Penrose Triangle Illusion

by chylld, published

Penrose Triangle Illusion by chylld Feb 19, 2011

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!! New version penrose5.stl with a couple of wayward vertices fixed !!

This is a 3D-printable version of the Penrose Triangle illusion, based solely on the 1934 design painted by Swedish artist Oscar Reutersvärd. The design also appeared on Swedish postage stamps in the early 1980s.

I created this 3D design entirely from scratch using the process outlined in the "Instructions" section below. This work is based solely on Oscar Reutersvärd's design, although some elements are inspired by the Hollow-Face illusion discovered many decades (if not centuries) ago.

This model contains a number of notable improvements over previous 3D representations:

1) It is parallax-corrected for a viewing distance of 40cm, i.e. it will look exactly like Oscar Reutersvärd's design, with cubes lining up on all 3 sides simultaneously. This is a great visual improvement over previous versions, which only lined up on 2 sides simultaneously.

2) It has been resized (to 99.43 x 99.65mm) to make maximum use of the Makerbot build envelope.

3) The top edges are now tapered so as to make the most of your printer's capabilities. The better your printer, the sharper the edges will be.

4) I own the copyright to this 3D design, and hereby distribute it under the "Attribution/Non-Commercial/Share-Alike" licence for all non-profit parties to print, improve and share.


Simply print! No support required.

NB: I have uploaded a new penrose4.stl file, which has better poly orientation to ensure that the walls build up gradually.

There is also now a new penrose4_braced.stl file which includes bracing to help keep the blocks in the right position during the first half of the print!

You can create your own Penrose Triangle illusion very easily by following these steps in your favourite 3D software. A photo has been attached for each step.

1) Create an image plane containing the image you are trying to portray. Then create a camera at a suitable viewing distance from the image plane (e.g. 40cm)
2) Create a cube, rotate it so it matches a cube in the image, delete the top 3 faces and then duplicate it 8 times. Lay them out roughly.
3) Viewing from the camera created in step 1, pull the vertices in X and Y until they line up with the image. This corrects for parallax error since we are working from the intended viewpoint perspective, and not an orthographic view.
4) Cut out the bits you don't want, referring back to the image if you need to. Once done, stitch everything together into one surface.
5) Extrude the stitched surface up or down and then widen the bases of each cube if you want. Done!

Making your own 3D Penrose Triangle model clearly isn't rocket science. In fact, it would make a very good practice exercise for first-year 3D art/design students!

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It took me quite a few tries to get this to print properly, even scaled up to 150%, as I had ongoing issues with PLA warping up even with cooling. I wound up resolving the issue by switching from Slic3r to Cura. In Cura, I set the wall thickness to 0.5mm (I have a 0.5mm nozzle on my RRP Mendel), and also needed to use a brim to keep the print on the bed. This is more a limitation of my printer, but I thought I'd mention in case anyone else is trying to solve the same issue.

Thank you!

I am not a techy, I am a quilter. I went searching the internet for 3-d illusions and holy wow!!!! This blows my mind..... the idea that it can print in 3-d blows my mind again.

I am going to try to re-create the 3-d illusion in 2-d fabric ... if it works I will post a pic!

chylld - in reply to Guest

Maria that would be great - it should still work to a large extent :) Post the pic here when you're done!

Excellent rendition... magnanimous of you. Thank You.

where can I buy one of these!

Does he also own the copyright to the Star of David created in the middle of his 3D printed Penrose Triangle Illusion?

I know this is a late post, and although this sounds odd, the answer to your question is 1, no there is no Star of David in his design so 2, yes, he technically owns the Star of David. There is, by chance, a star of David at the center of the design of you tilt it a certain way. Think of the situation as you folding origami, and making a, say cross with your folds. This is made is Christianity's symbol, but only when you tilt your paper do you find the symbol. Therefore, chance overtakes the legal system, so there is no Star Of David in the design, it is only in your mind, almost like an optical illusion. On that sense, he owns your vision of the optical illusion, so yes, he owns [the file, not your print] the Star of David, science it is part of his design. If someone has any corrections for this, feel free to respond, but I believe I am right in saying that there is no Star of David, but he owns your image of the Star of David. Thanks for reading.

thats public domain.

Will someone add dice pips on this (like this http://www.moillusions.com/2007/05/impossible-dices-triangle-illusion.html)http://www.moillusions.com/200... and print me a copy so I can cast it in bronze? Print two and I'll cast one for the person who prints it also. I'm getting quite good at the bronze casting so it won't look shoddy. Contact me at @johngomm on twitter if you can help me out.

Awesome! Thanks a lot for sharing this great thing!

Made a short video of my print: http://post.ly/1fUFqhttp://post.ly/1fUFq

Thank you for your work!

I will have to have a go at printing this one in the morning as well.

Cool, thank you!

Anyone knows the weight of the printed model and can be so kind to post it?

chylld - in reply to caru

Mine weighs 22 grams...

caru - in reply to chylld

Thank you... it's great to know that a thing that costs so much (70
€, but probably it costs 20/40 € to the seller) on shapeways, we can print for less than one euro. And this is original and even better! ;)

I sense floaty magnet penrose triangle coming.. :

@nathan7 ...mmh cool idea :)

Love it, just firing up my ToM and going to print it with some green ABS, I post a pic when it's done.

Thanks for sharing your 2D to 3D mapping work flow!

Thanks for the support guys, it means A LOT.

I will have something even better for you all soon :)

Everyone should Flatter the hell out of this design and it's Author. I just did!!

Very nice. I'll be printing one this morning.