# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/Dcgki8_gUsx
- **Gondola URL:** https://gondola.cc/posts/69727803-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/0f246c12a1.jpg
- **Posted:** 2026-08-26T15:58:57.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

In 1965 the University of Utah hired back a physics PhD, David Evans, to start a computer science department. Almost every pixel you have ever seen in a 3D film traces to that decision.

Evans recruited Ivan Sutherland in 1968, on the condition they start a hardware company together. ARPA funding followed and Utah became the centre of gravity for computer graphics. One student in that lab was Ed Catmull.

Catmull’s 1974 thesis, “A Subdivision Algorithm for Computer Display of Curved Surfaces,” is arguably the most consequential document in animation history. It solved two problems that had nothing obvious to do with cartoons.

The first was visibility. Project 3D geometry onto a 2D screen and surfaces overlap, so the machine must decide what hides what. Existing methods sorted the whole scene geometrically before drawing: expensive, and broken by interpenetrating shapes. Catmull’s answer was the Z-buffer:

• Allocate a second buffer holding a depth value per pixel
• Initialise every depth to infinity
• As each fragment is drawn, compare its z to the stored value
• Overwrite the colour only if the new fragment is nearer

No sorting. No global ordering. A per-pixel comparison trading memory for computation when memory was the expensive resource. Every GPU shipped today still does this in silicon.

The second was surface detail. Modelling every wood grain and paint scratch as geometry is hopeless. Catmull instead mapped a flat image into the parametric u,v coordinates of a curved patch. Texture mapping. Detail became a lookup, not a polygon.

Curved surfaces he handled by recursive subdivision: split a bicubic patch until each piece is smaller than a pixel, then shade it. That idea became REYES, then RenderMan.

He applied for academic jobs after graduating. Nobody hired him. He built Pixar instead.

Imaginary worlds got built by people trying to draw one curved surface correctly.

#stemantics #computergraphics #computerscience #engineering #pixar

## Stats

- **Views:** 4,013
- **Likes:** 53
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## Tags

pixar, engineering, computergraphics, computerscience, stemantics

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