Blurry Circles

By Bonnie Roskes / Simple SketchUp Projects for Kids / February 2019 Issue

Create a dynamic optical illusion in SketchUp.

SketchUp is a free and fun program for 3D modeling. You can use SketchUp to design just about anything, from furniture to a dream bedroom to an entire city.

There is a downloadable version called SketchUp Make, which you can get here. But there is also a web-based version which works right in your Internet browser. This version is called my.sketchup, and to use it just go to www.my.sketchup.com.

Now for the project.

Look at the crisp, sharp squares in the middle of a field of blurry circles. Even though this is a 2D model, it looks as if it’s 3D – the squares seem to be floating above the circles. And if you stare a while, the circles look to be moving or shaking, while the squares stand stock-still.

Here’s how to make this in SketchUp.

After you go to the SketchUp page and launch your modeling session, here’s what you should see: a man (Josh) standing on the ground with axis lines around him. The red and green axes are on the ground, blue is for the vertical direction.

We don’t want Josh standing on our model, so click the Eraser icon or press the E shortcut key. Click on any edge of Josh to erase him.

Since the model will be drawn on the “ground,” we need to switch to a bird’s eye view – looking down on the ground from above. On the right side of the window, click the Views icon.

Then click the icon that looks like the top of a house.

You should now be looking straight down onto the red – green plane (aka the ground).

We’ll start by creating the circles. Press C for the Circle tool, and click two points to create a small circle.

The blurry effect is created by painting concentric circles with progressively darker colors. So we need to take this small circle and make several more circles from the same center. The tool for this is Offset, which you can find by clicking the Push/Pull tool and choosing Offset from the flyout.

Click anywhere on the circle, keep the mouse button pressed, and drag the mouse outward. Click when your offset circle looks like this:

For the next circle, move your mouse anywhere in the outer circle and double-click. This repeats the offset distance from the first circle.

Now we have three circles, and we want a total of 10, to be painted with 10 colors. So repeat this double-clicking seven more times, each time double-clicking on the outermost circle.

If you make a mistake and get a wrong offset, use Undo (Ctrl + Z or Cmd + Z) and start over – it’s easy to click in the wrong spot or click once instead of twice!

Now we can paint all of these faces. On the right, click the Materials icon.

On the Materials window, click the Browse icon, then open the Colors collection.

Scroll to the bottom of the list of colors, where you’ll find white and black and the eight grays in between. There are 10 of these colors, which is why we made the 10 circle faces.

One by one, paint each face, starting with white on the outside and proceeding toward black in the center.

This set of circle faces will be used to make copies, so it needs to be made into a component. To do this, press Ctrl + A (PC) or Cmd + A (Mac) to select everything. Then right-click on any selected face and choose Make Component.

Give the component any name you like, and click OK.

The completed component will have a selection box around the whole thing, which means it’s now a single object, and it is selected. Leave it selected.

Press M for the Move tool, and press the Ctrl key (PC) or Option key (Mac). The Ctrl / Option key switches from move to copy, and you only have to tap this key, not keep it pressed. For the first copy, click anywhere to start. Then move the mouse directly to the right, and click again when the copies are spaced like this:

Instead of just one copy we want several, and just after the first copy is placed is when you can set your number of copies. Type 7x, which appears in the Distance field in the lower right corner. (Don’t click in this field, just type and the numbers appear.) Press Enter, and the single copy turns into seven, making a total of eight circles.

Select everything again, and Move should still be the active tool. Press Ctrl / Option again, and place the first copy directly above or below the selected row.

Type 7x again and press Enter, to get the complete grid of blurry circles. (True, they don’t look very blurry just yet, but they will!)

Some of the circles in the middle of the grid need to be replaced with the sharp squares. Press the Spacebar to activate the Select tool, and press and hold the Shift key to select multiple objects. One by one, select the 16 squares in the middle. (You can also drag a selection window to select these, but be careful not to select any extra circles.)

Right-click on any selected circle and choose Make Unique.

To open one of these unique components for editing, the Select tool should still be active. Double-click on any of the unique components.The edited component appears in a dotted-line box, and everything else is faded in the background.

Use your scroll wheel to zoom in closely on this circle. Press R for the Rectangle tool, and tap the Ctrl / Option key to create the rectangle from its center. Click to place the center where the center of the circle is.

Move your mouse so that the rectangle will be a square, at just about the same size as the largest circle. And note that whatever changes you make to this component will be made to all of the same components.

Then use the Eraser to remove all of the circles. Only the square remains.

Use Offset again to make another square just inside. Paint the square border black.

To erase the large square face in the center, activate Select and click this face to select it.

Press the Delete key to remove this face.

The component editing is now finished. So to close the component, while the Select tool is active, click anywhere outside the component.

Now we need to make the blurry circles actually blurry. Open any of the original circle components for editing.

Activate Eraser, and while keeping the Shift key pressed, sweep your mouse over all of the circle edges. This hides the edges.

Close the component, and now all of the circles have hidden edges. But the blurry effect still can’t really be seen, because the background is still gray.

So for the last fix, click the Styles icon on the right.

In the Styles window, click the Browse icon, and open the Default Styles collection.

From this list of styles, pick anything that has painted faces, a white background, and no sky or ground color.

And that’s it! Against a white background, the circles now look blurry and the illusion looks much more clear.

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Bonnie Roskes

Bonnie Roskes has all sorts of SketchUp books at www.3dvinci.net, and co-blogs about SketchUp (and other 3D stuff) at 3Daily.net. When not glued to her computer, she can be found running (literally) around Washington, DC, or packing school lunches for her 5 kids, or napping.

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