Turntable photography has seen a rise in popularity driven by online shopping. If you can’t hold it in your hand at least you can see what it looks like from all angles. From the still image, [Petteri Aimonen’s] roll-your-own turntable looks great. It’s completely enclosed and has a very nice paint job. But when you see it in action it appears to suffer from a stutter.
A few folks over at Carnegie Mellon have come up with a very simple way to do high-speed motion tracking (PDF) with little more than a flashlight. It’s called Lumitrack, and while it looks like a Wiimote on the surface, it is in reality much more accurate and precise.
The system works by projecting structured light onto two linear optical sensors. The pattern of the light is an m-sequence – basically a barcode where every subset of the m-sequence is unique. By shining this light onto a linear sensor, Lumitrack can calculate where the light is coming from, and thus the position of whatever is holding the light.
Even though the entire system consists of only an ARM microcontroller (in the form of a Maple Mini board), two linear optical sensors, and a flashlight with an m-sequence gel, it’s very accurate and very, very fast. The team is able to read the position at over 1000 frames/second, nearly the limit of what can be done with the Maple’s serial connection.
Already there are some interesting applications for this system – game controllers, including swords, flight yokes, and toy cars, and also more artistic endeavors such as a virtual can of spray paint. It’s an interesting piece of tech, and with the right parts, something any of us can build at home.
You can see the Lumitrack demo video below.
[Darkmoonsinger’s] sister is finishing her graduate degree in mathematics, and [Darkmoonsinger] wanted to give her a gift that fit with her achievement. Naturally, building a Sieve of Eratosthenes using an LED matrix and an Arduino made perfect sense. If you’re unfamiliar, a Sieve of Eratosthenes is a simple, but very efficient, technique for finding prime numbers. Starting with a group of numbers, you step through each one in order. If it’s prime, you eliminate any multiples from the list. After a few iterations, the numbers remaining are all primes. After getting the LED matrix and sieve algorithm running, [Darkmoonsinger] designed an enclosure for the project. She made a couple of mistakes with this part, and happily included them for everyone’s benefit.
It only figures primes up to 64, and she lights the LED for 1 because it ‘makes the array look prettier’. Also, we couldn’t help but think that mounting the components a bit differently would have made a cleaner install (here’s a prime number generator with a backlit faceplate). However, that probably doesn’t matter to his sister. As they say, it’s the thought that counts, and we never get tired of seeing people build rather than buy!
One of our tipsters led us onto a very cool project by a British university team — It’s called Eidos, and it’s a real-time audio and visual augmentation system.
The creators embarked on this design journey after wondering if there was a way they could control and tune their senses. Imagine Superman and his ability to pick out one voice out of thousand — with this technology, it could be possible.
The clunky white goggles shown in the image above is the concept behind the visual augmentation. It’s akin to long-exposure photography, except that it is in real-time and is fluid video. We’re not sure how this could help anyone, but we have to admit it would be pretty cool to play around with. Maybe if Google Glass ever came out someone could write an app for it to mimic this!
The second device can target your hearing to a specific person in a noisy environment, zoning out all the unnecessary distractions. This could be very helpful for people suffering from attention deficit disorders, although we must imagine it would be very strange to get used to. Can you imagine blocking out everything and only looking at a person’s face and listening to their voice?
Unfortunately there is not much information about the actual tech or software behind these devices or if they even in fact work, but the concept was so interesting we just had to share it. Stick around after the break to see a video explanation and demonstration of the proposed technology.
There’s been some good .STL manipulation tips in this week.
The first one is called stl_tools, and it’s a Python library to convert images or text to 3D-printable STL files. The examples shown are quite impressive, and it even does a top notch job of taking a 2D company logo into 3D! We can see this being quite handy if you need some quick 3D text, and either don’t use CAD, or really just need a one click solution. Now if only .STLs were easier to edit afterwards…
The second one is a Javascript based Leap Motion Controller STL manipulator, which lets you pick STLs and manipulate them individually with your fingers. If you happen to have a Leap, this could be a great way to show off 3D parts at a presentation or hackerspace talk, especially if you want to add a [Tony Stark] vibe to your presentation! Stick around after the break to see it in action — Now all we need are some good hologram generators…
Continue reading “STL Fun: Converting Images To STL Geometry”
[Phillip] wanted to play with the C preprocessor. He decided to do that by creating a 4 bit full adder. We know this is pretty useless in everyday life, but it was a great learning experience. The beauty of this adder is right at the start. [Phillip] defines truth tables for XOR and AND. He’s able to then create strings that reference these truth tables.
For example: the first line of [Phillip’s] AND table is #define AND_00 0. If the preprocessor concatenates strings that equal “AND_00” they will then be converted to 0. This is the groundwork for the half adder .
The next step is the operational logic, which of course falls upon macros:
/* Full adder macros */ /* Out = (A ^ B) ^ cin */ #define FULL_ADD_OUT( a, b, cin ) \ XOR( XOR( a, b ), cin ) /* Carry_out = (A & B) ^ (Carry_in & (A ^ B)) */ /* The standard adder uses OR for the last 'gate' - this can safely be changed to XOR, which has been done here to avoid defining an OR operator */ #define FULL_ADD_CARRY( a, b, cin ) \ XOR( AND( XOR( a, b ), cin ), AND( a, b ) )
Continue reading “Create A Full Adder Using The C Preprocessor”
[Kos] tipped us about an article he made presenting his experiences in designing and implementing a core rope memory. This magnetic read-only memory (ROM), contrary to ordinary coincident-current magnetic core memories (used for RAM), uses the ferrite cores as transformers. If you look at the picture above, you’ll count 7 of them. This sets the memory word size (7bits). A new word is added to the memory by passing (or not) a wire through the ferrite holes. If you then pass an alternating current through this wire, a current will be induced (or not) in the other wire turned 30 times around the ferrite (alias transformer secondary).
In [Kos]’s setup, an input pulse of 5V generates output pulses of 15V. For demonstration purposes, he “wrote” a simple program that lights up digits in a seven segment display. Therefore, different numbers will light up depending on which wire he uses to pass the AC current.
These days core memory hacks are few and far between. But looking at this one, and the one we saw in August, makes want more. If you know of any others don’t hesitate to send us a tip.
