# Scary-o-graphic Projection, Thinky the Dragon, and Martin Gardner

Welcome to this week’s Math Munch!

Halloween is quickly approaching, which is why last week, Anna shared some pumpkin polyhedra. It just so happens that Justin did some pumpkin-y math of his own last year. He created a must-watch video called “Scary-o’-graphic Projection,” which was shown in the 2014 Bridges Short Film Festival. Enjoy, but don’t get too scared.

A stereographic projection sculpture by Henry Segerman.

To learn some more about stereographic projection, watch one of Henry Segerman’s videos. You’ll also get to see some of his 3D printed sculptures.  (1 2)

In other news, Oct. 21 marked the 100th anniversary of the birthday of Martin Gardner!! (previously featured here, here, and here, among others) Around this time every year people get together to do math in his honor as part of Celebration of Mind.

This year we’re featuring one of Gardner’s optical illusions. Let’s begin with a video. Meet Thinky the Dragon.

You can find printable make-your-own templates here. (There are other colors as well.) Thinky is an example of a “hollow face” illusion, many more of which can be found on mathaware.org. There you can also find this video explaining the geometry behind this illusion.

And look at this AMAZING movie trailer that one of our readers made.  Thank you Lily!!!

Can you fold this strip of 7 squares into a cube?

Whats special about this square? More than you think!

Thank you to Colm Mulcahy for his recent post on the BBC website, where Colm put together a list of 10 really wonderful problems from the hundreds that Gardner wrote about and popularized during his career. Gardner helped show the world that thinking about problems and mathematics was a really fun way to spend time. Watch the video below to learn more about Celebration of Mind events, and click here to see if there’s an event near you.  Note: You can even host an event of your own.

BONUS: I just have to mention MoSAIC for any math art enthusiasts in our audience. Around the country, small mathematical art conferences and exhibitions will go on this year. Click to learn more or find an event near you.

Munch in honor of Martin Gardner. Bon appetit!

Picture from the MoSAIC website.

### 72 responses »

1. Wow! I learned that you can make something look like it is popping out at you but really it is indented.

2. i think that it is great that people are celebrating our mind, because it is truly a great thing, and it definitely deserves our celebration.

3. I thought that the pumpkin video was cool but the t rex was creepy, if you watch the t rex in the back they move slower than the ones in the front and that is one thing I didn’t understand I kind of thought it was because the on in the front were closer to the person who made them move and that’s why or it could have just been that the ones in the back were just slower because their further away the farther i guess goes slower…to be continued.

• I think you’re right about the different speeds of the dragons. Thats called parallax. It’s like how when yiu drive down the higheay and look to the side, the far away trees move much more slowly than the ones near the car.

4. I made a flexahexagon it was fun.

5. that t-rex illusion is really creative i thought at first that they were using a wire, the pumpkin thing was a little eerie the stop motion made it so eerie tho

6. i thought the t-rex video was creepy because if you think of it as if you walked in a room and you saw that t-rex look at your every moment until you go behind it then its just like “oh how creative is that?”

7. Great tip about MoSAIC, they are having one out in Portland next year. I’ll have a chance to go 🙂

• There is a video explaining how it works. You should watch it, Saeed.

8. How did you make that look at you? It’s just amazing, and seriously it just looks at you! 🙂

9. We liked how the video used shapes to represent math applications and concept with a scary theme.

10. I learned that you can use shapes in many different ways. This is a interesting and amazing video its very cool and scary. =]

11. i learned that you make things poke out

12. I found this clip very interesting because i had never seen anything like it before.I really became found of it because it uses a scary theme to help kids understand a little bit more about how a 3 dementional object can be projected on to a plane object.

13. very cool video i saw partly how it works some of the corners were like squares so it would seem like it was looking at you when the edges were really like a square but still cool i can show this to my little brother to get him more engaged in math so very cool

• Nice observation! I hope you do show it to your brother.

14. i found the video about the pumpkins very interesting. I like that they Incorporated a math into something that we do at home for fun. At the beginning of the video i didn’t really understand what the video was about but later in the video i thought of how to include math into it. I also liked that they included the Halloween theme into it.

15. i think this video was cool how they made scary things out of shapes and think other people will watch

16. I really liked how the knifes made the triangles on the pumpkin.I thought it was very interesting although it did scare me a little.

17. i found this clip very entertaining because it uses a scary theme too make it more interesting and it shows how a 3 dementional object can be turned into a plane object!

18. Very interesting. I feel that many people did not realize that when you put the light in that it was actually creating a shadow like figure on the ground. But still, very cool!

