenacher, Nichols, Selle and Burley, "Sorted Deferred Shading for Production Path Tracing", EGSR 2013; Burley et al., "The Design and Evolution of Disney's Hyperion Renderer", ACM TOG 2018; Walt Disney Animation Studios, Hyperion; Big Hero 6 production notes (Disney, 2014).
Sounds: our own, made in code (earshot, CC0).

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