This is the illusion I'm trying to recreate.

Moving Tunnel Optical Illusion

As seen below I've tried to use the blend tool but the increments are even which ruins the perspective. I did see a tutorial (time stamped link) where you can manipulate the spine and use the handles to adjust the spacing but it doesn't seem possible with this particular shape. This method doesn't seem to allow the necessary control to maintain the perspective.

Moving tunnel outline

As seen below another method I've looked into is using the scaling method and shrinking it by a % with each step but the outside shape is different from the inside. The inside doorway shape is a lot narrower where the outside is much wider.

Shape comparison

I'd greatly appreciate any help as I've run out of ideas.


2 Answers 2


You can make the perspective automatically. Make a 4 anchor point version of your cave profile. Extrude it with effect > 3D > Extrude and bevel. Have only a stroke but no fill. It generates a shell which has visible interior. The colorful pattern (much simpler than yours) is the one that I'm going to place on the surfaces of the cave.

enter image description here

The arc must NOT have any anchors except at the ends, so you have total 4 anchor points. More of them splits the surfaces in a complex way which makes art mapping difficult.

The magenta horizontal line is drawn to have a guide for making the curve handles equally high.

The extruded shape seen from aside and rendered with shading:

enter image description here

Straight on the face view (all rotation angles =0) with perspective is your wanted view. The shading is removed and my "artwork" is mapped onto the interior roof surface:

enter image description here

The "artwork" is dragged into the Symbols collection. That makes it available in the Map Art dialog. Shading is removed to preserve original artwork colors.

There's quite many surfaces. If you are lucky Illustrator makes only 4 separate pieces of the interior to be covered. I was that lucky.

There's no waterproof control over how many different surfaces you must cover separately. A slightest irregularity or more anchors splinter easily the surfaces so that one must cover more than 4 slices.

In the next image the same artwork is mapped onto the rest of the interior surfaces.

enter image description here

Learn the details of the 3D effect in Illustrator User's Guide. Use Object > Extrude Appearance to fix the effect and make manual edits possible.

You need to ungroup all several times, remove 4 clipping masks and ungroup again all until every piece is free and separately accessible. Groups are actually useful because they give some protection against moving the pieces apart accidentally without noticing.


What I would do...
(This is quick and a tad sloppy.)

Start with a few primary shapes.
The stacking order of the shapes is important.
Shapes are stacked largest to smallest.

enter image description here

Then Object > Blend > Make and Object > Blend > Blend Options

enter image description here

I probably could have put one more shape between the largest and the next size down, but this still works.

Then I add the perspective lines...

enter image description here

Note that this all does not exactly mimic the spacing, and divisions in your original. It's an approximation to get the same general set up. The original has some slight curves to the perspective. This, while possible presents a challenge too great to try and detail here.

Now I'd set up a palette of colors...

enter image description here

These are ordered the same as the color order in the image. From outside in, the colors are in this order for every section of the image, then repeated.

Select the Blend and choose Object > Expand and when the window pops up, just check Object and click OK. (You can make a copy of the blend object first, in case you want a backup of it as a live blend)

enter image description here

Then I'd select all the paths and set the stroke to None via the Stroke Panel.

I'd then grab the Live Paint Bucket Tool, click once to convert the paths to a Live Paint Object....

And from here,it's a matter of using the arrow keys and clicking with the mouse. Click once to fill a section with a color, tap an arrow key to move to the next color, click again, tap an arrow, click again, repeat...

enter image description here
(The gif makes yellows kind a look the same. But they are the 2 yellows from the color palette above.)

I didn't do the entire thing, but you can see below, even a bit incomplete, the illusion works. From here it's just a matter of refining things overall and being a bit more precise with line placement and the blend steps.

enter image description here

Ultimately, it's the pattern of colors in perspective that creates the illusion. You really don't have to precisely match your original image.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.