19. i like how they cut the shapes in the pumpkin but then when they put the light in the pumpkin and then it makes a totally different shape

20. this video was good because i liked how they were cutting the pumpkin and they made cool shapes

21. It was pretty cool how the dragon was looked like it was moving its head to look at you.Although it was just bent.

22. I thought the T Rex video was really cool but a little creepy and i will surely try this at home

23. i think the pumpkin video was really fun and cool because it made the pumpkin look awesome

24. it is good that we celebrate our mind with out our minds we would know nothing. Because we need our knowledge for everything.

25. during the video with the alligators and the optical illusions i was wondering how do they do that it was also creepy when watching it because i thought do the heads actually follow the camera or not but then at the end it shows that the head was actually was just flat and its like i would’nt think that’s what it is

26. Oh my gosh that was so cool and creepy my favorite part is when they show you how the aligators head moves

27. This clip was very interesting because i never knew that all this was related to math, its so cool that we do a lot of things each day that revolve around math but we don’t even know it.

28. I thought the pumpkin video was so cool!!!!!I loved how the put a light in the pumpkins too make them look 3D.

29. My favorite Part was when you shun the light inside the pumpkin and it made a shadow on the wall.I also liked the scary theme it was really cool!!!!!

30. Very cool video mathmatic shapes and pumpkin varving fun all into one!But it was a very cool video could show it to my brother to make him more engaged in shapes very cool video with the scary theme

31. I really enjoyed this video because at first i had no idea what it meant by optical allusion because it looked like it was moving. I admit i didn’t believe what it said, i didn’t trust them, but once it showed how it was an optical allusion i figured out that they put these videos up on this web sight not to try and trick us but to help us learn, so i learned they don’t lie when they say optical allusion.

32. I thought the video was very interesting and had a lot of cool shapes and designs that had to do with math and science. It was very fun and interesting to watch. A little bit scary as well for me.

33. I wonder how long it took them to carve the pumpkins and how they figured if u light up the inside of the pumpkin it makes cool shadows on the outside.

34. I thought the T-Rex video was quite interesting and fun to watch and I wonder how they made the head move and turn side to side.

35. Nice video! this made me realize that sometimes your eyes sometimes play tricks on you.But i wonder what other things your eyes cant seem to really see.

36. I thought that the pumpkins that turned into different 3d shapes was interesting because i hav learned something in that video. i have never known about those names of shapes

37. The video for the pumpkins was cool also what i learned was you can make shapes and the video interesting.

38. I like how they did so many things with pumpkins, and how cool you could make it look. Its very creative and awesome, lol, i just wish i could do stuff like that.

39. Its amazing how they did the T-Rex illusion, its very fascinating, and……I don’t even know what to say. That is how amazing it is.

40. In that video “Celebration Of Minds” its cool how many things you could that looks awesome and is so creative.

41. OMG!!!!!I am still totally freaked out about the t-rex thing.How did the person do it,its just so cool

42. this video is really cool thouth i didnt know what it meant at first about the optical illusion because it looked like it was moving, at first i thouth that it was all done by computer but as he showed the steps i understood that they trying to make us learn which its really cool

43. I really enjoyed the T. Rex video illusion it was a really fun video to watch.

44. i think this is really cool to make a figure out of templates and make it look like its moving.

45. Wow! I learned that you can make something look like it is popping out at you but really it is indented.

• You shouod try to print one out and build it. Seeing it might help.

46. I really liked the Dragon named Thinky. It mystified me to figure out that he was just an optical illusion, being a folded piece of paper. My teacher has three and showed us how the optical illusion worked, the word for it was mono optical? Meaning that it worked to see it with one eye covered easier than with two eyes. That made me think, having one eye is easier to deceive, two eyes creates two vantage points which shows the illusion.

47. I really liked how you were able to carve the pumpkin into a octahedron. How did you carve the pumpkin so well? And what made it an octahedron? Octa mainly means 8 like an octagon, so what 8 parts made it an Octahedron?

48. in the pumpkin video, if you were to do a bunch of small round circles would the circles become warped the farther away the got from the pumpkin? i would imagine it to be so but in the picture right under the video it didnt appear that way with hexagons

• I think I agree with you. Take a look at Henry Segerman’s stereographic projection videos. He has one thats made of circles ans he talks about how circles act when theyre projected.

49. in the t-rex video,i thought it was really cool how until you were shown how it works it really does tangle with your brain. at first i thought it was the angle/perspective from witch a flat surface was being viewed that changed how it looks, like the portrait of the old king that can only be viewed correctly at an angle.

50. The tyronosorus rex video was weird and creepy. I didn’t know that you could have a backwards facing half rectangle look Iike a forwards facing rectangle. It is a really interesting design.

51. I thought the T-rex thng was really creepy and interesting to watch. I wonder how they did it