computer science

Shader lamps

Shader lamps is a computer science 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 Shader lamps rather than just read about it. In short: Shader lamps is a computer graphic technique used to change the appearance of physical objects. The still or moving objects are illuminated, using one or more video projectors, by static or animated texture or video stream.

Key takeaways

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

Reference excerpt

Shader lamps is a computer graphic technique used to change the appearance of physical objects. The still or moving objects are illuminated, using one or more video projectors, by static or animated texture or video stream. The method was invented at University of North Carolina at Chapel Hill by Ramesh Raskar, Greg Welch, Kok-lim Low and Deepak Bandyopadhyay in 1999 [1] as a follow on to Spatial Augmented Reality [2] also invented at University of North Carolina at Chapel Hill in 1998 by Ramesh Raskar, Greg Welch and Henry Fuchs. A 3D graphic rendering software is typically used to compute the deformation caused by the non perpendicular, non-planar or even complex projection surface. Complex objects (or aggregation of multiple simple objects) create self shadows that must be compensated by using several projectors. The objects are typically replaced by neutral color ones, the projection giving all its visual properties, thus the name shader lamps. The technique can be used to create a sense of invisibility, by rendering transparency. The object is illuminated not by a replacement of its own visual properties, but by the corresponding visual surface placed behind the object as seen from an arbitrary viewing point.

See also Projection augmented model Projection mapping

External links Shader Lamps, Projector Based Augmented Reality, Raskar, MIT Media Lab Mitsubishi Electric Research Laboratories, Shader Lamps, Ramesh Raskar, Greg Welch, Kok-lim Low, Deepak Bandyopadhyay, June 2001 (PDF) IEEE Computer Society January/February 2007 (Vol. 27, No. 1) pp. 90-96, The Digital Chameleon Principle: Computing Invisibility by Rendering Transparency Frank Nielsen, Sony Computer Science Laboratories

Worked examples

Example 1 — a first encounter with Shader lamps

Start with the simplest possible case. Write down what Shader lamps claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, 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 Shader lamps 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 Shader lamps 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 Shader lamps

In research: Shader lamps appears in computer science 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 Shader lamps 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: Shader lamps is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computer graphics, Computer graphics stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Shader lamps 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 Shader lamps in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Shader lamps 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 Shader lamps out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Shader lamps in simple terms?

Why does Shader lamps matter?

Because it connects several computer science 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 Shader lamps?

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 Shader lamps.