Excel Optical Illusions Week #22

This week's Excel Optical Illusion is called Perpetual Collisions. The original work by Arthur Shapiro and Emily Knight was a 2008 finalist at the Best Illusion of the Year Contest, held by the Vision Sciences Society.

Here is the description of the Perpetual Collisions Illusion directly from their entry:

In the perpetual collisions illusion, the pink and the yellow columns seem always to be headed towards (or away from) each other, but they never meet (and they never grow further apart). Actually, the colored fields are completely stationary; an appearance of motion is generated by the spinning black and white diamonds located alongside the columns. Click on the button to add diagonal bars and remove the edges from opposing diamonds. Notice that the information at the edges makes the colored fields move diagonally, yet when the bars are not there and all the edges are visible, the fields move horizontally.

My Excel version (pictured in the animated GIF above) seems to work well in Excel 2002, 2007, and 2010, although I had to add more formulas just to support Excel 2002.

The chart is an XY Scatter type using inserted Excel shapes as the markers. When using compound shapes as markers, it is very frustrating because Excel changes the shape ever so slightly when copied to the chart's data series. I experienced the exact same frustration when I was crafting celtic muse and those tiles are much simpler than these. It took quite a bit of trial and error to get them working as well as they are. It's not perfect, but it's close enough! I've included the tiles below the chart if you want to have a whack at it.

All of the series are fed from named formulas. The formulas that have a name like frame_[n]_y_coords are there only because Excel 2002 required them in order to not display a frame's markers when that frame was out of scope. So adding these names enabled the chart to work in all versions. Likewise all the -100 values in the formulas are a requirement of Excel 2002.

The arrays for the series use two different techniques in their construction. There are four frames in the animation. The frame marker series array is constructed by multiplying together two constant arrays and then we just use INDEX to get the appropriate column for each frame. The diagonals series on the other hand is created by a completely different technique. Can you figure it out?

For such a simple display, this is a pretty advanced Excel chart and well worth your study time.

So what is your impression of the Perpetual Collisions Illusion chart?

Here is the file.

.xls

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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:

- Bulging Checkerboard

- Egg Shadow

- Eye Jitter

- Stereokinetic Illusion