Utah teapot
Utah teapot
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Utah teapot

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Utah teapot

The Utah teapot, or the Newell teapot, is one of the standard reference test models in 3D modeling and an in-joke within the computer graphics community. It is a mathematical model of an ordinary Melitta-brand teapot designed by Lieselotte Kantner [de] that appears solid with a nearly rotationally symmetrical body. Using a teapot model is considered the 3D equivalent of a "Hello, World!" program, a way to create an easy 3D scene with a somewhat complex model acting as the basic geometry for a scene with a light setup. Some programming libraries, such as the OpenGL Utility Toolkit, even have functions dedicated to drawing teapots.

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. It was one of the first to be modeled using Bézier curves rather than precisely measured.

For his work, Newell needed a simple mathematical model of a familiar object. His wife, Sandra Newell, suggested modelling their tea set since they were sitting down for tea at the time. He sketched the teapot free-hand using graph paper and a pencil. Following that, he went back to the computer laboratory and edited bézier control points on a Tektronix storage tube, again by hand.[citation needed]

The teapot shape contained a number of elements that made it ideal for the graphics experiments of the time: it was round, contained saddle points, had a genus greater than zero because of the hole in the spout, could project a shadow on itself, and could be displayed accurately without a 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.

Having no surface to represent its base, the original teapot model was not intended to be seen from below. Later versions of the data set fixed this.

The real teapot is 33% taller (ratio 4:3) than the computer model. Jim Blinn stated that he scaled the model on the vertical axis during a demo in the lab to demonstrate that they could manipulate it. They preferred the appearance of this new version and decided to save the file out of that preference.

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