Fabricate Your Own Tabletop Gaming Props

July 14, 2017 by John Baichtal 13 Comments

Delve into the mysterious world of tabletop roleplaying games. Warhammer Fantasy Roleplay, Shadowrun, Pathfinder, Ars Magica, Vampire, whatever gets your dice rollin’ — metaphorically in the case of a diceless system. This might very well be your daddy’s D&D. If you’re not a gamer, you’re certainly familiar with the concept. People sit around a table pretending to have an epic adventure, often adding a random element with the help of dice. A map is often displayed on the table, sized for figures that show the various heroes and villains.

As a person with access to a variety of CNC machines I find myself wanting to create things to make gameplay more fun. I want to build a scale castle and have a siege. I want to conduct a ship-to-ship battle with wooden ships built to scale. But I also think smaller. What is something I could make that would help us every day? Say, a box for dice. Not every project needs to be the dragon’s lair.

It turns out a lot of other folks have been thinking about the same thing.

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A 3D Scanner That Archimedes Could Get Behind

July 14, 2017 by Dan Maloney 48 Comments

3D-scanning seems like a straightforward process — put the subject inside a motion control gantry, bounce light off the surface, measure the reflections, and do some math to reconstruct the shape in three dimensions. But traditional 3D-scanning isn’t good for subjects with complex topologies and lots of nooks and crannies that light can’t get to. Which is why volumetric 3D-scanning could become an important tool someday.

As the name implies, volumetric scanning relies on measuring the change in volume of a medium as an object is moved through it. In the case of [Kfir Aberman] and [Oren Katzir]’s “dip scanning” method, the medium is a tank of water whose level is measured to a high precision with a float sensor. The object to be scanned is dipped slowly into the water by a robot as data is gathered. The robot removes the object, changes the orientation, and dips again. Dipping is repeated until enough data has been collected to run through a transformation algorithm that can reconstruct the shape of the object. Anywhere the water can reach can be scanned, and the video below shows how good the results can be with enough data. Full details are available in the PDF of their paper.

While optical 3D-scanning with the standard turntable and laser configuration will probably be around for a while, dip scanning seems like a powerful method for getting topological data using really simple equipment.

[wpvideo xx88I1SN]

Thanks to [bmsleight] for the tip.

Books You Should Read: The Bridge

July 14, 2017 by Adam Fabio 95 Comments

A few weeks ago, Amazon’s crack marketing AI decided to recommend a few books for me. That AI must be getting better because instead of the latest special-edition Twilight books, I was greeted with this:

“The asteroid was called the Hand of God when it hit.”

That’s the first sentence of The Bridge, a new Sci-Fi book by Leonard Petracci. If you think that line sucks you in, wait until you read the whole first chapter.

The Bridge is solidly in the generation ship trope. A voyage hundreds or even thousands of years long, with no sleep or stasis pods. The original crew knows they have no hope of seeing their destination, nor will their children and grandchildren. Heinlein delved into it with Orphans of the Sky. Even Robert Goddard himself discussed generation ships in The Last Migration.

I wouldn’t call The Bridge hard Sci-Fi — and that’s perfectly fine. Leonard isn’t going for scientific accuracy. It’s a great character driven story. If you enjoyed a book like Ready Player One, you’ll probably enjoy this.

The Bridge Is the story of Dandelion 14, a ship carrying people of Earth to a new planet. At some point during the journey, Dandelion 14 was struck by an asteroid, which split the ship in two. Only a few wires and cables keep the halves of the ship together. The crew on both sides of the ship survived, but they had no way to communicate. They do catch glimpses of each other in the windows though.

Much of the story is told in the first person by Horatius, a young man born hundreds of years after the asteroid strike. Horatius’ side of the ship has a population of one thousand, carefully measured at each census. They’ve lost knowledge of how to operate the ship’s systems, but they are surviving. Most of the population are gardeners, but there are doctors, cooks, porters, and a few historians. At four years old, Horatius is selected to become a gardener, like his father was before him. But Horatius has higher aspirations. He longs to become a historian to learn the secrets of the generations that came before him and to write his own story down for those who will come after.

Horatius sees the faces of the people on the other side of the ship as well. Gaunt, hungry, often fighting with knives or other weapons. A stark contrast to the well-fed people on his side of the vessel. The exception is one red-haired girl about his age. He often finds her staring back at him, watching him.

Horatius might have been chosen as a gardener, but he’s clever — a fact that sometimes gets him in trouble. His life takes an abrupt turn when the sleeping ship awakens with an announcement blaring “Systems Rebooting, Ship damage assessed. Reuniting the two halves of the ship and restoring airlock, approximately twenty-four hours until complete.”

The hardest part of writing a book review is not giving too much away. While I won’t tell you much more about the plot for The Bridge, I can tell a bit about how the book came about. You might call this book a hack of the publishing system. Leonard Petracci is also known as leoduhvinci on Reddit. The Bridge started life as Leonard’s response to a post on /r/writingprompts. The prompt went like this:

After almost 1,000 years the population of a generation ship has lost the ability to understand most technology and now lives at a pre-industrial level. Today the ship reaches its destination and the automated systems come back online.

Leonard ’s response to the prompt shot straight to the top, and became the first chapter of The Bridge. Chapter 2 followed soon after. In only a few months, the book was complete. Available on Reddit, and on Leonard’s website. The Bridge is also available on Amazon for Kindle, and on paper from Amazon’s CreateSpace.

The only real criticism I have about The Bridge is the ending. The book’s resolution felt a bit rushed. It would have been nice to have a few more pages telling us what happened to the characters after the major events of the book. Leonard is planning a sequel though, and he teases this in the final pages.

