# Excel Optical Illusions Week #25

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This week's Excel Optical Illusion is called the Stepping Feet Radial Illusion.

As Michale Bach describes this illusion on his page that inspired me...

... Observe the move ment of blue and yellow patch es ('feet'). Whenever the [radial] grid is visible, the feet seem to step out of phase, while in reality their movement is always par alĀ­lel. Like tiny feet going tip-tap-tip-tap... The effect is more pronounced if one does not look directly on to the feet.

This project started out as a chart, but I was not happy with the outcome so I changed it to animated shapes. The spokes image in the background was creates with a Radar chart. I left the named formulas for the series in the name manager if you would like to look at them.

The "feet" are shapes grouped together with an invisible line that stretches all the way across the circle, centered on the circle's center. For the animation I use VBA to rotate this grouped shape.

At every 12% of the way around the circle, the VBA toggles the visibility of the radial grid. When the grid is not visible it is obvious that the feet never shift but are locked in parallel motion.

Here is the file.

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Why do I share these optical illusions? The techniques that are used to make them, when mastered, can be used in many other Excel projects, in charting, formula crafting, and formatting. Learn them. They will aid you on your journey to become an Excel Hero.

Here is a list of other Excel Optical Illusions here at Excel Hero:

And here's a list of other animated charts on Excel Hero:

- Excel, A Presentation Platform (Number Spiral)
- Lilac Chaser (Optical Illusion)
- Stereokinetic (Optical Illusion)
- Illusory Contours (Optical Illusion)
- Breathing Square (Optical Illusion)
- Enigma (Optical Illusion)
- Two Sinusoids (Optical Illusion)
- Perpetual Collisions (Optical Illusion)
- Freezing Rotation (Optical Illusion)
- Reverse Spoke Illusion (Optical Illusion)
- Stepping Feet Radial Illusion (Optical Illusion)

## 1 Comment

This is an interesting one Daniel.

Apart from the aparent differences in the movement of the inner and outer bar, The small bars look like they move at different speeds in different locations around the circle.

So I turned off the background and then left it on and then cycled it as per your file, and in all 3 cases the bars took 30 seconds on my system to do a full lap.

I particularly like your
Sheet1.Shapes(1).Visible = Not Sheet1.Shapes(1).Visible
line.
I don't use "Not" enough.

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