physics

Illusion knitting

Illusion knitting is a physics 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 Illusion knitting rather than just read about it. In short: Illusion knitting or shadow knitting is a form of textile art, in which the knitting is viewed as simply narrow stripes from one angle, and as an image when viewed from another angle. Illusion knitting has been recognised as an art form since 2010, largely due to the advances made by Steve Plummer who has created several large and detailed pieces.

Key takeaways

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

Reference excerpt

Illusion knitting or shadow knitting is a form of textile art, in which the knitting is viewed as simply narrow stripes from one angle, and as an image when viewed from another angle. Illusion knitting has been recognised as an art form since 2010, largely due to the advances made by Steve Plummer who has created several large and detailed pieces. Similar effects occur in Tunisian crochet.

Method Illusion knitting uses two colours of yarn and is worked in stripes of two rows in each colour. Illusion knitting is based on the flat smooth stocking stitch and the raised garter stitch. It is this combination of textures which allows the image to be seen only from the proper angle. Traditionally, charts for illusion knitting use four rows of knitting symbols to represent the stitches which the designer wishes to be seen. This makes the charts elongated and difficult to use for anything other than simple blocks of colour. These four rows make up two pairs where, in most cases, one pair is considered the opposite of the other. Where one pair has two rows of knit stitches, the other image pair has both knit and purl stitches. As in mosaic knitting, the knitter alternates between two colors. Colors with good contrast are preferred but are not required. The knitter knits two rows of color A, then two rows of color B, and repeats this throughout the body of the work. Only knit or purl stitches are used.

Each row in the pattern, shown in the thumbnail to the right, represents four rows of knit or purl stitches, and each column represents one stitch. To follow this pattern, a knitter would use black and white: white being the background color (BC), and black being the master color (MC).

Start at row one. This could be thought of as Row 1-1 and is a right-side row (RS). Row 1-1 (RS): With BC, knit. Row 1-2 (still following the pattern at row 1) (WS): Knit the blank boxes, purl the ones filled in. Row 1-3 (RS): Change to MC, knit. Row 1-4 (WS): Purl the blank boxes, knit the ones filled in. Move to Row 2 on the pattern and begin knitting the BC. (This is row 2–1.) Repeat for all rows and bind off. The visual effect of shadow knitting is due to the different height of the knit stitches on the wrong side rows. A knit stitch is flat, while a purl stitch is raised. Therefore, one can change which color (dark or light) stands out by changing from knit to purl. So the basic idea is to create a pattern in knit stitches in the colors one wants and purl stitches in the background color. When looking straight at the knitted piece, the stitches look approximately the same, but from an angle, only the raised purl stitches are visible. There are no constraints on the position of the purl/knit stitches, so a nearly infinite variety of patterns can be made. The pattern will not be apparent from every direction of viewing, since one ridge may "overshadow" another. Knitters often enjoy watching when the picture created becomes visible. The stark contrast of alternating light and dark stripes is also visually interesting. Extensions of the method include using more than two colors or using other stitches; e.g., lace knitting or cable knitting.

Viewing For an illusion artwork to be effective it has to be able to be seen from a variety of angles. Generally, illusions that are designed to be viewed from the side are best. If the illusion hangs on the wall, the viewer can move around it and see the image appear and disappear. The illusion can be viewed equally well from the right and wrong sides. An illusion designed to be seen from the bottom would have to hang very high on the wall as a viewer would probably never be able to see it while facing it directly. This type of illusion is best used on a flat surface.

Creating

Charting

Steve Plummer is a knitting artist who previously specialised in knitting wall-hangings and other items, primarily for the teaching of Mathematics. He approached illusion knitting from a mathematician's point of view and started to use a different method of charting. These charts use a square grid and are created by laying the grid over an existing image then colouring in all the stitches that need to be seen as raised bumps. Throughout the charting process it is still possible to see the original image and there is no distortion. These charts are different because they allow the four rows of the traditional method to be condensed into two different rows of squares. They can be used for creating very simple images, if required, but also allow much more flexibility to create works of art. The old method allowed areas to show either light or dark; the new method allows for intermediate shading, still using just two colours and only one colour in each stripe. The amount of shading depends on the number of stitches that are raised compared to the number that are lowered. Some of Steve's illusions are quite large. His Mona Lisa is significantly bigger than the real thing. The size is dictated by the smallest detail he wants to see, which, in a portrait, may be the centre of the eye. This then has to become one raised bump (garter stitch) on the knitting and the ridge in front of it must lie flat so you can see over it (stocking stitch). The rest of the image is built around this detail. The charting process takes perseverance, time and an amount of three-dimensional awareness. A chart can take up to 100 hours to produce. It is a process that can be learned by people with a little artistic ability and a lot of patience.

… excerpt ends here. Continue reading the full article.

Illustrations

Illusion knitting: This is a basic shadow knitting pattern created in Microsoft Excel. — This is a basic shadow knitting pattern created in Microsoft Excel.

Worked examples

Example 1 — a first encounter with Illusion knitting

Start with the simplest possible case. Write down what Illusion knitting claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, 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 Illusion knitting 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 Illusion knitting 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 Illusion knitting

In research: Illusion knitting appears in physics 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 Illusion knitting 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: Illusion knitting is common in secondary-school and first-year university syllabi. It links to neighbouring topics 21st-century neologisms, Knitted fabrics, Knitting, so understanding it makes those chapters shorter.
In everyday life: Look for Illusion knitting 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 Illusion knitting in 20 minutes

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

Frequently asked questions

What is Illusion knitting in simple terms?

Why does Illusion knitting matter?

Because it connects several physics 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 Illusion knitting?

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 Illusion knitting.