How to makethe animated optical illusions

We showed how animated optical illusions appear to move on the "What is" page

Now, let's see how this mechanism is used in animated optical illusions by actually making one.

We'll create a two-frame animated optical illusions using two illustrations.For animated optical illusions, you need a striped moving sheet and an Underlying Illustration.

How to make the Striped Moving Sheet

First, let's make the striped moving sheet.

For a two-frame animated optical illusions, you need a striped moving sheet with a 1:1 ratio of black stripes to clear stripes. For example, if the black stripes are 5mm wide, the striped moving sheet should have 5mm intervals of black and clear stripes.

The width of the stripes depends on the illustrations. You need to adjust the width for complex and simple illustrations.

The illustrations hidden by the striped moving sheet must have continuity. (For more details, please refer to the "What is" page.)

Narrower stripes allow the visible part to have continuity, making it easier to recognize the illustration as a whole.

This also means that it will instantly change to the next frame. With a 5mm striped moving sheet, the frame changes with a 5mm horizontal movement, but with a 1mm striped moving sheet, the frame changes with just a 1mm movement, making it hard to see.

Conversely, wider stripes disrupt the continuity of the visible part, making it harder to recognize the illustration as a whole. The frame change slows down as more horizontal movement is needed, reducing the sense of motion.

Neither is perfect. Narrow stripes and wide stripes both have problems that make the animation less smooth.

You need to make a striped moving sheet with the best stripe width and number of frames by thinking about the people who will use it and the content of the illustrations. Let's try different options and see what works best.

How to make the Underlying Illustration

First, overlay the striped moving sheet on the illustration for the first frame. The part of the illustration visible through the clear stripes is the part needed for the first frame. Extract this part.

Using image editing software like Photoshop or Illustrator makes this process easy. In the past, this was done using tracing paper, which was very tedious.

For clarity, we have changed the colors of the first and second frame illustrations in this example.

When you actually make it, it's better to use the same color for the illustrations to make them easier for the brain to recognize as the same object. Remember the factor we mentioned on the "What is" page: the visible part has continuity.

We now have the illustration needed for the first frame. This means we have created an illustration where only half of the original illustration is visible.

You might have already guessed it. This illustration makes use of the second brain function, which we mentioned on the "What is" page. The second function is "When part of an object is hidden from view, the brain uses experience and knowledge to fill in the hidden parts and instantly recognize the whole object."

Given the right factors, such as experience and knowledge, the brain will fill in the hidden parts when using a striped moving sheet. Therefore, we made an illustration that omits the hidden parts.

Let's try overlaying this illustration with the striped moving sheet. Click on the illustration below to display the striped moving sheet. You should see a person and the ball appear.

Now, try dragging the striped moving sheet sideways. The person and the ball disappear, leaving only the striped moving sheet. It's obvious, isn't it? After all, the illustration omits the hidden parts.

The clear parts of the striped moving sheet now show the parts hidden in the first frame. Make the second frame illustration visible in these parts.

Make the illustration needed for the second frame using the same method as for the first frame.

Overlay the striped moving sheet on the illustration for the second frame and shift the striped moving sheet by the width of the stripes. The part of the illustration visible through the clear stripes is the part needed for the second frame.

For example, if the stripes are 5mm wide, shift the striped moving sheet by 5mm. Extract the part visible through the clear stripes.

Finally, we combine the illustrations extracted for the first frame and the second frame. Since they are offset by the width of the stripes, they should form a single illustration without overlapping each other. Underlying Illustration is now complete.

Click on the illustration below to display the striped moving sheet, and slowly drag it sideways. The illustrations for the first and second frames will be displayed alternately.

If you move the striped moving sheet quickly, the illustration should appear to be moving.

This is a function of the brain, which we mentioned on the "What is" page, where "the brain recognizes similar objects seen consecutively as the same object and fills in the gaps between them."

The two-frame animated optical illusions is now complete.

The Relationship Between the Number of Frames and the Striped Moving Sheet

How can we make a three-frame animated optical illusions?

First, make a striped moving sheet with a 2:1 ratio of black to clear stripes and three illustrations.

Then make an Underlying illustration the same way as for the two-frame animated optical illusions.

When the first frame illustration is visible, the second and third frames need to be hidden, so the clear part is 1, and the black part is 2.

Once you understand how it works, your perspective on animated illusions might change.

There are many other toys that use the brain's functions, such as optical illusions, trick art, and trompe l'oeil. If you're interested, search for these topics and explore other websites.

Thank you for reading to the end.