# Excel Optical Illusions Week #21

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The Excel Optical Illusion this week is an interpretation of an award winning optical illusion. It is called Two Sinusoids. It captured 3rd place this year at the 6th Annual Illusion of the Year Contest held by the Vision Sciences Society.

A very interesting thing happened. As you know, Hui has submitted several works that I have published, and I thought I should let him know that I had already replicated this illusion in Excel, in case he was thinking of doing so. I sent him an email and he shot one straight back, saying he had done it too and was preparing to send it to me! Yikes.

As always, he did a fabulous job and so I will make both available for you to download. Here is a picture of mine:

There are six different ways for your brain to interpret this image. You can see what look a little like American footballs scrolling to the left. Look closer and you can see the whole thing turning toward you like an auger on its side. Keep looking and it will start to spin the other way.

There are three more interpretations, but I'll leave them for you to explore with the downloads and the original.

Hui and I both used the concept of multiplying frequencies to produce our respective versions, though we implemented that idea in very different ways. Both are highly iterative charts with lots of options. You can adjust the two frequencies and produce an infinite number of harmonic patterns. In my version I put a couple hundred of these interesting patterns into a gallery and you can interactively display random patterns from the gallery. It's very cool.

Both of our charts are of XY Scatter type. I used named formulas for the series. Hui used worksheet cells to do the calculations that feed his series. Both use VBA extensively.

Mine will work to a degree in older versions of Excel, but some of the interactivity will be disabled. I've tested it in Excel 2002, 2007, and 2010. It looks best on 2007, and for some mysterious reason, the animation is quicker in 2007 than 2010. From everything I've read, it is supposed to be the other way around. Since it is so fast in 2007, I added an option to include a border on the data point markers, which really slows it down. The animated GIF above was recorded with this setting on. It is much, much faster with it off.

Hui's version is for 2007+ only.

Here are the workbooks.

Daniel's version:

Hui's version:

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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)

## 1 Comment

Wow. If you aren't rich, you should be! The talent demonstrated on this blog leads me to believe that you are at the top of the heap of Excel practitioners. Definitely the most accomplished Excel artist!

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