Utah Teapot - History

History

Newell needed a moderately simple mathematical model of a familiar object for his work. His wife Sandra Newell suggested modelling their tea service since they were sitting down to tea at the time. He got some graph paper and a pencil, and sketched the entire teapot by eye. Then he went back to the lab and edited bézier control points on a Tektronix storage tube, again by hand.

The teapot shape contains a number of elements that made it ideal for the graphics experiments of the time: 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 described the teapot's geometry (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 did not 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.

The original teapot model was never intended to be seen from below and had no surface to represent the base of the teapot; later versions of the data set have fixed this.

The real teapot is noticeably taller (by a ratio of 4:3) compared to the computer model 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. This account was however later contradicted by Jim Blinn himself, who stated that he scaled the model on the vertical axis during a demo in the lab to demonstrate that they could manipulate it. They then liked the way this new version looked and saved the file.

The original, physical teapot was purchased from ZCMI (a department store in Salt Lake City, Utah) in 1974. It was donated to the Boston Computer Museum in 1984 where it was on display until 1990. It now resides in the ephemera collection at the Computer History Museum in Mountain View, California where it is catalogued as "Teapot used for Computer Graphics rendering" and bears the catalogue number X00398.1984.

Versions of the teapot model, or sample scenes containing it, are distributed with or freely available for nearly every current rendering and modelling program and even many graphic API, including AutoCAD, Houdini, Lightwave 3D, modo, POV-Ray, 3D Studio Max, and the OpenGL and Direct3D helper libraries. Some RenderMan-compliant renderers support the teapot as a built-in geometry by calling RiGeometry("teapot", RI_NULL). Along with the expected cubes and spheres, the GLUT library even provides the function glutSolidTeapot as a graphics primitive, as does its Direct3D counterpart D3DX (D3DXCreateTeapot). Mac OS X Tiger and Leopard also include the teapot as part of Quartz Composer; Leopard's teapot supports bump mapping. 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.