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Geophagy: Not Your Average Eating Disorder

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We've covered pica here on the blog before -- any one of a number of conditions in which people are compelled to eat things that aren't food -- but compulsively eating urinal cakes or snacking on match heads seems a world away from today's topic, geophagy -- eating dirt. The reason is that, despite a fair amount of disagreement among experts, there are a lot of people who believe eating dirt can have some health benefits. An ingredient found in clay from the Southern US is also one of the main active ingredients in many anti-diarrheal medicines, for instance, and a Science Digest recently recommended swallowing dirt as a quick-fix antidote for people who've accidentally ingested Paraquat, a potent weed killer.

dirt cookies.jpgWhat's more, people have done it for thousands of years, from the Native Americans of California and Peru to developing nations where pregnant woman eat clay to ward off nausea and possibly aid in fetal development (lots of calcium!) and African slaves in the US, where in some parts of the old South they were nicknamed "clay-eaters." The practice continues in the rural South still, where you can buy baked, cut and processed clay dirt at flea markets. In Haiti, rising food prices have encouraged the practice, and you can buy super-cheap cookies made from dirt, salt and vegetable shortening -- more useful for warding off hunger than for their nutritive value. (Pictured at left: Haitian dirt cookies.)

Eating dirt has long been associated with iron deficiency, and while no one can say for sure whether geophagy is a cause or an effect of needing iron, iron supplements have been shown to reduce the urge. If you simply have a taste for it -- well, that's another matter.

if you feel like trying it out for yourself, you can buy some "Georgia white dirt" here, from a website that notes humanity's long and proud tradition of eating dirt, points out that said white dirt is an important additive in Kaopectate, toothpaste, Rolaids, Mylanta and Maalox, but labels their product with the following warning: "Not suggested for human consumption." That's because there are some no-duh dangers associated with eating dirt, the foremost of which is that, you know, there could be poop in it. Specifically, poop that contains parasite eggs which will give you worm infestations in your gut, or random toxins or lead or weird bacterias or a host of other nasty things. Given that, I'd much rather buy a bottle of Maalox from the store than make my own at home, but to each his own.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Name the Author Based on the Character
May 23, 2017
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