You can start reading The Bridge right now on Leonard’s website. He has the entire book online for free for a few more weeks. If you’ve missed the free period, the Kindle edition is currently $2.99.

A Neural Network Can Now Be Your Writing Assistant

July 14, 2017 by Cameron Coward 15 Comments

Writing is a difficult job; though, as a primarily word-based site, we may be a little biased here at Hackaday. Not only does a writer have to know the basics, like what a semicolon is and when to use one, they also need to build sentences that convey information in a manner that is pleasant to read. As many commenters like to point out, even we struggle with this on occasion (lauded and scholarly as we are).

Wouldn’t it be better if we could let our computers do the heavy lifting for us? After all, a monkey with infinite time will eventually write Shakespeare and all that. Surely, a computer can be programmed to do all that fancy word assembly while we sit back and enjoy some coffee. Well, that’s what [Robin Sloan] set out to do with a recurrent neural network-powered writing assistant.

Alright, so it doesn’t actually write completely on its own. Instead, [Robin’s] software takes advantage of [JC Johnson’s] torch-rnn project, and integrates it into Atom to autocomplete sentences. [Robin] trained his neural network on hundreds of old issues of the sci-fi magazines Galaxy and IF Magazine, which are available at the Internet Archive. Once the server and corresponding Atom package are installed, a writer can simply push the Tab key and the sentence will be completed.

The results are interesting. [Robin] himself says “it’s like writing with a deranged but very well-read parrot on your shoulder.” While it’s not likely to be used as a serious writing tool anytime soon, the potential is certainly intriguing. When trained on relevant source material, the integration into software like Atom could be very useful. If a neural network can compose music, surely it can write some silly tech articles.

[thanks to Tim Trzepacz for the tip!]

Typewriter image: LjL (Public domain).

World’s Worst Bitcoin Mining Rig

July 14, 2017 by Dan Maloney 26 Comments

Even if we don’t quite understand what’s happening in a Bitcoin mine, we all pretty much know what’s needed to set one up. Racks of GPUs and specialized software will eventually find a few of these vanishingly rare virtual treasures, but if you have enough time, even a Xerox Alto from 1973 can be turned into a Bitcoin mine. As for how much time it’ll take [Ken Shirriff]’s rig to find a Bitcoin, let’s just say that his Alto would need to survive the heat death of the universe. About 5000 times. And it would take the electricity generated by a small country to do it.

Even though it’s not exactly a profit center, it gives [Ken] a chance to show off his lovingly restored Alto. The Xerox machine is the granddaddy of all modern PCs, having introduced almost every aspect of the GUI world we live in. But with a processor built from discrete TTL chips and an instruction set that doesn’t even have logical OR or XOR functions, the machine isn’t exactly optimized for SHA-256 hashing. The fact that [Ken] was able to implement a mining algorithm at all is impressive, and his explanation of how Bitcoin mining is done is quite clear and a great primer for cryptocurrency newbies.

[Ken] seems to enjoy sending old computer hardware to the Bitcoin mines — he made an old IBM mainframe perform the trick a while back. But if you don’t have a room-size computer around, perhaps reading up on alternate uses for the block chain would be a good idea.

[via Dangerous Prototypes]

Sneak Thieves Beware: A Pi Watcheth

July 13, 2017 by James Hobson 8 Comments

Ever have that strange feeling that somebody is breaking into your workshop? Well, Hackaday.io user [Kenny] has whipped up a tutorial on how to scratch that itch by turning a spare Raspberry Pi you may have kicking around into a security camera system that notifies you at a moment’s notice.

The system works like this: a Raspberry Pi 3 and connected camera module remain vigilant, constantly scanning for motion and recording video. If motion is detected, it immediately snaps and sends a picture to the user’s mobile via PushBullet, then begins recording video. If there is still movement after a few seconds, the process repeats until the area is once again devoid of motion. This also permits a two-way communication with your Pi security system, so you can check in on the live feed whenever you feel the urge.

To get this working for you — assuming that your Pi has been recently updated — setup requires setting up a PushBullet account as well as installing it on your mobile and linking it with an API. For your Pi, you can go ahead with setting up some Python PushBullet libraries, installing FFmpeg, Pi Camera Notifier, and others. Or, install the ready-to-go image [Kenny] has prepared. He gets into the nitty-gritty of the code in his guide, so check that out or watch the tutorial video after the break.

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Improving The Accuracy Of Gas Sensors

July 13, 2017 by Brian Benchoff 12 Comments

If you need a sensor to detect gasses of some sort, you’ll probably be looking at the MQ series of gas sensors. These small metal cylinders contain a heater and some electrochemical sensor. Wire the heater up to a voltage, and connect one end of the resistor to an ADC, and you have a sensor for alcohol vapors, hydrogen sulfide, carbon monoxide, or ozone, depending on which model of sensor you’ve picked up.

These are simple analog devices, and as you would expect they’re sensitive to both temperature and humidity. [Davide Gironi] wanted a more accurate gas sensor, so he’s diving into a bit of overengineering and correlating the output of these sensors against temperature and humidity.

There’s a difference between accuracy and precision, and if you want to calibrate gas sensors, you’ll need to calibrate them against something. Instead of digging out a gas sensor of known precision, [Davide] took the easy way out: he graphed the curves on the datasheets for these sensors. It’s brilliant in its simplicity.

These numbers were thrown into R, and with a bit of work, [Davide] had a look up table of various concentrations of gasses plotted against certain resistances. In testing these sensors, he found a higher correlation between humidity and temperature and gas concentrations, which one would expect.

The files for these sensors are available on [Davide]’s website, and he included a neat little video showing everyone what went into these calculations. You can check that out below.

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