astronomy

Tom Duff

Tom Duff is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Tom Duff rather than just read about it. In short: Thomas Douglas Selkirk Duff (born December 8, 1952) is a Canadian computer programmer. Life and career Early life Duff was born in Toronto, Ontario, Canada, and was named for his putative ancestor, the fifth Earl of Selkirk.

Key takeaways

Tom Duff belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Tom Duff to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Tom Duff from memory before moving on to harder problems.

Reference excerpt

Thomas Douglas Selkirk Duff (born December 8, 1952) is a Canadian computer programmer.

Life and career

Early life Duff was born in Toronto, Ontario, Canada, and was named for his putative ancestor, the fifth Earl of Selkirk. He grew up in Toronto and Leaside. In 1974 he graduated from the University of Waterloo with a B.Math and, two years later, was awarded an M.Sc. from the University of Toronto.

Programming career Duff worked at the New York Institute of Technology Computer Graphics Lab and the Mark Williams Company in Chicago before moving to Lucasfilm's Computer Research and Development Division. He and Thomas Porter, another Lucasfilm employee, developed a new approach to compositing images; their 1984 paper, "Compositing Digital Images", is "[t]he seminal work on an algebra for image compositing", according to Keith Packard, and "Porter-Duff compositing" is now a key technique in computer graphics. (See, for example, XRender and Glitz.) Duff later worked for 12 years at Bell Labs Computing Science Research Center, where he worked on computer graphics, wireless networking, and Plan 9; in the course of his work there, he authored the well known "rc" shell for the Version 10 Unix operating system. Duff worked at Pixar Animation Studios from 1996 until his retirement in 2021.

Achievements In 1995, he was awarded (with others) the Academy Scientific and Engineering Award for his work on digital image compositing. With Bill Reeves he designed the first version of Pixar's Marionette 3-D animation system, which won the same award in 1997. While working at Lucasfilm, he created Duff's device, a loop unrolling mechanism in C. On August 22, 2006, the United States Patent and Trademark Office issued U.S. patent 7,095,409 to Pixar for a "Shot shading method and apparatus" invented by Tom Duff and Robert L. Cook. On October 31, 2006, the United States Patent and Trademark Office issued U.S. patent 7,129,940 to Pixar for a "Shot rendering method and apparatus" invented by Tom Duff and Robert L. Cook. In 2015 he became the 21st awardee of the J.W. Graham Medal, named in honor of Wes Graham an early influential Professor of Computer Science at the University of Waterloo, and annually awarded to an influential alumnus of the university's Faculty of Mathematics.

In the media Tom Duff makes a cameo appearance in the Niven/Pournelle science fiction novel Footfall as a co-discoverer of the invading spaceship: "Chap named Tom Duff, a computer type, spotted it." Tom Duff appears briefly in the documentary film "Noisy People" (dir Tim Perkis, 2006) playing the banjo.

See also Mothra, a Web browser Tom Duff wrote for Plan 9 List of people by Erdős number, Duff has an Erdős number of 2 List of Pixar staff List of University of Waterloo people

References

External links Tom Duff (short cv on family web site) iq0 (personal web site) rc - The Plan 9 Shell A Quick Introduction to the Plan 9 Panel Library, a GUI toolkit by Tom Duff Tom Duff "Viral Attacks On UNIX System Security", AT&T 11273-880728-02TMS, August 1987

Illustrations

Worked examples

Example 1 — a first encounter with Tom Duff

Start with the simplest possible case. Write down what Tom Duff claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Tom Duff before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Tom Duff ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Tom Duff

In research: Tom Duff appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Tom Duff in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Tom Duff is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1952 births, Computer graphics professionals, J.W. Graham Medal awardees, so understanding it makes those chapters shorter.
In everyday life: Look for Tom Duff outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Tom Duff in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Tom Duff means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Tom Duff out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Tom Duff in simple terms?

Thomas Douglas Selkirk Duff (born December 8, 1952) is a Canadian computer programmer. Life and career Early life Duff was born in Toronto, Ontario, Canada, and was named for his putative ancestor, the fifth Earl of Selkirk.

Why does Tom Duff matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Tom Duff?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Tom Duff.