For Better Photogrammetry, Just Add A Donut

If you don’t have access to a 3D scanner, you can get a lot done with photogrammetry. Basically, you take a bunch of pictures of an object from different angles, and then stitch them together with software to create a 3D model. For best results, you need consistent, diffuse lighting, an unchanging background, and a steady camera.

Industrial designer [Eric Strebel] recently made an Intro to Photogrammetry video wherein he circled an object taking photos with his bare hands. One commenter suggested a different method: build a donut-shaped turntable that circles the object, which sits on a stationary platform. Attach the camera to the donut, counterbalance the weight, and Bob’s your proverbial uncle. [Eric] thought it was a brilliant idea (because it is), and he built a proof of concept. This is that video.

[Eric] can move the camera up and down the arc of the boom to get all the Z-positions he wants. The platform has a mark every 10° and there’s a pointer in the platform to line them up against for consistent camera positioning. He was pleasantly surprised by the results, which we agree are outstanding.

We always learn a lot from [Eric]’s videos, and this one’s no exception. Case in point: he makes a cardboard mock-up by laying out the pieces, and uses that to make a pattern for the recycled plywood and melamine version. In the photogrammetry video, he covers spray paint techniques to make objects reflect as little light as possible so the details don’t get lost.

If you prefer to rotate your objects, get an Arduino out and automate the spin.

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No Microcontroller In This Vending Machine, D’oh!

You might think that a microcontroller would be needed to handle a vending machine’s logic. For one thing, only the correct change should activate them and the wrong change should be returned.  If the correct change was detected then a button press should deliver the right food to the dispenser. But if you like puzzles then you might try to think of a way to do with without a microcontroller. After all, the whole circuit can be thought of as a few motors, a power source, and a collection of switches, including the right sized coin.

That’s the way [Little Puffin] approached this donut dispensing vending machine. What’s really fun is to watch the video below and wonder how the logic will all come together as you see each part being put in place. For example, it’s not until near the end that you see how the coin which is a part of the circuit is removed from the circuit for the next purchase (we won’t spoil it for you). Coins which are too small are promptly returned to the customer. To handle coins which are the right size but are too heavy, one enhancement could be to make them fall through a spring-moderated trap door and be returned as well. We’re not sure how to handle coins which are the right size but too light though.

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Donuts Of ShmooCon

This weekend is ShmooCon, a hacker convention held in Washington DC. Brian Benchoff and I will be there, both of us for the first time. We’d love your input on what talks look the most interesting. Check out the schedule of speakers, then leave a comment below to let us know which talks you think we should cover.

It’s great hearing the big presentations, but I find a lot of times great hacks can be found in smaller venues, or just by walking around. Two examples from 2015 DEF CON: the best talk I sat in on had about 10 people spectating in the IoT village, and I had a great time trying to track down everyone who had an unofficial hardware badge. If you’re at ShmooCon and have something to show off, please find us (@szczys, @bbenchoff)!

On Saturday join us for a Hackaday meetup in the lobby of the Washington Hilton. ShmooCon is well-regarded for the quality of its “lobby-con”, what better place to gather? Look for the Hackaday crowd starting Saturday 1/16 at 8:45am. We’ll bring the donuts, and some swag like Hackaday Omnibus Vol. 02 and of course, some Jolly Wrencher stickers.

Solar Cells From Donuts And Tea

It sounds unbelievable, but it is true. You can harvest most of what you need for a simple solar cell from powdered donuts and tea. Powdered donuts have nanoparticles of titanium dioxide which is a “high band gap semi conductor”.  This means that it can be used to make solar cells. The tea is simply used to dye the material so it can pick up the visible spectrum. The process is a bit too involved to be something you would just toss together in the field, but it’s cute nonetheless.