A Biography of the Pixel by Alvy Ray Smith

A Biography of the Pixel by Alvy Ray Smith

Author:Alvy Ray Smith [Smith, Alvy Ray]
Language: eng
Format: epub
Tags: Xerox PARC; Lucasfilm; Pixar; DreamWorks; Blue Sky; Kotelnikov; Turing; von Neumann; Edison; Dickson; Disney; Iwerks; Lumiéres; Muybridge; Fourier waves; Sampling Theorem; Great Digital Convergence; Central Dogma; idea-chaos-tyrant triad; shading language; Moore’s Law; digital movies; character animation; computer graphics; first computer; Tron; Toy Story; Antz; Cars;
Publisher: MIT Press
Published: 2021-07-14T00:00:00+00:00


Tim Johnson in Perspective

Tim Johnson had the misfortune of looking a lot like Ivan Sutherland in the early 1960s. He had a bigger, readier smile than Sutherland but the same hair, glasses, and narrow face. Many online photos today, captioned as Sutherland at the controls of Sketchpad, are actually Johnson at the controls of Sketchpad III. When I contacted Johnson in late March 2017, he good-naturedly accepted the situation. He’s now resigned to it, he said. What else could he do? I promised him I would do my bit to turn it around.

Johnson’s Sketchpad III was in the main line of computer-aided design development. With it he introduced, as we’ve mentioned, the four-pane window layout popular with computer-aided design modelers: three showing top, front, and side views of an object without perspective, and the fourth, the viewport, showing the object from any angle and in perspective using the Roberts perspective solution.

Consider that viewport for a moment. Assume that it fills the entire display. That’s the view you see in every frame of every Pixar-like movie. Those other three panes, with the top, front, and side views, are used during the design phase only, for the convenience of modelers.

In figure 6.34, upper left, Johnson (not Sutherland!) is at the controls of Sketchpad III. The closeups of each display show all four panes, with the viewport in the upper right of each. Tim started with three faces of a simple cube (in the upper right figure). He then added, using a light pen, a triangle at the top of the front face F (lower left), which shows in the other panes as he adds it. He then added (lower right) a skewed rectangle to the side face S and perhaps is adding another to front face F.75

The viewport was Johnson’s innovation: “Ivan [Sutherland] got the homogeneous thing going by pointing me in Larry Roberts’s direction. I quickly appreciated how clean (and brilliant) his [Roberts’s] approach was. . . . The perspective view port was my notion.” And that (perspective) viewport notion is key to computer graphics.76

I asked Johnson if he had implemented Coons patches in Sketchpad III, given that Coons was his master’s thesis adviser. “I did Steve’s patches as a quick and dirty stand-alone TX-2 program, it was not part of Sketchpad III.”77



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