4 ms·

Erik Demaine's Folding and Unfolding Page (2010)

30 points by sytelus 8y ago

toolslive 8y ago
Just reading the title, I could have sworn this was about functional programming. So I clicked, was surprised it wasn't but still read on as it's quite interesting.
quelsolaar 8y ago
Ive been working for over a year writing a algorithm for unfolding 3D models (http://www.ministryofflat.com http://www.ministryofflat.com) for texturing. Unfolding 3D models is an almost unknown task that is done mostly by hand by 3D artists. Game developers spends huge sums of money on this.
- no-s 8y ago
  that's cool. Seems like it would be useful in other fields. for example I would like to make 3d objects larger than cnc machines tool workspace - eg cnc router, 3d printer, or mill. So if I understand this correctly, the result is a .obj file with cut out surfaces nested such that the average normal is normal to the flat surface? Could it be constrained so that for example so as to split by height (z)? How should I split out the surfaces? Are the vertex normals included in the output (useful for fitting physical parts along edges)?
  - quelsolaar 8y ago
    The source is about 700k of C, so there are all kinds of algorithms for folding and space optimizing, but out of the box it would not work too well. 3D artists have some very particular ideas of what makes for good unwrapping. In general they dont want stretching, but there are a bunch of special cases where "the right kind" of stretching is a good thing. My algorithm tries to implement all these special cases. (that are over 20 different passes that each tries to solve a specific type of geometry). For CNC its actually much simpler, since the rules of what is and isn't permissible are much simpler.
    - no-s 8y ago
      don't worry, CNC also has lots of special cases. but thanks for getting me thinking about the math.
mehrdadn 8y ago
Worth noting: he teaches (or taught) advanced data structures at MIT. It's probably worth looking into... I didn't manage to find an equivalent to his course anywhere when I was looking around a few years ago.
- cntlzw 8y ago
  Yes! Highly recommended! I watched some of them on YouTube. Not only is Erik a highly skilled mathematician he is also a wonderful lecturer. Hope his students acknowledge what a great teacher he his.
  - Cursuviam 8y ago
    It was a wonderful class! When I took it, the class sessions were basically open problem solving sessions involving said advance data structures. Apparently, the class leads to at least 2 or 3 published papers whenever its held.
- basil-rash 8y ago
  I believe he teaches it every other fall. He last taught it fall 2017, so fall 2019 would be the next.
dpflan 8y ago
If you found this interesting or find origami interesting, I recommend the documentary Between the Folds. Demaine is one of many origamist featured. > Official Website: https://www.betweenthefolds.com/ https://www.betweenthefolds.com/ > Looks like if you have Amazon Prime you can stream it: https://www.amazon.com/Between-Folds-Vanessa-Gould/dp/B003DQ6I2C/ https://www.amazon.com/Between-Folds-Vanessa-Gould/dp/B003DQ... Enjoy!
bookofjoe 8y ago
"Erik Demaine, the genius that plays for a living" https://youtu.be/g4GsDJwH2yA https://youtu.be/g4GsDJwH2yA

30 points by sytelus 8y ago

Just reading the title, I could have sworn this was about functional programming. So I clicked, was surprised it wasn't but still read on as it's quite interesting.

quelsolaar 8y ago

Ive been working for over a year writing a algorithm for unfolding 3D models (http://www.ministryofflat.com http://www.ministryofflat.com) for texturing. Unfolding 3D models is an almost unknown task that is done mostly by hand by 3D artists. Game developers spends huge sums of money on this.

no-s 8y ago
that's cool. Seems like it would be useful in other fields. for example I would like to make 3d objects larger than cnc machines tool workspace - eg cnc router, 3d printer, or mill. So if I understand this correctly, the result is a .obj file with cut out surfaces nested such that the average normal is normal to the flat surface? Could it be constrained so that for example so as to split by height (z)? How should I split out the surfaces? Are the vertex normals included in the output (useful for fitting physical parts along edges)?
- quelsolaar 8y ago
  The source is about 700k of C, so there are all kinds of algorithms for folding and space optimizing, but out of the box it would not work too well. 3D artists have some very particular ideas of what makes for good unwrapping. In general they dont want stretching, but there are a bunch of special cases where "the right kind" of stretching is a good thing. My algorithm tries to implement all these special cases. (that are over 20 different passes that each tries to solve a specific type of geometry). For CNC its actually much simpler, since the rules of what is and isn't permissible are much simpler.
  - no-s 8y ago
    don't worry, CNC also has lots of special cases. but thanks for getting me thinking about the math.

mehrdadn 8y ago

Worth noting: he teaches (or taught) advanced data structures at MIT. It's probably worth looking into... I didn't manage to find an equivalent to his course anywhere when I was looking around a few years ago.

cntlzw 8y ago
Yes! Highly recommended! I watched some of them on YouTube. Not only is Erik a highly skilled mathematician he is also a wonderful lecturer. Hope his students acknowledge what a great teacher he his.
- Cursuviam 8y ago
  It was a wonderful class! When I took it, the class sessions were basically open problem solving sessions involving said advance data structures. Apparently, the class leads to at least 2 or 3 published papers whenever its held.
basil-rash 8y ago
I believe he teaches it every other fall. He last taught it fall 2017, so fall 2019 would be the next.

dpflan 8y ago

If you found this interesting or find origami interesting, I recommend the documentary Between the Folds. Demaine is one of many origamist featured. > Official Website: https://www.betweenthefolds.com/ https://www.betweenthefolds.com/ > Looks like if you have Amazon Prime you can stream it: https://www.amazon.com/Between-Folds-Vanessa-Gould/dp/B003DQ6I2C/ https://www.amazon.com/Between-Folds-Vanessa-Gould/dp/B003DQ... Enjoy!

bookofjoe 8y ago

"Erik Demaine, the genius that plays for a living" https://youtu.be/g4GsDJwH2yA https://youtu.be/g4GsDJwH2yA