Utah teapot

The Utah teapot or Newell teapot is a 3D model which has become a standard reference object (and something of an in-joke) in the computer graphics community. It is a simple, round, solid, partially concave mathematical model of an ordinary teapot.

The teapot model was created in 1975 by early computer graphics researcher Martin Newell, a member of the pioneering graphics program at the University of Utah. Newell needed a moderately simple mathematical model of a familiar object for his work, and his wife's teapot, a Melitta, provided a convenient solution. The shape contains a number of elements that made it ideal for the graphics experiments of the time &mdash; it is round, contains saddle points, has a genus greater than zero because of the hole in the handle, can project a shadow on itself, and looks reasonable when displayed without a complex surface texture.

Newell made the mathematical data that describe the teapot's geometry (largely a set of three-dimensional coordinates) publicly available, and soon other researchers began to use the same data for their computer graphics experiments. These researchers needed something with roughly the same characteristics that Newell had, and using the teapot data meant they didn't have to laboriously enter geometric data for some other object. Although technical progress has meant that the act of rendering the teapot is no longer the challenge it was in 1975, the teapot continued to be used as a reference object for increasingly advanced graphics techniques.

Over the following decades, editions of computer graphics journals (such as the ACM SIGGRAPH's quarterly) regularly featured versions of the teapot: faceted or smooth-shaded, wireframe, bumpy, translucent, refractive, even leopard-skin and furry teapots were created.

Versions of the teapot model, or sample scenes containing it, are distributed with or freely available for nearly every current rendering and modeling program, including AutoCAD, POV-Ray, OpenGL, Direct3D, and 3D Studio Max. Along with the expected cubes and spheres, the GLUT library even provides the function  as a graphics primitive. BeOS included a small demo of a rotating 3D teapot, intended to show off the platform's multimedia facilities.

Teapot scenes are commonly used for renderer self-tests and benchmarks. In particular, the Teapot in a stadium benchmark and problem refer to the tough case of rendering of a scene with drastically changing density and scale of geometrical data representation in various parts of the scene.

With the advent first of computer generated short films, and then of full length feature films, it has become something of an in joke to hide a Utah teapot somewhere in one of the film's scenes. Utah teapots can be found in Toy Story, Monsters Inc., and Disney's Beauty and the Beast. The teapot also occasionally appears in the Pipes screensaver shipped with Microsoft Windows. It is also featured in one of the levels of the video game Super Monkey Ball 2, in technological demo section of Serious Sam, and can be found in Microsoft Train Simulator. By using a cheat code it is possible to have a Utah teapot as an avatar in the Star Wars: Knights of the Old Republic PC game.

The original teapot was never seen from below and has no surface to represent the base of the teapot. Later versions fixed this.

The original, physical teapot now resides in the Computer History Museum in Mountain View, California. It is noticeably taller than the Utah teapot, because Newell's frame buffer used non-square pixels. Rather than distorting the image, Newell's colleague Jim Blinn reportedly scaled the geometry to cancel out the stretching, and when the model was shared with users of other systems, the scaling stuck.